mkvmerge -- Merge multimedia streams into a Matroska(tm) file

Table of contents

1. Synopsis

mkvmerge [global options] {-o out} [options1] {file1} [[options2] {file2}] [@optionsfile]

2. Description

This program takes the input from several media files and joins their streams (all of them or just a selection) into a Matroska(tm) file; see the Matroska website.

Important:

The order of command line options is important. Please read the section "Option order" if you're new to the program.

2.1. Global options

Option Description
-v, --verbose

Increase verbosity.

-q, --quiet

Suppress status output.

-o, --output file-name

Write to the file file-name. If splitting is used then this parameter is treated a bit differently. See the explanation for the --split option for details.

-w, --webm

Create a WebM compliant file. This is also turned on if the output file name's extension is "webm". This mode enforces several restrictions. The only allowed codecs are VP8 video and Vorbis audio tracks. Neither chapters nor tags are allowed. The DocType header item is changed to "webm".

--title title

Sets the general title for the output file, e.g. the movie name.

--default-language language-code

Sets the default language code that will be used for all tracks unless overwritten with the --language option. The default language code is 'und' for 'undefined'.

2.2. Segment info handling (global options)

Option Description
--segmentinfo filename.xml

Read segment information from a XML file. This file can contain the segment family UID, segment UID, previous and next segment UID elements. An example file and a DTD are included in the MKVToolNix distribution.

See the section about segment info XML files below for details.

--segment-uid SID1,SID2,...

Sets the segment UIDs to use. This is a comma-separated list of 128bit segment UIDs in the usual UID form: hex numbers with or without the "0x" prefix, with or without spaces, exactly 32 digits.

Each file created contains one segment, and each segment has one segment UID. If more segment UIDs are specified than segments are created then the surplus UIDs are ignored. If fewer UIDs are specified than segments are created then random UIDs will be created for them.

2.3. Chapter and tag handling (global options)

Option Description
--chapter-language language-code

Sets the ISO639-2 language code that is written for each chapter entry. Defaults to 'eng'. See the section about chapters below for details.

This option can be used both for simple chapter files and for source files that contain chapters but no information about the chapters' language, e.g. MP4 and OGM files.

--chapter-charset character-set

Sets the character set that is used for the conversion to UTF-8 for simple chapter files. See the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets.

This switch does also apply to chapters that are copied from certain container types, e.g. Ogg/OGM and MP4 files. See the section about chapters below for details.

--cue-chapter-name-format format

mkvmerge(1) supports reading CUE sheets for audio files as the input for chapters. CUE sheets usually contain the entries PERFORMER and TITLE for each index entry. mkvmerge(1) uses these two strings in order to construct the chapter name. With this option the format used for this name can be set.

If this option is not given then mkvmerge(1) defaults to the format '%p - %t' (the performer, followed by a space, a dash, another space and the title).

If the format is given then everything except the following meta characters is copied as-is, and the meta characters are replaced like this:

  • %p is replaced by the current entry's PERFORMER string,

  • %t is replaced by the current entry's TITLE string,

  • %n is replaced by the current track number and

  • %N is replaced by the current track number padded with a leading zero if it is < 10.

--chapters file-name

Read chapter information from the file file-name. See the section about chapters below for details.

--global-tags file-name

Read global tags from the file file-name. See the section about tags below for details.

2.4. General output control (advanced global options)

Option Description
--track-order FID1:TID1,FID2:TID2,...

This option changes the order in which the tracks for an input file are created. The argument is a comma separated list of pairs IDs. Each pair contains first the file ID (FID1) which is simply the number of the file on the command line starting at 0. The second is a track ID (TID1) from that file. If some track IDs are omitted then those tracks are created after the ones given with this option have been created.

--cluster-length spec

Limit the number of data blocks or the duration of data in each cluster. The spec parameter can either be a number n without a unit or a number d postfixed with 'ms'.

If no unit is used then mkvmerge(1) will put at most n data blocks into each cluster. The maximum number of blocks is 65535.

If the number d is postfixed with 'ms' then mkvmerge(1) puts at most d milliseconds of data into each cluster. The minimum for d is '100ms', and the maximum is '32000ms'.

mkvmerge(1) defaults to putting at most 65535 data blocks and 5000ms of data into a cluster.

Programs trying to find a certain frame can only seek directly to a cluster and have to read the whole cluster afterwards. Therefore creating larger clusters may lead to imprecise or slow seeking.

--no-cues

Tells mkvmerge(1) not to create and write the cue data which can be compared to an index in an AVI. Matroska(tm) files can be played back without the cue data, but seeking will probably be imprecise and slower. Use this only if you're really desperate for space or for testing purposes. See also option --cues which can be specified for each input file.

--clusters-in-meta-seek

Tells mkvmerge(1) to create a meta seek element at the end of the file containing all clusters. See also the section about the Matroska file layout.

--disable-lacing

Disables lacing for all tracks. This will increase the file's size, especially if there are many audio tracks. This option is not intended for everyday use.

--enable-durations

Write durations for all blocks. This will increase file size and does not offer any additional value for players at the moment.

--disable-track-statistics-tags

Normally mkvmerge(1) will write certain tags with statistics for each track. If such tags are already present then they will be overwritten. The tags are BPS, DURATION, NUMBER_OF_BYTES and NUMBER_OF_FRAMES.

Enabling this option prevents mkvmerge(1) from writing those tags and from touching any existing tags with same names.

--timecode-scale factor

Forces the timecode scale factor to factor. Valid values are in the range 1000..10000000 or the special value -1.

Normally mkvmerge(1) will use a value of 1000000 which means that timecodes and durations will have a precision of 1ms. For files that will not contain a video track but at least one audio track mkvmerge(1) will automatically chose a timecode scale factor so that all timecodes and durations have a precision of one audio sample. This causes bigger overhead but allows precise seeking and extraction.

If the special value -1 is used then mkvmerge(1) will use sample precision even if a video track is present.

2.5. File splitting, linking, appending and concatenation (more global options)

Option Description
--split specification

Splits the output file after a given size or a given time. Please note that tracks can only be split right before a key frame. Due to buffering mkvmerge(1) will split right before the next key frame after the split point has been reached. Therefore the split point may be a bit off from what the user has specified.

At the moment mkvmerge(1) supports four different modes.

  1. Splitting by size.

    Syntax: --split [size:]d[k|m|g]

    Examples: --split size:700m or --split 150000000

    The parameter d may end with 'k', 'm' or 'g' to indicate that the size is in KB, MB or GB respectively. Otherwise a size in bytes is assumed. After the current output file has reached this size limit a new one will be started.

    The 'size:' prefix may be omitted for compatibility reasons.

  2. Splitting after a duration.

    Syntax: --split [duration:]HH:MM:SS.nnnnnnnnn|ds

    Examples: --split duration:00:60:00.000 or --split 3600s

    The parameter must either have the form HH:MM:SS.nnnnnnnnn for specifying the duration in up to nano-second precision or be a number d followed by the letter 's' for the duration in seconds. HH is the number of hours, MM the number of minutes, SS the number of seconds and nnnnnnnnn the number of nanoseconds. Both the number of hours and the number of nanoseconds can be omitted. There can be up to nine digits after the decimal point. After the duration of the contents in the current output has reached this limit a new output file will be started.

    The 'duration:' prefix may be omitted for compatibility reasons.

