[MPlayer-dev-eng] [PATCH] add support of compression algorithm 3 in mkv demuxer

[Ivan Kalvachev]

On 5/7/08, Alexander Beregalov <a.beregalov at gmail.com> wrote:
> Specs from http://www.matroska.org/technical/specs/ :
> ContentCompAlgo         The compression algorithm used. Algorithms that have
> been specified so far are: 0 - zlib, 1 - bzlib, 2 - lzo1x, 3 - Header
> Stripping.
> ContentCompSettings    Settings that might be needed by the
> decompressor. For Header Stripping (ContentCompAlgo=3), the bytes that
> were removed from the beggining of each frames of the track.
>
> I have such file, it works for me.
>
> | + A track
> |  + Track number: 2
> |  + Track UID: 2
> |  + Track type: audio
> |  + Lacing flag: 1
> |  + Default flag: 1
> |  + Codec ID: A_AC3
> |  + Content encodings
> |   + Content encoding
> |    + Content compression
> |     + Algorithm: 3 (header removal)
> |     + Settings: length 2, data: 0x0b 0x77
>
> See an attachment.
> Please comment.

After almost 4 years:
Patch committed (r34486).

There may be better ways to make this faster, but I guess that's how
it is done in the libavformat demuxer. Making it work for now is good
enough.

(And yes, a user having problem with osd text subtitles and
libavformat mkv demuxer,  provided me with sample that needs this
patch.).