/* * AC-3 parser * Copyright (c) 2003 Fabrice Bellard * Copyright (c) 2003 Michael Niedermayer * * 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 "config_components.h" #include "libavutil/channel_layout.h"#include "libavutil/mem.h"#include "parser.h"#include "ac3defs.h"#include "ac3tab.h"#include "ac3_parser.h"#include "ac3_parser_internal.h"#include "aac_ac3_parser.h"#include "get_bits.h" #define AC3_HEADER_SIZE 7 #if CONFIG_AC3_PARSER static const uint8_t eac3_blocks[4] = { 1, 2, 3, 6}; /** * Table for center mix levels * reference: Section 5.4.2.4 cmixlev */static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; /** * Table for surround mix levels * reference: Section 5.4.2.5 surmixlev */static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; int ff_ac3_find_syncword(const uint8_t *buf, int buf_size){ int i; for (i = 1; i < buf_size; i += 2) { if (buf[i] == 0x77 || buf[i] == 0x0B) { if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) { i--; break; } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) { break; } } } if (i >= buf_size) return AVERROR_INVALIDDATA; return i;} /** * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream. * GetBitContext within AC3DecodeContext must point to * the start of the synchronized AC-3 bitstream. */static int ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr){ /* read the rest of the bsi. read twice for dual mono mode. */ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { hdr->dialog_normalization[i] = -get_bits(gbc, 5); hdr->compression_exists[i] = get_bits1(gbc); if (hdr->compression_exists[i]) hdr->heavy_dynamic_range[i] = get_bits(gbc, 8); if (get_bits1(gbc)) skip_bits(gbc, 8); //skip language code if (get_bits1(gbc)) skip_bits(gbc, 7); //skip audio production information } skip_bits(gbc, 2); //skip copyright bit and original bitstream bit /* skip the timecodes or parse the Alternate Bit Stream Syntax */ if (hdr->bitstream_id != 6) { if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode1 if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode2 } else { if (get_bits1(gbc)) { hdr->preferred_downmix = get_bits(gbc, 2); hdr->center_mix_level_ltrt = get_bits(gbc, 3); hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); hdr->center_mix_level = get_bits(gbc, 3); hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); } if (get_bits1(gbc)) { hdr->dolby_surround_ex_mode = get_bits(gbc, 2); hdr->dolby_headphone_mode = get_bits(gbc, 2); skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1) } } /* skip additional bitstream info */ if (get_bits1(gbc)) { int i = get_bits(gbc, 6); do { skip_bits(gbc, 8); } while (i--); } return 0;} static int eac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr){ if (hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) return AC3_PARSE_ERROR_FRAME_TYPE; if (hdr->substreamid) return AC3_PARSE_ERROR_FRAME_TYPE; skip_bits(gbc, 5); // skip bitstream id /* volume control params */ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { hdr->dialog_normalization[i] = -get_bits(gbc, 5); hdr->compression_exists[i] = get_bits1(gbc); if (hdr->compression_exists[i]) hdr->heavy_dynamic_range[i] = get_bits(gbc, 8); } /* dependent stream channel map */ if (hdr->frame_type == EAC3_FRAME_TYPE_DEPENDENT) { hdr->channel_map_present = get_bits1(gbc); if (hdr->channel_map_present) { int64_t channel_layout = 0; int channel_map = get_bits(gbc, 16); for (int i = 0; i < 16; i++) if (channel_map & (1 << (EAC3_MAX_CHANNELS - i - 1))) channel_layout |= ff_eac3_custom_channel_map_locations[i][1]; if (av_popcount64(channel_layout) > EAC3_MAX_CHANNELS) { return AC3_PARSE_ERROR_CHANNEL_MAP; } hdr->channel_map = channel_map; } } /* mixing metadata */ if (get_bits1(gbc)) { /* center and surround mix levels */ if (hdr->channel_mode > AC3_CHMODE_STEREO) { hdr->preferred_downmix = get_bits(gbc, 2); if (hdr->channel_mode & 1) { /* if three front channels exist */ hdr->center_mix_level_ltrt = get_bits(gbc, 3); hdr->center_mix_level = get_bits(gbc, 3); } if (hdr->channel_mode & 4) { /* if a surround channel exists */ hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); } } /* lfe mix level */ if (hdr->lfe_on && (hdr->lfe_mix_level_exists = get_bits1(gbc))) { hdr->lfe_mix_level = get_bits(gbc, 5); } /* info for mixing with other streams and substreams */ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) { for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { // TODO: apply program scale factor if (get_bits1(gbc)) { skip_bits(gbc, 6); // skip program scale factor } } if (get_bits1(gbc)) { skip_bits(gbc, 6); // skip external program scale factor } /* skip mixing parameter data */ switch(get_bits(gbc, 2)) { case 1: skip_bits(gbc, 5); break; case 2: skip_bits(gbc, 12); break; case 3: { int mix_data_size = (get_bits(gbc, 5) + 2) << 3; skip_bits_long(gbc, mix_data_size); break; } } /* skip pan information for mono or dual mono source */ if (hdr->channel_mode < AC3_CHMODE_STEREO) { for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { if (get_bits1(gbc)) { /* note: this is not in the ATSC A/52B specification reference: ETSI TS 102 366 V1.1.1 section: E.1.3.1.25 */ skip_bits(gbc, 8); // skip pan mean direction index skip_bits(gbc, 6); // skip reserved paninfo bits } } } /* skip mixing configuration information */ if (get_bits1(gbc)) { for (int i = 0; i < hdr->num_blocks; i++) { if (hdr->num_blocks == 1 || get_bits1(gbc)) { skip_bits(gbc, 5); } } } } } /* informational metadata */ if (get_bits1(gbc)) { hdr->bitstream_mode = get_bits(gbc, 3); skip_bits(gbc, 2); // skip copyright bit and original bitstream bit if (hdr->channel_mode == AC3_CHMODE_STEREO) { hdr->dolby_surround_mode = get_bits(gbc, 2); hdr->dolby_headphone_mode = get_bits(gbc, 2); } if (hdr->channel_mode >= AC3_CHMODE_2F2R) { hdr->dolby_surround_ex_mode = get_bits(gbc, 2); } for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { if (get_bits1(gbc)) { skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type } } if (hdr->sr_code != EAC3_SR_CODE_REDUCED) { skip_bits1(gbc); // skip source sample rate code } } /* converter synchronization flag If frames are less than six blocks, this bit should be turned on once every 6 blocks to indicate the start of a frame set. reference: RFC 4598, Section 2.1.3 Frame Sets */ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && hdr->num_blocks != 6) { skip_bits1(gbc); // skip converter synchronization flag } /* original frame size code if this stream was converted from AC-3 */ if (hdr->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT && (hdr->num_blocks == 6 || get_bits1(gbc))) { skip_bits(gbc, 6); // skip frame size code } /* additional bitstream info */ if (get_bits1(gbc)) { int addbsil = get_bits(gbc, 6); for (int i = 0; i < addbsil + 1; i++) { if (i == 0) { /* In this 8 bit chunk, the LSB is equal to flag_ec3_extension_type_a which can be used to detect Atmos presence */ skip_bits(gbc, 7); hdr->eac3_extension_type_a = get_bits1(gbc); if (hdr->eac3_extension_type_a) { hdr->complexity_index_type_a = get_bits(gbc, 8); i++; } } else { skip_bits(gbc, 8); // skip additional bit stream info } } } return 0;} int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr){ int frame_size_code; memset(hdr, 0, sizeof(*hdr)); hdr->sync_word = get_bits(gbc, 16); if(hdr->sync_word != 0x0B77) return AC3_PARSE_ERROR_SYNC; /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */ hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F; if(hdr->bitstream_id > 16) return AC3_PARSE_ERROR_BSID; hdr->num_blocks = 6; hdr->ac3_bit_rate_code = -1; /* set default mix levels */ hdr->center_mix_level = 5; // -4.5dB hdr->surround_mix_level = 6; // -6.0dB /* set default dolby surround mode */ hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED; if(hdr->bitstream_id <= 10) { /* Normal AC-3 */ hdr->crc1 = get_bits(gbc, 16); hdr->sr_code = get_bits(gbc, 2); if(hdr->sr_code == 3) return AC3_PARSE_ERROR_SAMPLE_RATE; frame_size_code = get_bits(gbc, 6); if(frame_size_code > 37) return AC3_PARSE_ERROR_FRAME_SIZE; hdr->ac3_bit_rate_code = (frame_size_code >> 1); skip_bits(gbc, 5); // skip bsid, already got it hdr->bitstream_mode = get_bits(gbc, 3); hdr->channel_mode = get_bits(gbc, 3); if(hdr->channel_mode == AC3_CHMODE_STEREO) { hdr->dolby_surround_mode = get_bits(gbc, 2); } else { if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) hdr-> center_mix_level = center_levels[get_bits(gbc, 2)]; if(hdr->channel_mode & 4) hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)]; } hdr->lfe_on = get_bits1(gbc); hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8; hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift; hdr->bit_rate = (ff_ac3_bitrate_tab[hdr->ac3_bit_rate_code] * 1000) >> hdr->sr_shift; hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2; hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT; hdr->substreamid = 0; int ret = ac3_parse_header(gbc, hdr); if (ret < 0) return ret; } else { /* Enhanced AC-3 */ hdr->crc1 = 0; hdr->frame_type = get_bits(gbc, 2); if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) return AC3_PARSE_ERROR_FRAME_TYPE; hdr->substreamid = get_bits(gbc, 3); hdr->frame_size = (get_bits(gbc, 11) + 1) << 1; if(hdr->frame_size < AC3_HEADER_SIZE) return AC3_PARSE_ERROR_FRAME_SIZE; hdr->sr_code = get_bits(gbc, 2); if (hdr->sr_code == 3) { int sr_code2 = get_bits(gbc, 2); if(sr_code2 == 3) return AC3_PARSE_ERROR_SAMPLE_RATE; hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2; hdr->sr_shift = 1; } else { hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)]; hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code]; hdr->sr_shift = 0; } hdr->channel_mode = get_bits(gbc, 3); hdr->lfe_on = get_bits1(gbc); hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate / (hdr->num_blocks * 256); hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; int ret = eac3_parse_header(gbc, hdr); if (ret < 0) return ret; } hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode]; if (hdr->lfe_on) hdr->channel_layout |= AV_CH_LOW_FREQUENCY; return 0;} // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size){ GetBitContext gb; AC3HeaderInfo *hdr; int err; if (!*phdr) *phdr = av_mallocz(sizeof(AC3HeaderInfo)); if (!*phdr) return AVERROR(ENOMEM); hdr = *phdr; err = init_get_bits8(&gb, buf, size); if (err < 0) return AVERROR_INVALIDDATA; err = ff_ac3_parse_header(&gb, hdr); if (err < 0) return AVERROR_INVALIDDATA; return get_bits_count(&gb);} int av_ac3_parse_header(const uint8_t *buf, size_t size, uint8_t *bitstream_id, uint16_t *frame_size){ GetBitContext gb; AC3HeaderInfo hdr; uint8_t tmp[32 + AV_INPUT_BUFFER_PADDING_SIZE]; int err; size = FFMIN(32, size); memcpy(tmp, buf, size); memset(tmp + size, 0, AV_INPUT_BUFFER_PADDING_SIZE); err = init_get_bits8(&gb, tmp, size); if (err < 0) return AVERROR_INVALIDDATA; err = ff_ac3_parse_header(&gb, &hdr); if (err < 0) return AVERROR_INVALIDDATA; *bitstream_id = hdr.bitstream_id; *frame_size = hdr.frame_size; return 0;} static int ac3_sync(uint64_t state, int *need_next_header, int *new_frame_start){ int err; union { uint64_t u64; uint8_t u8[8 + AV_INPUT_BUFFER_PADDING_SIZE]; } tmp = { av_be2ne64(state) }; AC3HeaderInfo hdr; GetBitContext