  3. Splitting after specific timecodes.

    Syntax: --split timecodes:A[,B[,C...]]

    Example: --split timecodes:00:45:00.000,01:20:00.250,6300s

    The parameters A, B, C etc must all have the same format as the ones used for the duration (see above). The list of timecodes is separated by commas. After the input stream has reached the current split point's timecode a new file is created. Then the next split point given in this list is used.

    The 'timecodes:' prefix must not be omitted.

  4. Keeping specific parts by specifying timecode ranges while discarding others.

    Syntax: --split parts:start1-end1[,[+]start2-end2[,[+]start3-end3...]]

    Examples:

    1. --split parts:00:01:20-00:02:45,00:05:50-00:10:30

    2. --split parts:00:01:20-00:02:45,+00:05:50-00:10:30

    3. --split parts:-00:02:45,00:05:50-

    The parts mode tells mkvmerge(1) to keep certain ranges of timecodes while discarding others. The ranges to keep have to be listed after the parts: keyword and be separated by commas. A range itself consists of a start and an end timecode in the same format the other variations of --split accept (e.g. both 00:01:20 and 80s refer to the same timecode).

    If a start timecode is left out then it defaults to the previous range's end timecode. If there was no previous range then it defaults to the start of the file (see example 3).

    If an end timecode is left out then it defaults to the end of the source files which basically tells mkvmerge(1) to keep the rest (see example 3).

    Normally each range will be written to a new file. This can be changed so that consecutive ranges are written to the same file. For that the user has to prefix the start timecode with a +. This tells mkvmerge(1) not to create a new file and instead append the range to the same file the previous range was written to. Timecodes will be adjusted so that there will be no gap in the output file even if there was a gap in the two ranges in the input file.

    In example 1 mkvmerge(1) will create two files. The first will contain the content starting from 00:01:20 until 00:02:45. The second file will contain the content starting from 00:05:50 until 00:10:30.

    In example 2 mkvmerge(1) will create only one file. This file will contain both the content starting from 00:01:20 until 00:02:45 and the content starting from 00:05:50 until 00:10:30.

    In example 3 mkvmerge(1) will create two files. The first will contain the content from the start of the source files until 00:02:45. The second file will contain the content starting from 00:05:50 until the end of the source files.

    Note:

    Note that mkvmerge(1) only makes decisions about splitting at key frame positions. This applies to both the start and the end of each range. So even if an end timecode is between two key frames mkvmerge(1) will continue outputting the frames up to but excluding the following key frame.

  5. Keeping specific parts by specifying frame/field number ranges while discarding others.

    Syntax: --split parts-frames:start1-end1[,[+]start2-end2[,[+]start3-end3...]]

    Examples:

    1. --split parts-frames:137-258,548-1211

    2. --split parts-frames:733-912,+1592-2730

    3. --split parts-frames:-430,2512-

    The parts-frames mode tells mkvmerge(1) to keep certain ranges of frame/field numbers while discarding others. The ranges to keep have to be listed after the parts-frames: keyword and be separated by commas. A range itself consists of a start and an end frame/field number. Numbering starts at 1.

    If a start number is left out then it defaults to the previous range's end number. If there was no previous range then it defaults to the start of the file (see example 3).

    If an end number is left out then it defaults to the end of the source files which basically tells mkvmerge(1) to keep the rest (see example 3).

    Normally each range will be written to a new file. This can be changed so that consecutive ranges are written to the same file. For that the user has to prefix the start number with a +. This tells mkvmerge(1) not to create a new file and instead append the range to the same file the previous range was written to. Timecodes will be adjusted so that there will be no gap in the output file even if there was a gap in the two ranges in the input file.

    Note:

    Note that mkvmerge(1) only makes decisions about splitting at key frame positions. This applies to both the start and the end of each range. So even if an end frame/field number is between two key frames mkvmerge(1) will continue outputting the frames up to but excluding the following key frame.

    In example 1 mkvmerge(1) will create two files. The first will contain the content starting from the first key frame at or after 137 up to but excluding the first key frame at or after 258. The second file will contain the content starting from 548 until 1211.

    In example 2 mkvmerge(1) will create only one file. This file will contain both the content starting from 733 until 912 and the content starting from 1592 until 2730.

    In example 3 mkvmerge(1) will create two files. The first will contain the content from the start of the source files until 430. The second file will contain the content starting from 2512 until the end of the source files.

    This mode considers only the first video track that is output. If no video track is output no splitting will occur.

    Note:

    The numbers given with this argument are interpreted based on the number of Matroska(tm) blocks that are output. A single Matroska(tm) block contains either a full frame (for progressive content) or a single field (for interlaced content). mkvmerge does not distinguish between those two and simply counts the number of blocks. For example: If one wanted to split after the 25th full frame with interlaced content one would have to use 50 (two fields per full frame) as the split point.

  6. Splitting after specific frames/fields.

    Syntax: --split frames:A[,B[,C...]]

    Example: --split frames:120,237,891

    The parameters A, B, C etc must all be positive integers. Numbering starts at 1. The list of frame/field numbers is separated by commas. After the input stream has reached the current split point's frame/field number a new file is created. Then the next split point given in this list is used.

    The 'frames:' prefix must not be omitted.

    This mode considers only the first video track that is output. If no video track is output no splitting will occur.

    Note:

    The numbers given with this argument are interpreted based on the number of Matroska(tm) blocks that are output. A single Matroska(tm) block contains either a full frame (for progressive content) or a single field (for interlaced content). mkvmerge does not distinguish between those two and simply counts the number of blocks. For example: If one wanted to split after the 25th full frame with interlaced content one would have to use 50 (two fields per full frame) as the split point.

  7. Splitting before specific chapters.

    Syntax: --split chapters:all or --split chapters:A[,B[,C...]]

    Example: --split chapters:5,8

    The parameters A, B, C etc must all be positive integers. Numbering starts at 1. The list of chapter numbers is separated by commas. Splitting will occur right before the first key frame whose timecode is equal to or bigger than the start timecode for the chapters whose numbers are listed. A chapter starting at 0s is never considered for splitting and discarded silently.

    The keyword all can be used instead of listing all chapter numbers manually.

    The 'chapters:' prefix must not be omitted.

    Note:

    The Matroska(tm) file format supports arbitrary deeply nested chapter structures called 'edition entries' and 'chapter atoms'. However, this mode only considers the top-most level of chapters across all edition entries.

For this splitting mode the output filename is treated differently than for the normal operation. It may contain a printf like expression '%d' including an optional field width, e.g. '%02d'. If it does then the current file number will be formatted appropriately and inserted at that point in the filename. If there is no such pattern then a pattern of '-%03d' is assumed right before the file's extension: '-o output.mkv' would result in 'output-001.mkv' and so on. If there's no extension then '-%03d' will be appended to the name.

--link

Link files to one another when splitting the output file. See the section on file linking below for details.

--link-to-previous segment-UID

Links the first output file to the segment with the segment UID given by the segment-UID parameter. See the section on file linking below for details.

--link-to-next segment-UID

Links the last output file to the segment with the segment UID given by the segment-UID parameter. See the section on file linking below for details.

--append-mode mode

Determines how timecodes are calculated when appending files. The parameter mode can have two values: 'file' which is also the default and 'track'.

