[Matroska-devel] Specification Changes

Steve Lhomme slhomme at matroska.org
Sun Sep 23 11:39:46 CEST 2012

Hello everyone,

Following recent discussions we have introduce Matroska v4. It is
backward and forward compatible with previous versions.

New elements:
- CueDuration and CueRelativePosition so that matching subtitle blocks
can be retrieved easily when seeking

- TimecodeScaleDenominator which gives the Segment timecode in seconds
with the fraction TimecodeScale/TimecodeScaleDenominator. The value
1,000,000,000 ensures that the regular TimecodeScale values have the
same meaning as before.

Deprecated element:
- TrackTimecodeScale which was meant to combine tracks from different
timecode clocks (like PAL audio with NTSC video) but is bogus because
the Block timecodes have to be stored in sync with matching timecodes.
It shouldn't be up to the player to stretch audio or video time so
that they match. In the case of stretching audio that's quite tricky.

CueBlockNumber may be another candidate for deprecation now that we
have CueRelativePosition which is more convenient and faster. I'm not
sure it's used at all when writing or by any player.

Steve Lhomme
Matroska association Chairman

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