gbc; if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) { FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]); FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]); FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]); } init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54); err = ff_ac3_parse_header(&gbc, &hdr); if(err < 0) return 0; *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT); *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT); return hdr.frame_size;} static av_cold int ac3_parse_init(AVCodecParserContext *s1){ AACAC3ParseContext *s = s1->priv_data; s->header_size = AC3_HEADER_SIZE; s->crc_ctx = av_crc_get_table(AV_CRC_16_ANSI); s->sync = ac3_sync; return 0;} const AVCodecParser ff_ac3_parser = { .codec_ids = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 }, .priv_data_size = sizeof(AACAC3ParseContext), .parser_init = ac3_parse_init, .parser_parse = ff_aac_ac3_parse, .parser_close = ff_parse_close,}; #else int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size){ return AVERROR(ENOSYS);} int av_ac3_parse_header(const uint8_t *buf, size_t size, uint8_t *bitstream_id, uint16_t *frame_size){ return AVERROR(ENOSYS);}Lines 1–500 of 501. Load more
/* * AC-3 parser * Copyright (c) 2003 Fabrice Bellard * Copyright (c) 2003 Michael Niedermayer * * 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 "config_components.h" #include "libavutil/channel_layout.h" #include "libavutil/mem.h" #include "parser.h" #include "ac3defs.h" #include "ac3tab.h" #include "ac3_parser.h" #include "ac3_parser_internal.h" #include "aac_ac3_parser.h" #include "get_bits.h" #define AC3_HEADER_SIZE 7 #if CONFIG_AC3_PARSER static const uint8_t eac3_blocks[4] = { 1, 2, 3, 6 }; /** * Table for center mix levels * reference: Section 5.4.2.4 cmixlev */ static const uint8_t center_levels[4] = { 4, 5, 6, 5 }; /** * Table for surround mix levels * reference: Section 5.4.2.5 surmixlev */ static const uint8_t surround_levels[4] = { 4, 6, 7, 6 }; int ff_ac3_find_syncword(const uint8_t *buf, int buf_size) { int i; for (i = 1; i < buf_size; i += 2) { if (buf[i] == 0x77 || buf[i] == 0x0B) { if ((buf[i] ^ buf[i-1]) == (0x77 ^ 0x0B)) { i--; break; } else if ((buf[i] ^ buf[i+1]) == (0x77 ^ 0x0B)) { break; } } } if (i >= buf_size) return AVERROR_INVALIDDATA; return i; } /** * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream. * GetBitContext within AC3DecodeContext must point to * the start of the synchronized AC-3 bitstream. */ static int ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { /* read the rest of the bsi. read twice for dual mono mode. */ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { hdr->dialog_normalization[i] = -get_bits(gbc, 5); hdr->compression_exists[i] = get_bits1(gbc); if (hdr->compression_exists[i]) hdr->heavy_dynamic_range[i] = get_bits(gbc, 8); if (get_bits1(gbc)) skip_bits(gbc, 8); //skip language code if (get_bits1(gbc)) skip_bits(gbc, 7); //skip audio production information } skip_bits(gbc, 2); //skip copyright bit and original bitstream bit /* skip the timecodes or parse the Alternate Bit Stream Syntax */ if (hdr->bitstream_id != 6) { if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode1 if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode2 } else { if (get_bits1(gbc)) { hdr->preferred_downmix = get_bits(gbc, 2); hdr->center_mix_level_ltrt = get_bits(gbc, 3); hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); hdr->center_mix_level = get_bits(gbc, 3); hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); } if (get_bits1(gbc)) { hdr->dolby_surround_ex_mode = get_bits(gbc, 2); hdr->dolby_headphone_mode = get_bits(gbc, 2); skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1) } } /* skip additional bitstream info */ if (get_bits1(gbc)) { int i = get_bits(gbc, 6); do { skip_bits(gbc, 8); } while (i--); } return 0; } static int