When mkvmerge appends a track (called 'track2_1' from now on) from a second file (called 'file2') to a track (called 'track1_1') from the first file (called 'file1') then it has to offset all timecodes for 'track2_1' by an amount. For 'file' mode this amount is the highest timecode encountered in 'file1' even if that timecode was from a different track than 'track1_1'. In track mode the offset is the highest timecode of 'track1_1'.

Unfortunately mkvmerge cannot detect which mode to use reliably. Therefore it defaults to 'file' mode. 'file' mode usually works better for files that have been created independently of each other; e.g. when appending AVI or MP4 files. 'track' mode may work better for sources that are essentially just parts of one big file, e.g. for VOB and EVO files.

Subtitle tracks are always treated as if 'file' mode were active even if 'track' mode actually is.

--append-to SFID1:STID1:DFID1:DTID1[,...]

This option controls to which track another track is appended. Each spec contains four IDs: a file ID, a track ID, a second file ID and a second track ID. The first pair, "source file ID" and "source track ID", identifies the track that is to be appended. The second pair, "destination file ID" and "destination track ID", identifies the track the first one is appended to.

If this option has been omitted then a standard mapping is used. This standard mapping appends each track from the current file to a track from the previous file with the same track ID. This allows for easy appending if a movie has been split into two parts and both file have the same number of tracks and track IDs with the command mkvmerge -o output.mkv part1.mkv +part2.mkv.

+

A single '+' causes the next file to be appended instead of added. The '+' can also be put in front of the next file name. Therefore the following two commands are equivalent:

$ mkvmerge -o full.mkv file1.mkv + file2.mkv
$ mkvmerge -o full.mkv file1.mkv +file2.mkv
=

Normally mkvmerge(1) looks for files in the same directory as an input file that have the same base name and only differ in their running number (e.g. 'VTS_01_1.VOB', 'VTS_01_2.VOB', 'VTS_01_3.VOB' etc) and treats all of those files as if they were concatenated into a single big file. This option, a single '=', causes mkvmerge not to look for those additional files.

The '=' can also be put in front of the next file name. Therefore the following two commands are equivalent:

$ mkvmerge -o full.mkv = file1.mkv
$ mkvmerge -o full.mkv =file1.mkv
( file1 file2 )

If multiple file names are contained in a pair of parenthesis then those files will be treated as if they were concatenated into a single big file consisting of the content of each of the files one after the other.

This can be used for e.g. VOB files coming from a DVD or MPEG transport streams. It cannot be used if each file contains its own set of headers which is usually the case with stand-alone files like AVI or MP4.

Putting a file name into parenthesis also prevents mkvmerge(1) from looking for additional files with the same base name as described in option =. Therefore these two command lines are equivalent:

$ mkvmerge -o out.mkv = file.mkv
$ mkvmerge -o out.mkv '(' file.mkv ')'

Several things should be noted:

  1. There must be spaces both after the opening and before the closing parenthesis.

  2. Every parameter between parenthesis is interpreted as a file name. Therefore all options applying to this logical file must be listed before the opening parenthesis.

  3. Some shells treat parenthesis as special characters. Hence you must escape or quote them as shown in the example above.

2.6. Attachment support (more global options)

Option Description
--attachment-description description

Plain text description of the following attachment. Applies to the next --attach-file or --attach-file-once option.

--attachment-mime-type MIME type

MIME type of the following attachment. Applies to the next --attach-file or --attach-file-once option. A list of officially recognized MIME types can be found e.g. at the IANA homepage. The MIME type is mandatory for an attachment.

--attachment-name name

Sets the name that will be stored in the output file for this attachment. If this option is not given then the name will be derived from the file name of the attachment as given with the --attach-file or the --attach-file-once option.

--attach-file file-name, --attach-file-once file-name

Creates a file attachment inside the Matroska(tm) file. The MIME type must have been set before this option can used. The difference between the two forms is that during splitting the files attached with --attach-file are attached to all output files while the ones attached with --attach-file-once are only attached to the first file created. If splitting is not used then both do the same.

mkvextract(1) can be used to extract attached files from a Matroska(tm) file.

2.7. Options that can be used for each input file

Option Description
-a, --audio-tracks [!]n,m,...

Copy the audio tracks n, m etc. The numbers are track IDs which can be obtained with the --identify switch. They're not simply the track numbers (see section track IDs). Default: copy all audio tracks.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

-d, --video-tracks [!]n,m,...

Copy the video tracks n, m etc. The numbers are track IDs which can be obtained with the --identify switch. They're not simply the track numbers (see section track IDs). Default: copy all video tracks.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

-s, --subtitle-tracks [!]n,m,...

Copy the subtitle tracks n, m etc. The numbers are track IDs which can be obtained with the --identify switch. They're not simply the track numbers (see section track IDs). Default: copy all subtitle tracks.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

-b, --button-tracks [!]n,m,...

Copy the button tracks n, m etc. The numbers are track IDs which can be obtained with the --identify switch. They're not simply the track numbers (see section track IDs). Default: copy all button tracks.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

--track-tags [!]n,m,...

Copy the tags for tracks n, m etc. The numbers are track IDs which can be obtained with the --identify switch (see section track IDs). They're not simply the track numbers. Default: copy tags for all tracks.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

-m, --attachments [!]n[:all|first],m[:all|first],...

Copy the attachments with the IDs n, m etc to all or only the first output file. Each ID can be followed by either ':all' (which is the default if neither is entered) or ':first'. If splitting is active then those attachments whose IDs are specified with ':all' are copied to all of the resulting output files while the others are only copied into the first output file. If splitting is not active then both variants have the same effect.

The default is to copy all attachments to all output files.

If the IDs are prefixed with ! then the meaning is reversed: copy everything but the IDs listed after the !.

-A, --no-audio

Don't copy any audio track from this file.

-D, --no-video

Don't copy any video track from this file.

-S, --no-subtitles

Don't copy any subtitle track from this file.

-B, --no-buttons

Don't copy any button track from this file.

-T, --no-track-tags

Don't copy any track specific tags from this file.

--no-chapters

Don't copy chapters from this file.

-M, --no-attachments

Don't copy attachments from this file.

--no-global-tags

Don't copy global tags from this file.

--chapter-charset character-set

Sets the charset that is used for the conversion to UTF-8 for chapter information contained in the source file. See the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets.

--chapter-language language-code

Sets the ISO639-2 language code that is written for each chapter entry. This option can be used for source files that contain chapters but no information about the chapters' languages, e.g. for MP4 and OGM files.

-y, --sync TID:d[,o[/p]]

Adjust the timecodes of the track with the id TID by d ms. The track IDs are the same as the ones given with --identify (see section track IDs).

o/p: adjust the timestamps by o/p to fix linear drifts. p defaults to 1 if omitted. Both o and p can be floating point numbers.

Defaults: no manual sync correction (which is the same as d = 0 and o/p = 1.0).

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

--cues TID:none|iframes|all

Controls for which tracks cue (index) entries are created for the given track (see section track IDs). 'none' inhibits the creation of cue entries. For 'iframes' only blocks with no backward or forward references ( = I frames in video tracks) are put into the cue sheet. 'all' causes mkvmerge(1) to create cue entries for all blocks which will make the file very big.

The default is 'iframes' for video tracks and 'none' for all others. See also option --no-cues which inhibits the creation of cue entries regardless of the --cues options used.

