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ffmpeg / libavcodec / mpeg4audio.c @ 1e79771c

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/*
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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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    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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        c->ext_object_type = c->object_type;
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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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        int bits_left = buf_size*8 - get_bits_count(&gb);
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        for (; bits_left > 15; bits_left--) {
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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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                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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    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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}