eac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { if (hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) return AC3_PARSE_ERROR_FRAME_TYPE; if (hdr->substreamid) return AC3_PARSE_ERROR_FRAME_TYPE; skip_bits(gbc, 5); // skip bitstream id /* volume control params */ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { hdr->dialog_normalization[i] = -get_bits(gbc, 5); hdr->compression_exists[i] = get_bits1(gbc); if (hdr->compression_exists[i]) hdr->heavy_dynamic_range[i] = get_bits(gbc, 8); } /* dependent stream channel map */ if (hdr->frame_type == EAC3_FRAME_TYPE_DEPENDENT) { hdr->channel_map_present = get_bits1(gbc); if (hdr->channel_map_present) { int64_t channel_layout = 0; int channel_map = get_bits(gbc, 16); for (int i = 0; i < 16; i++) if (channel_map & (1 << (EAC3_MAX_CHANNELS - i - 1))) channel_layout |= ff_eac3_custom_channel_map_locations[i][1]; if (av_popcount64(channel_layout) > EAC3_MAX_CHANNELS) { return AC3_PARSE_ERROR_CHANNEL_MAP; } hdr->channel_map = channel_map; } } /* mixing metadata */ if (get_bits1(gbc)) { /* center and surround mix levels */ if (hdr->channel_mode > AC3_CHMODE_STEREO) { hdr->preferred_downmix = get_bits(gbc, 2); if (hdr->channel_mode & 1) { /* if three front channels exist */ hdr->center_mix_level_ltrt = get_bits(gbc, 3); hdr->center_mix_level = get_bits(gbc, 3); } if (hdr->channel_mode & 4) { /* if a surround channel exists */ hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); } } /* lfe mix level */ if (hdr->lfe_on && (hdr->lfe_mix_level_exists = get_bits1(gbc))) { hdr->lfe_mix_level = get_bits(gbc, 5); } /* info for mixing with other streams and substreams */ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) { for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { // TODO: apply program scale factor if (get_bits1(gbc)) { skip_bits(gbc, 6); // skip program scale factor } } if (get_bits1(gbc)) { skip_bits(gbc, 6); // skip external program scale factor } /* skip mixing parameter data */ switch(get_bits(gbc, 2)) { case 1: skip_bits(gbc, 5); break; case 2: skip_bits(gbc, 12); break; case 3: { int mix_data_size = (get_bits(gbc, 5) + 2) << 3; skip_bits_long(gbc, mix_data_size); break; } } /* skip pan information for mono or dual mono source */ if (hdr->channel_mode < AC3_CHMODE_STEREO) { for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { if (get_bits1(gbc)) { /* note: this is not in the ATSC A/52B specification reference: ETSI TS 102 366 V1.1.1 section: E.1.3.1.25 */ skip_bits(gbc, 8); // skip pan mean direction index skip_bits(gbc, 6); // skip reserved paninfo bits } } } /* skip mixing configuration information */ if (get_bits1(gbc)) { for (int i = 0; i < hdr->num_blocks; i++) { if (hdr->num_blocks == 1 || get_bits1(gbc)) { skip_bits(gbc, 5); } } } } } /* informational metadata */ if (get_bits1(gbc)) { hdr->bitstream_mode = get_bits(gbc, 3); skip_bits(gbc, 2); // skip copyright bit and original bitstream bit if (hdr->channel_mode == AC3_CHMODE_STEREO) { hdr->dolby_surround_mode = get_bits(gbc, 2); hdr->dolby_headphone_mode = get_bits(gbc, 2); } if (hdr->channel_mode >= AC3_CHMODE_2F2R) { hdr->dolby_surround_ex_mode = get_bits(gbc, 2); } for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) { if (get_bits1(gbc)) { skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type } } if (hdr->sr_code != EAC3_SR_CODE_REDUCED) { skip_bits1(gbc); // skip source sample rate code } } /* converter synchronization flag If frames are less than six blocks, this bit should be turned on once every 6 blocks to indicate the start of a frame set. reference: RFC 4598, Section 2.1.3 Frame Sets */ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && hdr->num_blocks != 6) { skip_bits1(gbc); // skip converter synchronization flag } /* original frame size code if this stream was converted