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

--default-track TID[:bool]

Sets the 'default' flag for the given track (see section track IDs) if the optional argument bool is not present. If the user does not explicitly select a track himself then the player should prefer the track that has his 'default' flag set. Only one track of each kind (audio, video, subtitles, buttons) can have his 'default' flag set. If the user wants no track to have the default track flag set then he has to set bool to 0 for all tracks.

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

--forced-track TID[:bool]

Sets the 'forced' flag for the given track (see section track IDs) if the optional argument bool is not present. A player must play all tracks for which this flag is set to 1.

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

--blockadd TID:level

Keep only the BlockAdditions up to the level level for the given track. The default is to keep all levels. This option only affects certain kinds of codecs like WAVPACK4.

--track-name TID:name

Sets the track name for the given track (see section track IDs) to name.

--language TID:language

Sets the language for the given track (see section track IDs). Both ISO639-2 language codes and ISO639-1 country codes are allowed. The country codes will be converted to language codes automatically. All languages including their ISO639-2 codes can be listed with the --list-languages option.

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

-t, --tags TID:file-name

Read tags for the track with the number TID from the file file-name. See the section about tags below for details.

--aac-is-sbr TID[:0|1]

Tells mkvmerge(1) that the track with the ID TID is SBR AAC (also known as HE-AAC or AAC+). This options is needed if a) the source file is an AAC file (not for a Matroska(tm) file) and b) the AAC file contains SBR AAC data. The reason for this switch is that it is technically impossible to automatically tell normal AAC data from SBR AAC data without decoding a complete AAC frame. As there are several patent issues with AAC decoders mkvmerge(1) will never contain this decoding stage. So for SBR AAC files this switch is mandatory. The resulting file might not play back correctly or even not at all if the switch was omitted.

If the source file is a Matroska(tm) file then the CodecID should be enough to detect SBR AAC. However, if the CodecID is wrong then this switch can be used to correct that.

If mkvmerge wrongfully detects that an AAC file is SBR then you can add ':0' to the track ID.

--timecodes TID:file-name

Read the timecodes to be used for the specific track ID from file-name. These timecodes forcefully override the timecodes that mkvmerge(1) normally calculates. Read the section about external timecode files.

--default-duration TID:x

Forces the default duration of a given track to the specified value. Also modifies the track's timecodes to match the default duration. The argument x must be postfixed with 's', 'ms', 'us', 'ns', 'fps', 'p' or 'i' to specify the default duration in seconds, milliseconds, microseconds, nanoseconds, 'frames per second', 'progressive frames per second' or 'interlaced frames per second' respectively. The number x itself can be a floating point number or a fraction.

If the default duration is not forced then mkvmerge will try to derive the track's default duration from the container and/or the encoded bitstream for certain track types, e.g. AVC/h.264 or MPEG-2.

This option can also be used to change the FPS of video tracks without having to use an external timecode file.

--fix-bitstream-timing-information TID[:0|1]

Normally mkvmerge(1) does not change the timing information (frame/field rate) stored in the video bitstream. With this option that information is adjusted to match the container timing information. The container timing information can come from various sources: from the command line (see option --default-duration), the source container or derived from the bitstream.

Note:

This has only been implemented for AVC/h.264 video tracks so far.

--nalu-size-length TID:n

Forces the NALU size length to n bytes. This parameter is only used if the AVC/h.264 elementary stream packetizer is used. If left out it defaults to 4 bytes, but there are files that contain frames or slices that are all smaller than 65536 bytes. For such files you can use this parameter and decrease the size to 2.

--compression TID:n

Selects the compression method to be used for the track. Note that the player also has to support this method. Valid values are 'none', 'zlib', 'lzo'/'lxo1x', 'bz2'/'bzlib' and 'mpeg4_p2'/'mpeg4p2'. The values 'lzo'/'lxo1x' and 'bz2'/'bzlib' are only available if mkvmerge(1) has been compiled with support for the liblzo(tm) and bzlib(tm) compression libraries, respectively.

The compression method 'mpeg4_p2'/'mpeg4p2' is a special compression method called 'header removal' that is only available for MPEG4 part 2 video tracks.

The default for some subtitle tracks is 'zlib' compression. This compression method is also the one that most if not all playback applications support. Support for other compression methods other than 'none' is not assured.

2.8. Options that only apply to video tracks

Option Description
-f, --fourcc TID:FourCC

Forces the FourCC to the specified value. Works only for video tracks in the 'MS compatibility mode'.

--display-dimensions TID:widthxheight

Matroska(tm) files contain two values that set the display properties that a player should scale the image on playback to: display width and display height. These values can be set with this option, e.g. '1:640x480'.

Another way to specify the values is to use the --aspect-ratio or the --aspect-ratio-factor option (see below). These options are mutually exclusive.

--aspect-ratio TID:ratio|width/height

Matroska(tm) files contain two values that set the display properties that a player should scale the image on playback to: display width and display height. With this option mkvmerge(1) will automatically calculate the display width and display height based on the image's original width and height and the aspect ratio given with this option. The ratio can be given either as a floating point number ratio or as a fraction 'width/height', e.g. '16/9'.

Another way to specify the values is to use the --aspect-ratio-factor or --display-dimensions options (see above and below). These options are mutually exclusive.

--aspect-ratio-factor TID:factor|n/d

Another way to set the aspect ratio is to specify a factor. The original aspect ratio is first multiplied with this factor and used as the target aspect ratio afterwards.

Another way to specify the values is to use the --aspect-ratio or --display-dimensions options (see above). These options are mutually exclusive.

--cropping TID:left,top,right,bottom

Sets the pixel cropping parameters of a video track to the given values.

--stereo-mode TID:n|keyword

Sets the stereo mode for the video track with the track ID TID. The mode can either be a number n between 0 and 14 or one of these keywords:

'mono', 'side_by_side_left_first', 'top_bottom_right_first', 'top_bottom_left_first', 'checkerboard_right_first', 'checkerboard_left_first', 'row_interleaved_right_first', 'row_interleaved_left_first', 'column_interleaved_right_first', 'column_interleaved_left_first', 'anaglyph_cyan_red', 'side_by_side_right_first', 'anaglyph_green_magenta', 'both_eyes_laced_left_first', 'both_eyes_laced_right_first'.

2.9. Options that only apply to text subtitle tracks

Option Description
--sub-charset TID:character-set

Sets the character set for the conversion to UTF-8 for UTF-8 subtitles for the given track ID. If not specified the charset will be derived from the current locale settings. Note that a charset is not needed for subtitles read from Matroska(tm) files or from Kate streams, as these are always stored in UTF-8. See the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets.

This option can be used multiple times for an input file applying to several tracks by selecting different track IDs each time.

2.10. Other options

Option Description
-i, --identify file-name

Will let mkvmerge(1) probe the single file and report its type, the tracks contained in the file and their track IDs. If this option is used then the only other option allowed is the filename.

-I, --identify-verbose file-name

Will let mkvmerge(1) probe the single file and report its type, the tracks contained in the file and their track IDs. If this option is used then the only other option allowed is the filename.

This option causes mkvmerge(1) to output additional information about the container and each track within. The extra information is surronded by square brackets. It consists of space-saparated key/value pairs where keys and values are separated by a colon.

Each value is escaped according to the rules described in the section about escaping special characters in text.

-l, --list-types

Lists supported input file types.

--list-languages

Lists all languages and their ISO639-2 code which can be used with the --language option.

