[FFmpeg-devel] [PATCH] GSM-MS decoder and encoder

Michel Bardiaux mbardiaux
Mon Apr 28 17:25:55 CEST 2008

Diego Biurrun wrote:
> On Mon, Apr 28, 2008 at 01:53:56PM +0200, Michel Bardiaux wrote:
>> Diego Biurrun wrote:
>>> On Fri, Apr 25, 2008 at 12:10:06PM +0200, Michel Bardiaux wrote:
>>>> [...]
>>> While you guys are at it, there are still a couple of samples that do
>>> not work in ffplay:
>>> http://samples.mplayerhq.hu/A-codecs/GSM/sample-gsm-8000.gsm
>> This one cant be recognized:
>> [mp3 @ 0x843b514]Could not find codec parameters (Audio: mp2, 8 kb/s)
>> sample-gsm-8000.gsm: could not find codec parameters
>> What format is it?
> I would guess it is raw GSM.  You're the GSM expert, find out :)

Ah, but to-ast or not to-ast, that is the question (I *love* bad puns!)

TOAST being the file format that comes with the Berlin implementation 
known as libgsm. IIRC 4 'magic' bits are prepended (or is it appended?) 
to every block of 33 bytes minus 4 bits.

I really need to know the origin. Strangely 
http://samples.mplayerhq.hu/A-codecs/GSM/ states this file dates back to 
2002-Aug-08, I doubt that very much. Time for sherlocking my list 

>>> http://samples.mplayerhq.hu/A-codecs/GSM/sample-gsm-8000.mov
>> This one works for me:
>> ffmpeg -i sample-gsm-8000.mov -vn -acodec pcm_s16le sample-gsm-8000.mov.wav
>> produces a wav with correct sound.
> Hmm, disregard this, works fine now...

That is what you get for posting a problem without upgrading then 
posting your command line and messages :-)


Michel Bardiaux

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