Outputs 32-bit float instead of signed 16-bit int

[brandonkirsch]

This library uses libvorbis which only returns PCM data as 32-bit floats.

This unusual output format is unusable with several other utilities such as node-lame.

I think this library needs a routine similar to vorbisfile.c "ov_read_filter" that uses vorbis_ftoi() to correctly convert 32-bit floating points to the usual & expected signed 16-bit integers.

[mathom]

You can get by with something (probably slow, but fast enough for my uses) like this:

function float_to_int(options) {
    stream.Transform.call(this, options);
}
util.inherits(float_to_int, stream.Transform);

float_to_int.prototype._transform = function (chunk, enc, cb) {
    var b = new buffer.Buffer(chunk.length/4 * 2);
    for (var i=0, j=0; i<chunk.length; i+=4,j+=2) {
        var f = chunk.readFloatLE(i);
        f = f * 32768;
        if (f > 32767) f = 32767;
        if (f < -32768) f = -32768;

        b.writeInt16LE(Math.floor(f), j);
    }
    this.push(b);
    cb();
};

... SNIP ...

vorbisBuffer.pipe(new float_to_int()).pipe(audioSink);

[jobbautista9]

You could I think also use the tremor library made by Xiph.org for slower devices incapable of floating-point math (like older ARMs). It uses 16-bit signed samples:

long ov_read(OggVorbis_File *vf,char *buffer,int bytes_req,int *bitstream){
  int i,j;

  ogg_int32_t **pcm;
  long samples;

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

  while(1){
    if(vf->ready_state==INITSET){
      samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
      if(samples)break;
    }

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

  }

  if(samples>0){

    /* yay! proceed to pack data into the byte buffer */

    long channels=ov_info(vf,-1)->channels;

    if(samples>(bytes_req/(2*channels)))
      samples=bytes_req/(2*channels);

    for(i=0;i<channels;i++) { /* It's faster in this order */
      ogg_int32_t *src=pcm[i];
      short *dest=((short *)buffer)+i;
      for(j=0;j<samples;j++) {
        *dest=CLIP_TO_15(src[j]>>9);
        dest+=channels;
      }
    }

    vorbis_synthesis_read(&vf->vd,samples);
    vf->pcm_offset+=samples;
    if(bitstream)*bitstream=vf->current_link;
    return(samples*2*channels);
  }else{
    return(samples);
  }
}