[FFmpeg-devel] Integrating the mod engine into FFmpeg - what is the best design approach?

Vladimir Pantelic vladoman
Fri Jul 16 17:01:06 CEST 2010


Vitor Sessak wrote:

> And your first idea did not have this problem. Since it is not a bad
> idea either, I'd like to explain it to see what the rest of the
> community think. In Sebastian's original approach, the demuxer would
> decode the file to a BSS an output it in an AVPacket. It would them
> define a CODEC_ID_SEQUENCER, and the decoder would be just a wrapper to
> libavsequencer to make the BSS ->  PCM conversion.

as a lavf/lavc user, I would expect the PCM to be the result of calling
the decoder, having to now call lavseq would be kinda new and disruptive.

for this approach how do we handle:

1) decode call cannot output ALL pcm at once, do we call it several times
without new input data to get all the PCM "decoded"?

2) how do we seek? since the BSS is one avpacket, how do timestamps work?

> The advantage of this approach is that the concept of demuxing/decoder
> does not make much sense for these formats, so this avoid the artificial
> distriction. Moreover, it makes a nice distinction of transcoding from
> one MOD format to other (with -acodec copy) to decoding it to PCM. The
> disadvantages is that API-wise it's less clear for external applications
> to get the BSS data (reading the AVPacket payload).

atm, no external apps exists that knows anything about BSS, so I don't see
any issue...





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