--priority priority

Sets the process priority that mkvmerge(1) runs with. Valid values are 'lowest', 'lower', 'normal', 'higher' and 'highest'. If nothing is given then 'normal' is used. On Unix like systems mkvmerge(1) will use the nice(2) function. Therefore only the super user can use 'higher' and 'highest'. On Windows all values are useable for every user.

Selecting 'lowest' also causes mkvmerge(1) to select idle I/O priority in addition to the lowest possible process priority.

--command-line-charset character-set

Sets the character set to convert strings given on the command line from. It defaults to the character set given by system's current locale. This settings applies to arguments of the following options: --title, --track-name and --attachment-description.

--output-charset character-set

Sets the character set to which strings are converted that are to be output. It defaults to the character set given by system's current locale.

-r, --redirect-output file-name

Writes all messages to the file file-name instead of to the console. While this can be done easily with output redirection there are cases in which this option is needed: when the terminal reinterprets the output before writing it to a file. The character set set with --output-charset is honored.

--ui-language code

Forces the translations for the language code to be used (e.g. 'de_DE' for the German translations). It is preferable to use the environment variables LANG, LC_MESSAGES and LC_ALL though. Entering 'list' as the code will cause mkvmerge(1) to output a list of available translations.

--debug topic

Turn on debugging for a specific feature. This option is only useful for developers.

--engage feature

Turn on experimental features. A list of available features can be requested with mkvmerge --engage list. These features are not meant to be used in normal situations.

--gui-mode

Turns on GUI mode. In this mode specially-formatted lines may be output that can tell a controlling GUI what's happening. These messages follow the format '#GUI#message'. The message may be followed by key/value pairs as in '#GUI#message#key1=value1#key2=value2…'. Neither the messages nor the keys are ever translated and always output in English.

@options-file

Reads additional command line arguments from the file options-file. See the section about option files for further information.

--capabilities

Lists information about optional features that have been compiled in and exit. The first line output will be the version information. All following lines contain exactly one word whose presence indicates that the feature has been compiled in. These features are:

  • 'BZ2' -- the bzlib(tm) compression library. Affects the available compression methods for the --compression option.

  • 'LZO' -- the lzo(tm) compression library. Affects the available compression methods for the --compression option.

  • 'FLAC' -- reading raw FLAC files and handling FLAC tracks in other containers, e.g. Ogg(tm) or Matroska(tm).

-h, --help

Show usage information and exit.

-V, --version

Show version information and exit.

--check-for-updates

Checks online for new releases by downloading the URL http://mkvtoolnix-releases.bunkus.org/latest-release.xml. Four lines will be output in key=value style: the URL from where the information was retrieved (key version_check_url), the currently running version (key running_version), the latest release's version (key available_version) and the download URL (key download_url).

Afterwards the program exists with an exit code of 0 if no newer release is available, with 1 if a newer release is available and with 2 if an error occured (e.g. if the update information could not be retrieved).

This option is only available if the program was built with support for libcurl.

3. Usage

For each file the user can select which tracks mkvmerge(1) should take. They are all put into the file specified with -o. A list of known (and supported) source formats can be obtained with the -l option.

Important:

The order of command line options is important. Please read the section "Option order" if you're new to the program.

4. Option order

The order in which options are entered is important for some options. Options fall into two categories:

  1. Options that affect the whole program and are not tied to any input file. These include but are not limited to --command-line-charset, --output or --title. These can appear anywhere on the command line.

  2. Options that affect a single input file or a single track in an input file. These options all apply to the following input file on the command line. All options applying to the same input (or to tracks from the same input file) file can be written in any order as long as they all appear before that input file's name. Examples for options applying to an input file are --no-chapters or --chapter-charset. Examples for options applying to a single track are --default-duration or --language.

The options are processed from left to right. If an option appears multiple times within the same scope then the last occurence will be used. Therefore the title will be set to "Something else" in the following example:

$ mkvmerge -o output.mkv --title 'This and that' input.avi --title 'Something else'

The following example shows that using the --language option twice is OK because they're used in different scopes. Even though they apply to the same track ID they apply to different input files and therefore have different scopes:

$ mkvmerge -o output.mkv --language 0:fre français.ogg --language 0:deu deutsch.ogg

5. Examples

Let's assume you have a file called MyMovie.avi and the audio track in a separate file, e.g. 'MyMovie.wav'. First you want to encode the audio to OggVorbis(tm):

$ oggenc -q4 -oMyMovie.ogg MyMovie.wav

After a couple of minutes you can join video and audio:

$ mkvmerge -o MyMovie-with-sound.mkv MyMovie.avi MyMovie.ogg

If your AVI already contains an audio track then it will be copied as well (if mkvmerge(1) supports the audio format). To avoid that simply do

$ mkvmerge -o MyMovie-with-sound.mkv -A MyMovie.avi MyMovie.ogg

After some minutes of consideration you rip another audio track, e.g. the director's comments or another language to 'MyMovie-add-audio.wav'. Encode it again and join it up with the other file:

$ oggenc -q4 -oMyMovie-add-audio.ogg MyMovie-add-audio.wav
$ mkvmerge -o MM-complete.mkv MyMovie-with-sound.mkv MyMovie-add-audio.ogg

The same result can be achieved with

$ mkvmerge -o MM-complete.mkv -A MyMovie.avi MyMovie.ogg MyMovie-add-audio.ogg

Now fire up mplayer(tm) and enjoy. If you have multiple audio tracks (or even video tracks) then you can tell mplayer(tm) which track to play with the '-vid' and '-aid' options. These are 0-based and do not distinguish between video and audio.

If you need an audio track synchronized you can do that easily. First find out which track ID the Vorbis track has with

$ mkvmerge --identify outofsync.ogg

Now you can use that ID in the following command line:

$ mkvmerge -o goodsync.mkv -A source.avi -y 12345:200 outofsync.ogg

This would add 200ms of silence at the beginning of the audio track with the ID 12345 taken from 'outofsync.ogg'.

Some movies start synced correctly but slowly drift out of sync. For these kind of movies you can specify a delay factor that is applied to all timestamps -- no data is added or removed. So if you make that factor too big or too small you'll get bad results. An example is that an episode I transcoded was 0.2 seconds out of sync at the end of the movie which was 77340 frames long. At 29.97fps 0.2 seconds correspond to approx. 6 frames. So I did

$ mkvmerge -o goodsync.mkv -y 23456:0,77346/77340 outofsync.mkv

The result was fine.

The sync options can also be used for subtitles in the same manner.

For text subtitles you can either use some Windows software (like SubRipper(tm)) or the subrip(tm) package found in transcode(1)'s sources in the 'contrib/subrip' directory. The general process is:

  1. extract a raw subtitle stream from the source:

    $ tccat -i /path/to/copied/dvd/ -T 1 -L | tcextract -x ps1 -t vob -a 0x20 | subtitle2pgm -o mymovie
  2. convert the resulting PGM images to text with gocr:

    $ pgm2txt mymovie
  3. spell-check the resulting text files:

    $ ispell -d american *txt
  4. convert the text files to a SRT file:

    $ srttool -s -w -i mymovie.srtx -o mymovie.srt

The resulting file can be used as another input file for mkvmerge(1):

$ mkvmerge -o mymovie.mkv mymovie.avi mymovie.srt

If you want to specify the language for a given track then this is easily done. First find out the ISO639-2 code for your language. mkvmerge(1) can list all of those codes for you:

$ mkvmerge --list-languages

Search the list for the languages you need. Let's assume you have put two audio tracks into a Matroska(tm) file and want to set their language codes and that their track IDs are 2 and 3. This can be done with

$ mkvmerge -o with-lang-codes.mkv --language 2:ger --language 3:dut without-lang-codes.mkv

As you can see you can use the --language switch multiple times.

