libmpcodecs/ad_alaw.c

   1 /*
   2  * This file is part of MPlayer.
   3  *
   4  * MPlayer is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * MPlayer is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with MPlayer; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <unistd.h>
  22
  23 #include "config.h"
  24 #include "ad_internal.h"
  25
  26 static const ad_info_t info =
  27 {
  28         "aLaw/uLaw audio decoder",
  29         "alaw",
  30         "Nick Kurshev",
  31         "A'rpi",
  32         ""
  33 };
  34
  35 LIBAD_EXTERN(alaw)
  36
  37 #include "native/alaw.h"
  38
  39 static int init(sh_audio_t *sh_audio)
  40 {
  41   /* aLaw audio codec:*/
  42   if(!sh_audio->wf) return 0;
  43   sh_audio->channels=sh_audio->wf->nChannels;
  44   sh_audio->samplerate=sh_audio->wf->nSamplesPerSec;
  45   sh_audio->i_bps=sh_audio->channels*sh_audio->samplerate;
  46   sh_audio->samplesize=2;
  47   return 1;
  48 }
  49
  50 static int preinit(sh_audio_t *sh)
  51 {
  52   sh->audio_out_minsize=2048;
  53   sh->ds->ss_div = 1; // 1 samples/packet
  54   sh->ds->ss_mul = sh->wf->nChannels; // bytes/packet
  55   return 1;
  56 }
  57
  58 static void uninit(sh_audio_t *sh)
  59 {
  60 }
  61
  62 static int control(sh_audio_t *sh,int cmd,void* arg, ...)
  63 {
  64   int skip;
  65     switch(cmd)
  66     {
  67       case ADCTRL_SKIP_FRAME:
  68         skip=sh->i_bps/16;
  69         skip=skip&(~3);
  70         demux_read_data(sh->ds,NULL,skip);
  71         return CONTROL_TRUE;
  72       default:
  73         return CONTROL_UNKNOWN;
  74     }
  75   return CONTROL_UNKNOWN;
  76 }
  77
  78 static int decode_audio(sh_audio_t *sh_audio,unsigned char *buf,int minlen,int maxlen)
  79 {
  80  int len;
  81  int l=demux_read_data(sh_audio->ds,buf,minlen/2);
  82  unsigned short *d=(unsigned short *) buf;
  83  unsigned char *s=buf;
  84  len=2*l;
  85  if(sh_audio->format==6 || sh_audio->format==0x77616C61){
  86  /* aLaw */
  87    while(l>0){ --l; d[l]=alaw2short[s[l]]; }
  88  } else {
  89  /* uLaw */
  90     while(l>0){ --l; d[l]=ulaw2short[s[l]]; }
  91  }
  92  return len;
  93 }