85 lines
2.8 KiB
C
85 lines
2.8 KiB
C
/*
|
|
* 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;
|
|
c->ext_sample_rate = 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;
|
|
}
|