[vorbis] Output signal of the Tremor Codec

[John Edwards]

----- Original Message ----- 
m: "Ralph Giles" <giles at xiph.org>
To: <vorbis at xiph.org>
On Thursday, October 23, 2003 10:00 AM, Ralph Giles wrote:

Subject: Re: [vorbis] Output signal of the Tremor Codec

<p>> The lower-level vorbis_systhesis_pcmout() call returns a pointer to an
> array of channels, each an array of 32 bit integers with what looks like
> 24 bit precision. This may make more sense for your application,
> especially if you use a >16 bit DAC. In any case, it avoids a copy if
> there's room to do the interleaving in the FPGA. See the implementation
> of ov_read() in vorbisfile.c for an example of the conversion.

Actually, and for my own purposes, I added the following to vorbisfile.c in
the Tremor lib so that I could play with the decoded non-interleaved 16 bit
ints:

long ov_read_int(OggVorbis_File *vf,int ***pcm_channels,int length,
     int *bitstream){
  int i,j;

  if(vf->ready_state<OPENED)return(OV_EINVAL);

  while(1){
    if(vf->ready_state>=STREAMSET){
      int **pcm;
      long samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
      if(samples){
        long channels=ov_info(vf,-1)->channels;
        for(i=0;i<channels;i++) { /* It's faster in this order */
          for(j=0;j<samples;j++) {
            pcm[i][j]=CLIP_TO_15(pcm[i][j]>>9);
          }
        }
 if(pcm_channels)*pcm_channels=pcm;
 if(samples>length)samples=length;
 vorbis_synthesis_read(&vf->vd,samples);
 vf->pcm_offset+=samples;
 if(bitstream)*bitstream=vf->current_link;
 return samples;
      }
    }

    /* suck in another packet */
    {
      int ret=_fetch_and_process_packet(vf,1,1);
      if(ret==OV_EOF)return(0);
      if(ret<=0)return(ret);
    }

  }

}

John

<p>--- >8 ----
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