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/*
* MPEG-4 Audio common code
* Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "bitstream.h"
#include "mpeg4audio.h"
const int ff_mpeg4audio_sample_rates[16] = {
96000, 88200, 64000, 48000, 44100, 32000,
24000, 22050, 16000, 12000, 11025, 8000, 7350
};
const uint8_t ff_mpeg4audio_channels[8] = {
0, 1, 2, 3, 4, 5, 6, 8
};
static inline int get_object_type(GetBitContext *gb)
{
int object_type = get_bits(gb, 5);
if (object_type == 31)
object_type = 32 + get_bits(gb, 6);
return object_type;
}
static inline int get_sample_rate(GetBitContext *gb, int *index)
{
*index = get_bits(gb, 4);
return *index == 0x0f ? get_bits(gb, 24) :
ff_mpeg4audio_sample_rates[*index];
}
int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
{
GetBitContext gb;
int specific_config_bitindex;
init_get_bits(&gb, buf, buf_size*8);
c->object_type = get_object_type(&gb);
c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
c->chan_config = get_bits(&gb, 4);
c->sbr = -1;
if (c->object_type == 5) {
c->ext_object_type = c->object_type;
c->sbr = 1;
c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
c->object_type = get_object_type(&gb);
} else
c->ext_object_type = 0;
specific_config_bitindex = get_bits_count(&gb);
if (c->ext_object_type != 5) {
int bits_left = buf_size*8 - specific_config_bitindex;
for (; bits_left > 15; bits_left--) {
if (show_bits(&gb, 11) == 0x2b7) { // sync extension
get_bits(&gb, 11);
c->ext_object_type = get_object_type(&gb);
if (c->ext_object_type == 5 && (c->sbr = get_bits1(&gb)) == 1)
c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
break;
} else
get_bits1(&gb); // skip 1 bit
}
}
return specific_config_bitindex;
}
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