Maybe you'd also like to have the player use the Dutch language as the default language. You also have extra subtitles, e.g. in English and French, and want to have the player display the French ones by default. This can be done with

$ mkvmerge -o with-lang-codes.mkv --language 2:ger --language 3:dut --default-track 3 without-lang-codes.mkv --language 0:eng english.srt --default-track 0 --language 0:fre french.srt

If you do not see the language or default track flags that you've specified in mkvinfo(1)'s output then please read the section about default values.

Turn off the compression for an input file.

$ mkvmerge -o no-compression.mkv --compression -1:none MyMovie.avi --compression -1:none mymovie.srt

6. Track IDs

Some of the options for mkvmerge(1) need a track ID to specify which track they should be applied to. Those track IDs are printed by the readers when demuxing the current input file, or if mkvmerge(1) is called with the --identify option. An example for such output:

$ mkvmerge -i v.mkv
File 'v.mkv': container: Matroska
Track ID 0: video (V_MS/VFW/FOURCC, DIV3)
Track ID 1: audio (A_MPEG/L3)

Do not confuse the track IDs that are assigned to the tracks that are placed in the output MKV file with the track IDs of the input files. Only the input file track IDs are used for options needing these values.

Also note that each input file has its own set of track IDs. Therefore the track IDs for file 'file1.ext' as reported by 'mkvmerge --identify' do not change no matter how many other input files are there or in which position 'file1.ext' is used.

Track IDs are assigned like this:

The special track ID '-1' is a wild card and applies the given switch to all tracks that are read from an input file.

The options that use the track IDs are the ones whose description contains 'TID'. The following options use track IDs as well: --audio-tracks, --video-tracks, --subtitle-tracks, --button-tracks and --track-tags.

7. Text files and character set conversions

Note:

This section applies to all programs in MKVToolNix even if it only mentions mkvmerge(1).

7.1. Introduction

All text in a Matroska(tm) file is encoded in UTF-8. This means that mkvmerge(1) has to convert every text file it reads as well as every text given on the command line from one character set into UTF-8. In return this also means that mkvmerge(1)'s output has to be converted back to that character set from UTF-8, e.g. if a non-English translation is used with --ui-language or for text originating from a Matroska(tm) file.

mkvmerge(1) does this conversion automatically based on the presence of a byte order marker (short: BOM) or the system's current locale. How the character set is inferred from the locale depends on the operating system that mkvmerge(1) is run on.

7.2. Byte order markers (BOM)

Text files that start with a BOM are already encoded in one representation of UTF. mkvmerge(1) supports the following five modes: UTF-8, UTF-16 Little and Big Endian, UTF-32 Little and Big Endian. Text files with a BOM are automatically converted to UTF-8. Any of the parameters that would otherwise set the character set for such a file (e.g. --sub-charset) is silently ignored.

7.3. Linux and Unix-like systems including Mac OS

On Unix-like systems mkvmerge(1) uses the setlocale(3) system call which in turn uses the environment variables LANG, LC_ALL and LC_CYPE. The resulting character set is often one of UTF-8 or the ISO-8859-* family and is used for all text file operations and for encoding strings on the command line and for output to the console.

7.4. Windows

On Windows the default character set used for converting text files is determined by a call to the GetACP() system call.

Reading the command line is done with the GetCommandLineW() function which already returns a Unicode string. Therefore the option --command-line-charset is ignored on Windows.

Output to the console consists of three scenarios:

  1. If the output is redirected with the option --redirect-output then the default charset is UTF-8. This can be changed with --output-charset.

    If the output is redirected with cmd.exe itself, e.g. with mkvinfo file.mkv > info.txt, then the charset is always UTF-8 and cannot be changed.

    Otherwise (when writing directly to the console) the Windows function WriteConsoleW() is used and the option --output-charset is ignored. The console should be able to output all Unicode characters for which the corresponding language support is installed (e.g. Chinese characters might not be displayed on English Windows versions).

7.5. Command line options

The following options exist that allow specifying the character sets:

8. Option files

An option file is a file mkvmerge(1) can read additional command line arguments from. This can be used in order to circumvent certain limitations of the shell or the operating system when executing external programs like a limited command line length.

There are several rules regarding option files. Lines whose first non-whitespace character is a hash mark ('#') are treated as comments and ignored. White spaces at the start and end of a line will be stripped. Each line must contain exactly one option.

A line not containing anything is also ignored. An empty argument is represented by the line '#EMPTY#'.

Several chars can be escaped, e.g. if you need to start a non-comment line with '#'. The rules are described in the section about escaping text.

Note that backslashes must always be escaped. Hash marks ('#') must be escaped if they should not start a comment.

The command line 'mkvmerge -o "my file.mkv" -A "a movie.avi" sound.ogg' could be converted into the following option file:

# Write to the file "c:\Matroska\my file.mkv" on Windows.
-o
c:\\Matroska\\my file.mkv
# Set the title to '#65'.
--title
\h65
# Only take the video from "a movie.avi".
-A
a movie.avi
sound.ogg

9. Escaping special chars in text

There are a few places in which special characters in text must or should be escaped. The rules for escaping are simple: each character that needs escaping is replaced with a backslash followed by another character.

The rules are: ' ' (a space) becomes '\s', '"' (double quotes) becomes '\2', ':' becomes '\c', '#' becomes '\h' and '\' (a single backslash) itself becomes '\\'.

10. Subtitles

There are several text and bitmap subtitle formats that can be embedded into Matroska(tm). Text subtitles must be recoded to UTF-8 so that they can be displayed correctly by a player (see the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets). Kate subtitles are already encoded in UTF-8 and do not have to be re-encoded.

The following subtitle formats are supported at the moment:

11. File linking

Matroska(tm) supports file linking which simply says that a specific file is the predecessor or successor of the current file. To be precise, it's not really the files that are linked but the Matroska(tm) segments. As most files will probably only contain one Matroska(tm) segment the following explanations use the term 'file linking' although 'segment linking' would be more appropriate.

Each segment is identified by a unique 128 bit wide segment UID. This UID is automatically generated by mkvmerge(1). The linking is done primarily via putting the segment UIDs (short: SID) of the previous/next file into the segment header information. mkvinfo(1) prints these SIDs if it finds them.

If a file is split into several smaller ones and linking is used then the timecodes will not start at 0 again but will continue where the last file has left off. This way the absolute time is kept even if the previous files are not available (e.g. when streaming). If no linking is used then the timecodes should start at 0 for each file. By default mkvmerge(1) does not use file linking. If you want that you can turn it on with the --link option. This option is only useful if splitting is activated as well.

Regardless of whether splitting is active or not the user can tell mkvmerge(1) to link the produced files to specific SIDs. This is achieved with the options --link-to-previous and --link-to-next. These options accept a segment SID in the format that mkvinfo(1) outputs: 16 hexadecimal numbers between 0x00 and 0xff prefixed with '0x' each, e.g. '0x41 0xda 0x73 0x66 0xd9 0xcf 0xb2 0x1e 0xae 0x78 0xeb 0xb4 0x5e 0xca 0xb3 0x93'. Alternatively a shorter form can be used: 16 hexadecimal numbers between 0x00 and 0xff without the '0x' prefixes and without the spaces, e.g. '41da7366d9cfb21eae78ebb45ecab393'.

