[Ffmpeg-devel] [PATCH] MS-GSM support: draft for review
Tue Nov 7 18:00:49 CET 2006
Benjamin Larsson wrote:
>>>> 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?
> "Microsoft's GSM 06.10 CODEC is not compatible with toast's frame format
> - they use 65-byte-frames (2 x 32 1/2) rather than rounding to 33, and
> they number the bits in their bytes from the other end. (Well done, guys.)"
Aargh, I knew that once, then Jutta Degener's group came out with
internal support for MS-GSM, you only had to remember you have to
advance sometimes by 32 sometimes by 33 bytes; the bit part of course I
> Doing a bitstream filter for that would mean writing a complete
> bitstream parser for the format.
What about considering this is a WAV-only thing and do everything in
wav_read/write_packet? Seeking, of course, would be a little more
acrobatic then with PCM.
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