[FFmpeg-devel] Musepack SV8 Final

[Justin Ruggles]

Hi,

I saw a press release for Musepack SV8 Final on Hydrogenaudio.  It
mentions that SV8 audio could be supported in other containers such as
MKV and NUT, so that caught my attention.  After a quick look at the
source code, it appears that such support is not included as part of the
distribution.

So I looked at the state of our MPC8 support.  We have an SV8 format
demuxer and SV8 audio decoder, but we do not support de/muxing it in
other containers.

I asked some questions on HA regarding a few things and got a reply from
one of their developers.

Regarding extradata (specifically MKV CodecPrivate), they said that all
of the information in the SH packet except for the CRC is needed to
initialize the decoder (I assume they are referring to libmpcdec).  We
only use the last 2 bytes of the SH packet for extradata.  The Matroska
page says it's waiting on the spec to be finalized (which just happened
in the last few days) before stating the format for CodecPrivate.

Regarding packetization, the frame data within the AP packets should be
repacketized within the new container, which is compatible with the way
we handle it now.

As for identification, I got no reply about a wFormatTag, so I'm
guessing WAV/AVI is out of the question.  As for FOURCC, he/she
recommended MPCK, which is also the magic number for the SV8 container
format.

So adding support SV8 in NUT and MKV would be trivial. Should we take
the lead on the extradata/CodecPrivate matter or wait for an official
statement from Matroska?  Also, using a FOURCC for audio looks possible,
but there is a big FIXME above them currently... maybe those could be
split into a separate list and only used if a wFormatTag is not found
for containers that support it?

-Justin