[Ffmpeg-devel] [PATCH] new version

[Andrew Voznytsa]

Michael Niedermayer wrote:
> Hi
>
> On Thu, Sep 14, 2006 at 06:59:31PM +0300, Andrew Voznytsa wrote:
>   
>> Michael Niedermayer wrote:
>>     
>>> wont that break amr stored in containers with a sample_rate different from
>>> that?
>>>   
>>>       
>> As it was mentioned by Benjamin Larsson it is invalid, but as you say -
>> possible.
>>
>> New, spears saving, patch attached. I'd notice that I need it in case
>> when lavc is used without lavf. Also, for illegal use fans, it would be
>> worth to change faad.c because sample_rate/channels are initialized
>> using GA_DecoderSpecificInfo() (AKA extradata) instead preserving
>> container values.
>>     
>
> i think channels can be set unconditionally and
> please avoid the code duplication
>
>   
If this is so principal: according to RFC 3267 'stereophonic speech
session' is possible. This RFC says that 'out-of-band signaling must be
used to indicate the number of channels' . And 'Although AMR and AMR-WB
codecs themselves do not support encoding of multi-channel audio content
into a single bit stream, they can be used to separately encode and
decode each of the individual channels'. IMO in such case number of AMR
frames feed to decoder (and decoded) is equal to signaled number of
channels. After decoding decoder should post process output data if
required (i.e. interleave samples). Currently lavc's wrapper does not
support this case. Then it would be right to check signaled number of
channels and if it is 2+ return error saying that multichannel decoding
not supported. Alternative way for decoding multichannel AMR would be to
use a few instances of lavc's AMR decoder wrapper, but for user side it
is a bit unusual use case when single track should be decoded using more
than one decoder. Plus it is better to implement it once on lavc side
(when required) then implementing it each time on user side.

--
Best regards,
Andrew Voznytsa

-------------- next part --------------
An embedded and charset-unspecified text was scrubbed...
Name: amr.patch
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20060914/5d921d58/attachment.txt>