[Ffmpeg-devel] [PATCH] new version

[Andrew Voznytsa]

Michael Niedermayer wrote:
> Hi
>
> On Thu, Sep 14, 2006 at 10:25:31PM +0300, Andrew Voznytsa wrote:
>   
>> 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
>>
>>     
>
>   
>> Index: libavcodec/amr.c
>> ===================================================================
>> --- libavcodec/amr.c	(revision 6252)
>> +++ libavcodec/amr.c	(working copy)
>> @@ -107,6 +107,23 @@
>>      return(MR122);
>>  }
>>  
>> +static void amr_decode_fix_avctx(AVCodecContext * avctx)
>> +{
>> +    const int is_amr_wb = avctx->codec_id == CODEC_ID_AMR_WB;
>> +
>> +    if(avctx->sample_rate == 0)
>> +    {
>> +        avctx->sample_rate = 8000 * is_amr_wb;
>> +    }
>>     
>
> AMR_NB will end up with a sample_rate of 0 here ...
>
>
> [...]
>   
Sorry, missed. Will test it better next time.

Also - can you apply "[Ffmpeg-devel] [PATCH] avctx->frame_size for FAAD" ?

--
Best regards,
Andrew Voznytsa

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