If splitting is used then the first file is linked to the SID given with --link-to-previous and the last file is linked to the SID given with --link-to-next. If splitting is not used then the one output file will be linked to both of the two SIDs.

12. Default values

The Matroska(tm) specification states that some elements have a default value. Usually an element is not written to the file if its value is equal to its default value in order to save space. The elements that the user might miss in mkvinfo(1)'s output are the language and the default track flag elements. The default value for the language is English ('eng'), and the default value for the default track flag is true. Therefore if you used --language 0:eng for a track then it will not show up in mkvinfo(1)'s output.

13. Attachments

Maybe you also want to keep some photos along with your Matroska(tm) file, or you're using SSA subtitles and need a special TrueType(tm) font that's really rare. In these cases you can attach those files to the Matroska(tm) file. They will not be just appended to the file but embedded in it. A player can then show those files (the 'photos' case) or use them to render the subtitles (the 'TrueType(tm) fonts' case).

Here's an example how to attach a photo and a TrueType(tm) font to the output file:

$ mkvmerge -o output.mkv -A video.avi sound.ogg \
  --attachment-description "Me and the band behind the stage in a small get-together" \
  --attachment-mime-type image/jpeg \
  --attach-file me_and_the_band.jpg \
  --attachment-description "The real rare and unbelievably good looking font" \
  --attachment-type application/octet-stream \
  --attach-file really_cool_font.ttf

If a Matroska(tm) containing attachments file is used as an input file then mkvmerge(1) will copy the attachments into the new file. The selection which attachments are copied and which are not can be changed with the options --attachments and --no-attachments.

14. Chapters

The Matroska(tm) chapter system is more powerful than the old known system used by OGM files. The full specifications can be found at the Matroska website.

mkvmerge(1) supports two kinds of chapter files as its input. The first format, called 'simple chapter format', is the same format that the OGM tools expect. The second format is a XML based chapter format which supports all of Matroska(tm)'s chapter functionality.

14.1. The simple chapter format

This formmat consists of pairs of lines that start with 'CHAPTERxx=' and 'CHAPTERxxNAME=' respectively. The first one contains the start timecode while the second one contains the title. Here's an example:

CHAPTER01=00:00:00.000
CHAPTER01NAME=Intro
CHAPTER02=00:02:30.000
CHAPTER02NAME=Baby prepares to rock
CHAPTER03=00:02:42.300
CHAPTER03NAME=Baby rocks the house

mkvmerge(1) will transform every pair or lines into one Matroska(tm) ChapterAtom. It does not set any ChapterTrackNumber which means that the chapters all apply to all tracks in the file.

As this is a text file character set conversion may need to be done. See the section about text files and character sets for an explanation how mkvmerge(1) converts between character sets.

14.2. The XML based chapter format

The XML based chapter format looks like this example:

<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE Chapters SYSTEM "matroskachapters.dtd">
<Chapters>
  <EditionEntry>
    <ChapterAtom>
      <ChapterTimeStart>00:00:30.000</ChapterTimeStart>
      <ChapterTimeEnd>00:01:20.000</ChapterTimeEnd>
      <ChapterDisplay>
        <ChapterString>A short chapter</ChapterString>
        <ChapterLanguage>eng</ChapterLanguage>
      </ChapterDisplay>
      <ChapterAtom>
        <ChapterTimeStart>00:00:46.000</ChapterTimeStart>
        <ChapterTimeEnd>00:01:10.000</ChapterTimeEnd>
        <ChapterDisplay>
          <ChapterString>A part of that short chapter</ChapterString>
          <ChapterLanguage>eng</ChapterLanguage>
        </ChapterDisplay>
      </ChapterAtom>
    </ChapterAtom>
  </EditionEntry>
</Chapters>

With this format three things are possible that are not possible with the simple chapter format:

  1. The timestamp for the end of the chapter can be set,

  2. chapters can be nested,

  3. the language and country can be set.

The mkvtoolnix distribution contains some sample files in the doc subdirectory which can be used as a basis.

The following lists the supported XML tags, their data types and, where appropriate, the valid range for their values:

Chapters (master)
  EditionEntry (master)
    EditionUID (unsigned integer, valid range: 1 <= value)
    EditionFlagHidden (unsigned integer, valid range: 0 <= value <= 1)
    EditionFlagDefault (unsigned integer, valid range: 0 <= value <= 1)
    EditionFlagOrdered (unsigned integer, valid range: 0 <= value <= 1)
    ChapterAtom (master)
      ChapterAtom (master)
      ChapterUID (unsigned integer, valid range: 1 <= value)
      ChapterTimeStart (unsigned integer)
      ChapterTimeEnd (unsigned integer)
      ChapterFlagHidden (unsigned integer, valid range: 0 <= value <= 1)
      ChapterFlagEnabled (unsigned integer, valid range: 0 <= value <= 1)
      ChapterSegmentUID (binary, valid range: 1 <= length in bytes)
      ChapterSegmentEditionUID (unsigned integer, valid range: 1 <= value)
      ChapterPhysicalEquiv (unsigned integer)
      ChapterTrack (master)
        ChapterTrackNumber (unsigned integer, valid range: 1 <= value)
      ChapterDisplay (master)
        ChapterString (UTF-8 string)
        ChapterLanguage (UTF-8 string)
        ChapterCountry (UTF-8 string)
      ChapterProcess (master)
        ChapterProcessCodecID (unsigned integer)
        ChapterProcessPrivate (binary)
        ChapterProcessCommand (master)
          ChapterProcessTime (unsigned integer)
          ChapterProcessData (binary)

14.3. General notes

When splitting files mkvmerge(1) will correctly adjust the chapters as well. This means that each file only includes the chapter entries that apply to it, and that the timecodes will be offset to match the new timecodes of each output file.

mkvmerge(1) is able to copy chapters from Matroska(tm) source files unless this is explicitly disabled with the --no-chapters option. The chapters from all sources (Matroska(tm) files, Ogg files, MP4 files, chapter text files) are usually not merged but end up in separate ChapterEditions. Only if chapters are read from several Matroska(tm) or XML files that share the same edition UIDs will chapters be merged into a single ChapterEdition. If such a merge is desired in other situations as well then the user has to extract the chapters from all sources with mkvextract(1) first, merge the XML files manually and mux them afterwards.

15. Tags

15.1. Introduction

Matroska(tm) supports an extensive set of tags that is deprecated and a new, simpler system like it is is used in most other containers: KEY=VALUE. However, in Matroska(tm) these tags can also be nested, and both the KEY and the VALUE are elements of their own. The example file example-tags-2.xml shows how to use this new system.

15.2. Scope of the tags

Matroska(tm) tags do not automatically apply to the complete file. They can, but they also may apply to different parts of the file: to one or more tracks, to one or more chapters, or even to a combination of both. The the Matroska specification gives more details about this fact.

