/* * 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; }