[FFmpeg-soc] [QUESTION] Force more data to decode_frame()

[Michael Niedermayer]

On Sun, Jul 11, 2010 at 09:53:07PM +0300, Martin Storsjö wrote:
> On Sun, 11 Jul 2010, Mohamed Naufal wrote:
> 
> > On 11 July 2010 23:16, Mohamed Naufal <naufal11 at gmail.com> wrote:
> > > Hi
> > >
> > > Is there any way to force more data to be passed to decode_frame() of
> > > a decoder? G.723.1 has 4 frame types, each of size 24, 20, 10 and 1
> > > byte. For a particular frame of type 0, only 16B of data is being
> > > passed to decode_frame() when obviously 24B are needed. Is using a
> > > parser the only solution?
> > >
> > 
> > Also, the input is being read from a file. In the above case, EOF has
> > not been reached.
> 
> To add to the description of the issue, as I understood it from Mohamed on 
> irc, he's reading the data from a file, using the raw demuxer, and since 
> the frames have varying sizes, it may return an AVPacket containing an 
> incomplete frame at the end.
> 
> Generally, as far as I understand the issue, it can be solved in four 
> ways:
> - Implement a demuxer that doesn't return packets with incomplete frames, 
> thus more or less implementing a parser
> - Implement a proper parser and use it for properly splitting the packets 
> returned from the raw demuxer into individual frames
> - Make the decoder store the incomplete frame internally, return no 
> decoded data but no error code either, and prepend this data to the data 
> fed in the next decode call. This matches the way the mpegaudio decoder 
> worked earlier (more or less) - api-example.c relied on this behaviour 
> earlier, when it read 4 KB from the source file at a time and fed the 
> whole block to the decoder, which consumed all of it.
> - When the amount of raw data to decode drops below a certain threshold, 
> refill the buffer - in the same way as we do in api-example.c now. I'm not 
> sure how this design fits in ffmpeg.c, though.

Think about remuxing (-acodec copy) and what you would store for each of
the cases above in a container that does require a integral number of frames
at a time

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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