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/*
* MPEG-4 Audio common code
* Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
* Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "get_bits.h"
#include "put_bits.h"
#include "mpeg4audio.h"
/**
* Parse MPEG-4 audio configuration for ALS object type.
* @param[in] gb bit reader context
* @param[in] c MPEG4AudioConfig structure to fill
* @return on success 0 is returned, otherwise a value < 0
*/
static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
{
if (get_bits_left(gb) < 112)
return AVERROR_INVALIDDATA;
if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
return AVERROR_INVALIDDATA;
// override AudioSpecificConfig channel configuration and sample rate
// which are buggy in old ALS conformance files
c->sample_rate = get_bits_long(gb, 32);
// skip number of samples
skip_bits_long(gb, 32);
// read number of channels
c->chan_config = 0;
c->channels = get_bits(gb, 16) + 1;
return 0;
}
const int avpriv_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 == AOT_ESCAPE)
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) :
avpriv_mpeg4audio_sample_rates[*index];
}
int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf,
int bit_size, int sync_extension)
{
GetBitContext gb;
int specific_config_bitindex, ret;
ret = init_get_bits(&gb, buf, bit_size);
if (ret < 0)
return ret;
c->object_type = get_object_type(&gb);
c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
c->chan_config = get_bits(&gb, 4);
if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
c->channels = ff_mpeg4audio_channels[c->chan_config];
c->sbr = -1;
c->ps = -1;
if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
// check for W6132 Annex YYYY draft MP3onMP4
!(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
if (c->object_type == AOT_PS)
c->ps = 1;
c->ext_object_type = AOT_SBR;
c->sbr = 1;
c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
c->object_type = get_object_type(&gb);
if (c->object_type == AOT_ER_BSAC)
c->ext_chan_config = get_bits(&gb, 4);
} else {
c->ext_object_type = AOT_NULL;
c->ext_sample_rate = 0;
}
specific_config_bitindex = get_bits_count(&gb);
if (c->object_type == AOT_ALS) {
skip_bits(&gb, 5);
if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
skip_bits_long(&gb, 24);
specific_config_bitindex = get_bits_count(&gb);
ret = parse_config_ALS(&gb, c);
if (ret < 0)
return ret;
}
if (c->ext_object_type != AOT_SBR && sync_extension) {
while (get_bits_left(&gb) > 15) {
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 == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
c->ps = get_bits1(&gb);
break;
} else
get_bits1(&gb); // skip 1 bit
}
}
//PS requires SBR
if (!c->sbr)
c->ps = 0;
//Limit implicit PS to the HE-AACv2 Profile
if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
c->ps = 0;
return specific_config_bitindex;
}
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