libmpcodecs/ad_alaw.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <unistd.h>
   4
   5 #include "config.h"
   6 #include "ad_internal.h"
   7
   8 static ad_info_t info =
   9 {
  10         "aLaw/uLaw audio decoder",
  11         "alaw",
  12         "Nick Kurshev",
  13         "A'rpi",
  14         ""
  15 };
  16
  17 LIBAD_EXTERN(alaw)
  18
  19 #include "alaw.h"
  20
  21 static int init(sh_audio_t *sh_audio)
  22 {
  23   /* aLaw audio codec:*/
  24   if(!sh_audio->wf) return 0;
  25   sh_audio->channels=sh_audio->wf->nChannels;
  26   sh_audio->samplerate=sh_audio->wf->nSamplesPerSec;
  27   sh_audio->i_bps=sh_audio->channels*sh_audio->samplerate;
  28   sh_audio->samplesize=2;
  29   return 1;
  30 }
  31
  32 static int preinit(sh_audio_t *sh)
  33 {
  34   sh->audio_out_minsize=2048;
  35   sh->ds->ss_div = 1; // 1 samples/packet
  36   sh->ds->ss_mul = sh->wf->nChannels; // bytes/packet
  37   return 1;
  38 }
  39
  40 static void uninit(sh_audio_t *sh)
  41 {
  42 }
  43
  44 static int control(sh_audio_t *sh,int cmd,void* arg, ...)
  45 {
  46   int skip;
  47     switch(cmd)
  48     {
  49       case ADCTRL_SKIP_FRAME:
  50         skip=sh->i_bps/16;
  51         skip=skip&(~3);
  52         demux_read_data(sh->ds,NULL,skip);
  53         return CONTROL_TRUE;
  54       default:
  55         return CONTROL_UNKNOWN;
  56     }
  57   return CONTROL_UNKNOWN;
  58 }
  59
  60 static int decode_audio(sh_audio_t *sh_audio,unsigned char *buf,int minlen,int maxlen)
  61 {
  62  int len;
  63  int l=demux_read_data(sh_audio->ds,buf,minlen/2);
  64  unsigned short *d=(unsigned short *) buf;
  65  unsigned char *s=buf;
  66  len=2*l;
  67  if(sh_audio->format==6 || sh_audio->format==0x77616C61){
  68  /* aLaw */
  69    while(l>0){ --l; d[l]=alaw2short[s[l]]; }
  70  } else {
  71  /* uLaw */
  72     while(l>0){ --l; d[l]=ulaw2short[s[l]]; }
  73  }
  74  return len;
  75 }