[Ffmpeg-devel] [PATCH] MS-GSM support: draft for review

[Michel Bardiaux]

Michael Niedermayer wrote:
> Hi
> 
> On Tue, Nov 07, 2006 at 02:19:33PM +0100, Benjamin Larsson wrote:
>> Hi.
>>
>> Michael Niedermayer skrev:
>>> Hi
>>>
>> [...]
>>
>>
>>>  your implementation does not allow -acodec copy between msgsm<->gsm
>> There are other diffrences that won't allow this, just not the double 
>> packing of frames. For this to work the stream would need to pass a 
>> bitstream filter also. 
> 
> could you elaborate on the other things needed? i thought ms just
> packed 2frames together?

I thought the same.

> 
> 
>> And I think the time needed to write one could be 
>> better spent on something else that people actually use.
>>
>> And with regard of bitstream filters, I've heard lots of talk about it 
>> but no actual info on how to write one. Can you show some code/info 
>> about it?
> 
> see libavcodec/bitstream_filter.c
> 
> there are also some example filters in there
> 
Now I'm lost again.

1. Decoder: with a parser, or a bitstream filter?

2. Encoder: you said bitstream_filter, right? Problem is, it seems one 
has to call av_bitstream_filter_filter oneself before av_write_frame.

3. Both: since we go back to one codec, how are we going to tell the 
parser when it has to handle frames of 33, or 32 1/2? Maybe the right 
place to put this stuff is after all wav_read_packet. What do you think?

-- 
Michel Bardiaux
R&D Director
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