One important fact is that tags are linked to tracks or chapters with the Targets Matroska(tm) tag element, and that the UIDs used for this linking are not the track IDs mkvmerge(1) uses everywhere. Instead the numbers used are the UIDs which mkvmerge(1) calculates automatically (if the track is taken from a file format other than Matroska(tm)) or which are copied from the source file if the track's source file is a Matroska(tm) file. Therefore it is difficult to know which UIDs to use in the tag file before the file is handed over to mkvmerge(1).

mkvmerge(1) knows two options with which you can add tags to Matroska(tm) files: The --global-tags and the --tags options. The difference is that the former option, --global-tags, will make the tags apply to the complete file by removing any of those Targets elements mentioned above. The latter option, --tags, automatically inserts the UID that mkvmerge(1) generates for the tag specified with the TID part of the --tags option.

15.3. Example

Let's say that you want to add tags to a video track read from an AVI. mkvmerge --identify file.avi tells you that the video track's ID (do not mix this ID with the UID!) is 0. So you create your tag file, leave out all Targets elements and call mkvmerge(1):

$ mkvmerge -o file.mkv --tags 0:tags.xml file.avi

15.4. Tag file format

mkvmerge(1) supports a XML based tag file format. The format is very closely modeled after the Matroska specification. Both the binary and the source distributions of MKVToolNix come with a sample file called example-tags-2.xml which simply lists all known tags and which can be used as a basis for real life tag files.

The basics are:

15.5. Data types

The new Matroska(tm) tagging system only knows two data types, a UTF-8 string and a binary type. The first is used for the tag's name and the <String> element while the binary type is used for the <Binary> element.

As binary data itself would not fit into a XML file mkvmerge(1) supports two other methods of storing binary data. If the contents of a XML tag starts with '@' then the following text is treated as a file name. The corresponding file's content is copied into the Matroska(tm) element.

Otherwise the data is expected to be Base64 encoded. This is an encoding that transforms binary data into a limited set of ASCII characters and is used e.g. in email programs. mkvextract(1) will output Base64 encoded data for binary elements.

The deprecated tagging system knows some more data types which can be found in the official Matroska(tm) tag specs. As mkvmerge(1) does not support this system anymore these types aren't described here.

15.6. Known tags for the XML file format

The following lists the supported XML tags, their data types and, where appropriate, the valid range for their values:

Tags (master)
  Tag (master)
    Targets (master)
      TargetTypeValue (unsigned integer)
      TargetType (UTF-8 string)
      TrackUID (unsigned integer)
      EditionUID (unsigned integer)
      ChapterUID (unsigned integer)
      AttachmentUID (unsigned integer)
    Simple (master)
      Simple (master)
      Name (UTF-8 string)
      TagLanguage (UTF-8 string)
      DefaultLanguage (unsigned integer)
      String (UTF-8 string)
      Binary (binary)

16. The segment info XML files

With a segment info XML file it is possible to set certain values in the "segment information" header field of a Matroska(tm) file. All of these values cannot be set via other command line options.

Other "segment information" header fields can be set via command line options but not via the XML file. This includes e.g. the --title and the --timecode-scale options.

There are other elements that can be set neither via command line options nor via the XML files. These include the following elements: DateUTC (also known as the "muxing date"), MuxingApp, WritingApp and Duration. They're always set by mkvmerge(1) itself.

The following lists the supported XML tags, their data types and, where appropriate, the valid range for their values:

Info (master)
  SegmentUID (binary, valid range: length in bytes == 16)
  SegmentFilename (UTF-8 string)
  PreviousSegmentUID (binary, valid range: length in bytes == 16)
  PreviousSegmentFilename (UTF-8 string)
  NextSegmentUID (binary, valid range: length in bytes == 16)
  NextSegmentFilename (UTF-8 string)
  SegmentFamily (binary, valid range: length in bytes == 16)
  ChapterTranslate (master)
    ChapterTranslateEditionUID (unsigned integer)
    ChapterTranslateCodec (unsigned integer)
    ChapterTranslateID (binary)

17. Matroska file layout

The Matroska(tm) file layout is quite flexible. mkvmerge(1) will render a file in a predefined way. The resulting file looks like this:

[EBML head] [segment {meta seek #1} [segment information] [track information] {attachments} {chapters} [cluster 1] {cluster 2} ... {cluster n} {cues} {meta seek #2} {tags}]

The elements in curly braces are optional and depend on the contents and options used. A couple of notes:

The shortest possible Matroska(tm) file would look like this:

[EBML head] [segment [segment information] [track information] [cluster 1]]

This might be the case for audio-only files.

18. External timecode files

mkvmerge(1) allows the user to chose the timecodes for a specific track himself. This can be used in order to create files with variable frame rate video or include gaps in audio. A frame in this case is the unit that mkvmerge(1) creates separately per Matroska(tm) block. For video this is exactly one frame, for audio this is one packet of the specific audio type. E.g. for AC3 this would be a packet containing 1536 samples.

Timecode files that are used when tracks are appended to each other must only be specified for the first part in a chain of tracks. For example if you append two files, v1.avi and v2.avi, and want to use timecodes then your command line must look something like this:

$ mkvmerge ... --timecodes 0:my_timecodes.txt v1.avi +v2.avi

There are four formats that are recognized by mkvmerge(1). The first line always contains the version number. Empty lines, lines containing only whitespace and lines beginning with '#' are ignored.

18.1. Timecode file format v1

This format starts with the version line. The second line declares the default number of frames per second. All following lines contain three numbers separated by commas: the start frame (0 is the first frame), the end frame and the number of frames in this range. The FPS is a floating point number with the dot '.' as the decimal point. The ranges can contain gaps for which the default FPS is used. An example:

# timecode format v1
assume 27.930
800,1000,25
1500,1700,30

18.2. Timecode file format v2

In this format each line contains a timecode for the corresponding frame. This timecode must be given in millisecond precision. It can be a floating point number, but it doesn't have to be. You have to give at least as many timecode lines as there are frames in the track. The timecodes in this file must be sorted. Example for 25fps:

# timecode format v2
0
40
80

18.3. Timecode file format v3

In this format each line contains a duration in seconds followed by an optional number of frames per second. Both can be floating point numbers. If the number of frames per second is not present the default one is used. For audio you should let the codec calculate the frame timecodes itself. For that you should be using 0.0 as the number of frames per second. You can also create gaps in the stream by using the 'gap' keyword followed by the duration of the gap. Example for an audio file:

# timecode format v3
assume 0.0
25.325
7.530,38.236
gap, 10.050
2.000,38.236

18.4. Timecode file format v4

This format is identical to the v2 format. The only difference is that the timecodes do not have to be sorted. This format should almost never be used.

19. Exit codes

mkvmerge(1) exits with one of three exit codes:

20. Environment variables

mkvmerge(1) uses the default variables that determine the system's locale (e.g. LANG and the LC_* family). Additional variables:

Option Description
MKVTOOLNIX_DEBUG and its short form MTX_DEBUG

The content is treated as if it had been passed via the --debug option.

MKVTOOLNIX_ENGAGE and its short form MTX_ENGAGE

The content is treated as if it had been passed via the --engage option.

MKVTOOLNIX_OPTIONS and its short form MTX_OPTIONS

The content is split on white space. The resulting partial strings are treated as if it had been passed as command line options. If you need to pass special characters (e.g. spaces) then you have to escape them (see the section about escaping special characters in text).

21. See also

mkvinfo(1), mkvextract(1), mkvpropedit(1), mmg(1)

22. WWW

The latest version can always be found at the MKVToolNix homepage.