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Topic: Tremor OggDec (Read 4391 times) previous topic - next topic
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Tremor OggDec

I've built an OggDec using Tremor, you can download it at:

http://sjeng.org/ftp/vorbis/oggdec.exe

May be faster than plain oggdec on systems like K6, Cyrix, 486, ...

I'm going to try a hybrid decoder and see if I can speed it up even more for Athlon, P3/P4.

Edit: naah, the hybrid decoder would be too hard

Tremor OggDec

Reply #1 –
I ran this on a 333MHz K6-2.

Code: [Select]
E:\>timer oggdec.exe jackal.ogg                                                            
                                                            
 OggDec v1.8 (libVorbis I 20020718) Compiled on: Aug 26 2002
 Encoder Version: 0                                         
 Serial Number: 21750                                       
                                                            
 Bitstream is 2 channel, 44100Hz                            
 Scale = 1.0000                                             
 Decoded length: 18056185 samples = 6:49 mins.              
 Encoded by: Xiphophorus libVorbis I 20011231               
 Decoding: jackal.ogg                      
                                                            
  100% decoded.                                             
                                                            
 ********** Done decoding all input files. **********       
Elapsed time is 110 seconds. (1 Min)



E:\>timer oggdec_tremor.exe jackal.ogg
OggDec 1.0 Tremor                                  
Decoding "jackal.ogg" to "jackal.wav"          
        [100.0%]                                   
Elapsed time is 68 seconds. (1 Min)


Impressive!
"Something bothering you, Mister Spock?"
 

Tremor OggDec

Reply #2 –
If anyone is interested, here is an addition to the Tremor lib that replaces ov_read_float with ov_read_int.
Code: [Select]
long ov_read_int(OggVorbis_File *vf,int ***pcm_channels,int length,
     int *bitstream){

  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){
         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=_process_packet(vf,1);
      if(ret==OV_EOF)return(0);
      if(ret<=0)return(ret);
    }
  }
}

The only thing to be aware of is that the returned integer values are scaled to 24 bits.