modules/demux/opus.h

   1 /*****************************************************************************
   2  * opus.h : Opus demux helpers
   3  *****************************************************************************
   4  * Copyright (C) 2012 VLC authors and VideoLAN
   5  *
   6  * Authors: Timothy B. Terriberry <tterribe@xiph.org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 /* Returns Opus frame duration in samples */
  24
  25 static inline unsigned opus_frame_duration(unsigned char *data, long len)
  26 {
  27     static const int silk_fs_div[4] = { 6000, 3000, 1500, 1000 };
  28     unsigned toc;
  29     unsigned nframes;
  30     unsigned frame_size;
  31     unsigned nsamples;
  32     unsigned i_rate;
  33     if( len < 1 )
  34         return 0;
  35     toc = data[0];
  36     switch( toc&3 )
  37     {
  38         case 0:
  39             nframes = 1;
  40             break;
  41         case 1:
  42         case 2:
  43             nframes = 2;
  44             break;
  45         default:
  46             if( len < 2 )
  47                 return 0;
  48             nframes = data[1]&0x3F;
  49             break;
  50     }
  51     i_rate = 48000;
  52     if( toc&0x80 )
  53         frame_size = (i_rate << (toc >> 3 & 3)) / 400;
  54     else if( ( toc&0x60 ) == 0x60 )
  55         frame_size = i_rate/(100 >> (toc >> 3 & 1));
  56     else
  57         frame_size = i_rate*60 / silk_fs_div[toc >> 3 & 3];
  58     nsamples = nframes*frame_size;
  59     if( nsamples*25 > i_rate*3 )
  60         return 0;
  61     return nsamples;
  62 }