/*****************************************************************************

 * opus.h : Opus demux helpers

 *****************************************************************************

 * Copyright (C) 2012 VLC authors and VideoLAN

 *

 * Authors: Timothy B. Terriberry <tterribe@xiph.org>

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation; either version 2.1 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.

 *****************************************************************************/

/* Returns Opus frame duration in samples */

static inline unsigned opus_frame_duration(unsigned char *data, long len)

{

    static const int silk_fs_div[4] = { 6000, 3000, 1500, 1000 };

    unsigned toc;

    unsigned nframes;

    unsigned frame_size;

    unsigned nsamples;

    unsigned i_rate;

    if( len < 1 )

        return 0;

    toc = data[0];

    switch( toc&3 )

    {

        case 0:

            nframes = 1;

            break;

        case 1:

        case 2:

            nframes = 2;

            break;

        default:

            if( len < 2 )

                return 0;

            nframes = data[1]&0x3F;

            break;

    }

    i_rate = 48000;

    if( toc&0x80 )

        frame_size = (i_rate << (toc >> 3 & 3)) / 400;

    else if( ( toc&0x60 ) == 0x60 )

        frame_size = i_rate/(100 >> (toc >> 3 & 1));

    else

        frame_size = i_rate*60 / silk_fs_div[toc >> 3 & 3];

    nsamples = nframes*frame_size;

    if( nsamples*25 > i_rate*3 )

        return 0;

    return nsamples;

}