MKVToolnix is a set of tools to create, alter and inspect Matroska files under Windows.

With these tools one can get information about (mkvinfo) Matroska files, extract tracks/data from (mkvextract) Matroska files and create (mkvmerge) Matroska files from other media files. Matroska is a new multimedia file format aiming to become THE new container format for the future.

Changes in MKVToolnix 4.2.0 :

- mkvmerge: bug fix: mkvmerge was accessing invalid memory In certain cases, e.g. when appending Matroska files that use compression while turning compression off.
- mkvmerge: bug fix: Splitting output files by size was basing its decision when to create a new file on an uninitialized variable. This caused effects like a lot of small files being created with sizes much smaller than the intended split size.
- mkvmerge: bug fix: The speed with which mkvmerge skips garbage in DTS tracks has been greatly improved.
- mkvmerge: enhancement: Reading Matroska files: DisplayWidth & DisplayHeight values that are obviously not meant to represent pixels but only to be used for aspect ratio calculation (e.g. 16x9) are converted into proper ranges based on the track's PixelWidth & PixelHeight values and the quotient of DisplayWidth / DisplayHeight.
- mkvmerge: enhancement: Attachments will be rendered at the end of the file instead of at the beginning. The attachments will be placed after the cues but before the chapters. Fix for bug 516.
- mkvmerge: enhancement: Header removal compression has been enabled by default for MPEG-4 part 10 (AVC/h.264) video tracks with a NALU size field length of four bytes.
- mkvmerge: bug fix: Header removal compression has been deactivated for MPEG-4 part 2 (aka DivX/Xvid) video tracks due to incompatibility with packed bitstreams.
- mmg: enhancement: The taskbar progress is reset as soon as mkvmerge finishes/as soon as all jobs are done (Windows 7).
- mkvmerge: bug fix: Fixed reading AVC/h.264 tracks from AVI files if they're stored without NALUs inside the AVI. Was broken by a fix for handling AVC/h.264 in NALUs inside AVI.
- mkvmerge: bug fix: All readers that only handled file formats which do not contain more than one track did not respect the "--no-audio / --no-video / --no-subtitles" options. This applied to the following readers: AAC, AC3, AVC/h.264, CorePicture, Dirac, DTS, FLAC, IVF, MP3, MPEG ES, PGS/SUP, SRT, SSA, TrueHD, TTA, VC1, WAV and WavPack.
- mkvmerge: enhancement: Improved reading text files that use mixed end-of-line styles (DOS & Unix mixed).
- mkvmerge: bug fix: Fixed invalid memory access in the PCM packetizer. Fix for bug 510.
- mmg: bug fix: When mmg starts it will check the entries in the file and chapter menu's list of recently used files and remove those entries that no longer exist. Fix for bug 509.
- mkvmerge: bug fix: Fixed a crash when reading Matroska files that were damaged in a certain way.