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FFmpeg/libavcodec/mpeg4audio.c
Andreas Rheinhardt 49bf94536f avcodec/mpeg4audio: Unavpriv and deduplicate mpeg4audio_sample_rates
avpriv_mpeg4audio_sample_rates has a size of 64B and it is currently
avpriv; a clone of it exists in aacenctab.h and from there it is inlined
in aacenc.c (which also uses the avpriv version) and in the FLV muxer.
This means that despite it being avpriv both libavformat as well as
libavcodec have copies already.

This situation is clearly suboptimal. Given the overhead of exporting
symbols (for x64 Elf/Linux/GNU: 2x2B version, 2x24B .dynsym, 24B .rela.dyn,
8B .got, 4B hash + twice the size of the name (here 31B)) the object is
unavprived, i.e. duplicated into libavformat when creating a shared
build; but the duplicates in the AAC encoder and FLV muxer are removed.

This involves splitting of the sample rate table into a file of its own;
this allowed to break some spurious dependencies (e.g. both the AAC
encoder as well as the Matroska demuxer actually don't need the
mpeg4audio_get_config stuff).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
2022-01-04 13:16:50 +01:00

180 lines
5.6 KiB
C

/*
* 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 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 "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, void *logctx)
{
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);
if (c->sample_rate <= 0) {
av_log(logctx, AV_LOG_ERROR, "Invalid sample rate %d\n", c->sample_rate);
return AVERROR_INVALIDDATA;
}
// 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 uint8_t ff_mpeg4audio_channels[14] = {
0,
1, // mono (1/0)
2, // stereo (2/0)
3, // 3/0
4, // 3/1
5, // 3/2
6, // 3/2.1
8, // 5/2.1
0,
0,
0,
7, // 3/3.1
8, // 3/2/2.1
24 // 3/3/3 - 5/2/3 - 3/0/0.2
};
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) :
ff_mpeg4audio_sample_rates[*index];
}
int ff_mpeg4audio_get_config_gb(MPEG4AudioConfig *c, GetBitContext *gb,
int sync_extension, void *logctx)
{
int specific_config_bitindex, ret;
int start_bit_index = get_bits_count(gb);
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];
else {
av_log(logctx, AV_LOG_ERROR, "Invalid chan_config %d\n", c->chan_config);
return AVERROR_INVALIDDATA;
}
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(gb, 24) != MKBETAG('\0','A','L','S'))
skip_bits(gb, 24);
specific_config_bitindex = get_bits_count(gb);
ret = parse_config_ALS(gb, c, logctx);
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 (c->ext_sample_rate == c->sample_rate)
c->sbr = -1;
}
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 - start_bit_index;
}
int avpriv_mpeg4audio_get_config2(MPEG4AudioConfig *c, const uint8_t *buf,
int size, int sync_extension, void *logctx)
{
GetBitContext gb;
int ret;
if (size <= 0)
return AVERROR_INVALIDDATA;
ret = init_get_bits8(&gb, buf, size);
if (ret < 0)
return ret;
return ff_mpeg4audio_get_config_gb(c, &gb, sync_extension, logctx);
}