184 lines
6.0 KiB
C
184 lines
6.0 KiB
C
/*
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* MPEG-4 Audio common code
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* Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
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* Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "get_bits.h"
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#include "put_bits.h"
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#include "mpeg4audio.h"
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/**
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* Parse MPEG-4 audio configuration for ALS object type.
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* @param[in] gb bit reader context
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* @param[in] c MPEG4AudioConfig structure to fill
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* @return on success 0 is returned, otherwise a value < 0
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*/
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static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
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{
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if (get_bits_left(gb) < 112)
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return -1;
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if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
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return -1;
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// override AudioSpecificConfig channel configuration and sample rate
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// which are buggy in old ALS conformance files
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c->sample_rate = get_bits_long(gb, 32);
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// skip number of samples
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skip_bits_long(gb, 32);
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// read number of channels
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c->chan_config = 0;
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c->channels = get_bits(gb, 16) + 1;
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return 0;
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}
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const int ff_mpeg4audio_sample_rates[16] = {
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96000, 88200, 64000, 48000, 44100, 32000,
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24000, 22050, 16000, 12000, 11025, 8000, 7350
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};
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const uint8_t ff_mpeg4audio_channels[8] = {
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0, 1, 2, 3, 4, 5, 6, 8
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};
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static inline int get_object_type(GetBitContext *gb)
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{
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int object_type = get_bits(gb, 5);
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if (object_type == AOT_ESCAPE)
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object_type = 32 + get_bits(gb, 6);
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return object_type;
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}
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static inline int get_sample_rate(GetBitContext *gb, int *index)
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{
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*index = get_bits(gb, 4);
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return *index == 0x0f ? get_bits(gb, 24) :
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ff_mpeg4audio_sample_rates[*index];
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}
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int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_size)
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{
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GetBitContext gb;
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int specific_config_bitindex;
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init_get_bits(&gb, buf, buf_size*8);
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c->object_type = get_object_type(&gb);
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c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
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c->chan_config = get_bits(&gb, 4);
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if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
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c->channels = ff_mpeg4audio_channels[c->chan_config];
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c->sbr = -1;
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c->ps = -1;
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if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
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// check for W6132 Annex YYYY draft MP3onMP4
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!(show_bits(&gb, 3) & 0x03 && !(show_bits(&gb, 9) & 0x3F)))) {
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if (c->object_type == AOT_PS)
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c->ps = 1;
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c->ext_object_type = AOT_SBR;
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c->sbr = 1;
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c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
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c->object_type = get_object_type(&gb);
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if (c->object_type == AOT_ER_BSAC)
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c->ext_chan_config = get_bits(&gb, 4);
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} else {
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c->ext_object_type = AOT_NULL;
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c->ext_sample_rate = 0;
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}
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specific_config_bitindex = get_bits_count(&gb);
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if (c->object_type == AOT_ALS) {
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skip_bits(&gb, 5);
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if (show_bits_long(&gb, 24) != MKBETAG('\0','A','L','S'))
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skip_bits_long(&gb, 24);
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specific_config_bitindex = get_bits_count(&gb);
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if (parse_config_ALS(&gb, c))
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return -1;
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}
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if (c->ext_object_type != AOT_SBR) {
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while (get_bits_left(&gb) > 15) {
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if (show_bits(&gb, 11) == 0x2b7) { // sync extension
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get_bits(&gb, 11);
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c->ext_object_type = get_object_type(&gb);
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if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(&gb)) == 1)
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c->ext_sample_rate = get_sample_rate(&gb, &c->ext_sampling_index);
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if (get_bits_left(&gb) > 11 && get_bits(&gb, 11) == 0x548)
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c->ps = get_bits1(&gb);
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break;
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} else
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get_bits1(&gb); // skip 1 bit
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}
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}
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//PS requires SBR
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if (!c->sbr)
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c->ps = 0;
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//Limit implicit PS to the HE-AACv2 Profile
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if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
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c->ps = 0;
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return specific_config_bitindex;
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}
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static av_always_inline unsigned int copy_bits(PutBitContext *pb,
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GetBitContext *gb,
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int bits)
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{
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unsigned int el = get_bits(gb, bits);
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put_bits(pb, bits, el);
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return el;
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}
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int ff_copy_pce_data(PutBitContext *pb, GetBitContext *gb)
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{
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int five_bit_ch, four_bit_ch, comment_size, bits;
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int offset = put_bits_count(pb);
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copy_bits(pb, gb, 10); //Tag, Object Type, Frequency
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five_bit_ch = copy_bits(pb, gb, 4); //Front
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five_bit_ch += copy_bits(pb, gb, 4); //Side
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five_bit_ch += copy_bits(pb, gb, 4); //Back
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four_bit_ch = copy_bits(pb, gb, 2); //LFE
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four_bit_ch += copy_bits(pb, gb, 3); //Data
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five_bit_ch += copy_bits(pb, gb, 4); //Coupling
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if (copy_bits(pb, gb, 1)) //Mono Mixdown
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copy_bits(pb, gb, 4);
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if (copy_bits(pb, gb, 1)) //Stereo Mixdown
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copy_bits(pb, gb, 4);
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if (copy_bits(pb, gb, 1)) //Matrix Mixdown
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copy_bits(pb, gb, 3);
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for (bits = five_bit_ch*5+four_bit_ch*4; bits > 16; bits -= 16)
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copy_bits(pb, gb, 16);
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if (bits)
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copy_bits(pb, gb, bits);
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align_put_bits(pb);
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align_get_bits(gb);
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comment_size = copy_bits(pb, gb, 8);
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for (; comment_size > 0; comment_size--)
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copy_bits(pb, gb, 8);
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return put_bits_count(pb) - offset;
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}
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