modules/demux/opus.h

   1 /*****************************************************************************
   2  * opus.h : Opus demux helpers
   3  *****************************************************************************
   4  * Copyright (C) 2012 VLC authors and VideoLAN
   5  * $Id$
   6  *
   7  * Authors: Timothy B. Terriberry <tterribe@xiph.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify it
  10  * under the terms of the GNU Lesser General Public License as published by
  11  * the Free Software Foundation; either version 2.1 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public License
  20  * along with this program; if not, write to the Free Software Foundation,
  21  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  22  *****************************************************************************/
  23
  24 /* Returns Opus frame duration in samples */
  25
  26 static inline unsigned opus_frame_duration(unsigned char *data, long len)
  27 {
  28     static const int silk_fs_div[4] = { 6000, 3000, 1500, 1000 };
  29     unsigned toc;
  30     unsigned nframes;
  31     unsigned frame_size;
  32     unsigned nsamples;
  33     unsigned i_rate;
  34     if( len < 1 )
  35         return 0;
  36     toc = data[0];
  37     switch( toc&3 )
  38     {
  39         case 0:
  40             nframes = 1;
  41             break;
  42         case 1:
  43         case 2:
  44             nframes = 2;
  45             break;
  46         default:
  47             if( len < 2 )
  48                 return 0;
  49             nframes = data[1]&0x3F;
  50             break;
  51     }
  52     i_rate = 48000;
  53     if( toc&0x80 )
  54         frame_size = (i_rate << (toc >> 3 & 3)) / 400;
  55     else if( ( toc&0x60 ) == 0x60 )
  56         frame_size = i_rate/(100 >> (toc >> 3 & 1));
  57     else
  58         frame_size = i_rate*60 / silk_fs_div[toc >> 3 & 3];
  59     nsamples = nframes*frame_size;
  60     if( nsamples*25 > i_rate*3 )
  61         return 0;
  62     return nsamples;
  63 }