[Live-devel] Problems with Streaming of AMR

[Martin]

Hi,

Ross Finlayson wrote:
>>So as you suggested I looked into the wis-streamer code as well and
>>included the part for the AMR-header:
>>
>>enum Mode ourAMRMode = MR122; // the only mode that we support
>>fLastFrameHeader = toc_byte[ourAMRMode];
>>fNumTruncatedBytes = 0;
>>
>>But on the receiver side the frame is still to short:
>>
>>[amr_nb @ 0xb45fc008]amr frame too short (31, should be 32)
>>
>>Maybe I'm still missing something?
> 
> 
> You're probably forgetting - in your encoder - to adjust the returned 
> frame size to allow for the extra 1-byte header.  Search for 
> "EncoderIncludeHeaderByte" in "AMREncoder/interf_enc.c" in the 
> "wis-streamer" code, to see where I had to modify the existing FFMPEG 
> code to do this.

thanks for uour help so far! I looked at the "wis-streamer" code but I
don't really understand what you changed:

Your code:

int EncoderIncludeHeaderByte = 1;
static int EncoderMMS( enum Mode mode, Word16 *param, UWord8 *stream, enum
      TXFrameType frame_type, enum Mode speech_mode )
{
   Word32 j = 0, k;
   Word16 *mask;
   int resultFrameSize = block_size[mode] - !EncoderIncludeHeaderByte;

   memset(stream, 0, resultFrameSize);

   if (EncoderIncludeHeaderByte) {
     *stream = toc_byte[mode];
     stream++;
   }

[...]

return resultFrameSize;

If I'm getting it right, the resultFrameSize is evaluated to
block_size[mode] (because !EncoderIncludeHeaderByte = 0).
So the code is the same as before:

static int EncoderMMS( enum Mode mode, Word16 *param, UWord8 *stream, enum
      TXFrameType frame_type, enum Mode speech_mode )
{
   memset(stream, 0, block_size[mode]);

   *stream = toc_byte[mode];
   stream++;

[...]

return block_size[mode];


It would be great if you could give me some further explanation.
Probably I don't see the obvious point...

Moreover, I want to leave the ffmpeg-code as is (if possible) and
include the header after the encoding step of ffmpeg:

avcodec_encode_audio(...,&buffer,...)

shift buffer 1 position to the right
buffer[0] = header.

Or do I completely misunderstand the "header-thing"?

Thanks in advance!

Martin