from AC-3 */ if (hdr->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT && (hdr->num_blocks == 6 || get_bits1(gbc))) { skip_bits(gbc, 6); // skip frame size code } /* additional bitstream info */ if (get_bits1(gbc)) { int addbsil = get_bits(gbc, 6); for (int i = 0; i < addbsil + 1; i++) { if (i == 0) { /* In this 8 bit chunk, the LSB is equal to flag_ec3_extension_type_a which can be used to detect Atmos presence */ skip_bits(gbc, 7); hdr->eac3_extension_type_a = get_bits1(gbc); if (hdr->eac3_extension_type_a) { hdr->complexity_index_type_a = get_bits(gbc, 8); i++; } } else { skip_bits(gbc, 8); // skip additional bit stream info } } } return 0; } int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { int frame_size_code; memset(hdr, 0, sizeof(*hdr)); hdr->sync_word = get_bits(gbc, 16); if(hdr->sync_word != 0x0B77) return AC3_PARSE_ERROR_SYNC; /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */ hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F; if(hdr->bitstream_id > 16) return AC3_PARSE_ERROR_BSID; hdr->num_blocks = 6; hdr->ac3_bit_rate_code = -1; /* set default mix levels */ hdr->center_mix_level = 5; // -4.5dB hdr->surround_mix_level = 6; // -6.0dB /* set default dolby surround mode */ hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED; if(hdr->bitstream_id <= 10) { /* Normal AC-3 */ hdr->crc1 = get_bits(gbc, 16); hdr->sr_code = get_bits(gbc, 2); if(hdr->sr_code == 3) return AC3_PARSE_ERROR_SAMPLE_RATE; frame_size_code = get_bits(gbc, 6); if(frame_size_code > 37) return AC3_PARSE_ERROR_FRAME_SIZE; hdr->ac3_bit_rate_code = (frame_size_code >> 1); skip_bits(gbc, 5); // skip bsid, already got it hdr->bitstream_mode = get_bits(gbc, 3); hdr->channel_mode = get_bits(gbc, 3); if(hdr->channel_mode == AC3_CHMODE_STEREO) { hdr->dolby_surround_mode = get_bits(gbc, 2); } else { if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) hdr-> center_mix_level = center_levels[get_bits(gbc, 2)]; if(hdr->channel_mode & 4) hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)]; } hdr->lfe_on = get_bits1(gbc); hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8; hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift; hdr->bit_rate = (ff_ac3_bitrate_tab[hdr->ac3_bit_rate_code] * 1000) >> hdr->sr_shift; hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2; hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT; hdr->substreamid = 0; int ret = ac3_parse_header(gbc, hdr); if (ret < 0) return ret; } else { /* Enhanced AC-3 */ hdr->crc1 = 0; hdr->frame_type = get_bits(gbc, 2); if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) return AC3_PARSE_ERROR_FRAME_TYPE; hdr->substreamid = get_bits(gbc, 3); hdr->frame_size = (get_bits(gbc, 11) + 1) << 1; if(hdr->frame_size < AC3_HEADER_SIZE) return AC3_PARSE_ERROR_FRAME_SIZE; hdr->sr_code = get_bits(gbc, 2); if (hdr->sr_code == 3) { int sr_code2 = get_bits(gbc, 2); if(sr_code2 == 3) return AC3_PARSE_ERROR_SAMPLE_RATE; hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2; hdr->sr_shift = 1; } else { hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)]; hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code]; hdr->sr_shift = 0; } hdr->channel_mode = get_bits(gbc, 3); hdr->lfe_on = get_bits1(gbc); hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate / (hdr->num_blocks * 256); hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on; int ret = eac3_parse_header(gbc, hdr); if (ret < 0) return ret; } hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode]; if (hdr->lfe_on) hdr->channel_layout |= AV_CH_LOW_FREQUENCY; return 0; } // TODO: Better way to pass AC3HeaderInfo fields to mov muxer. int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size) { GetBitContext gb; AC3HeaderInfo *hdr; int err; if (!*phdr) *phdr = av_mallocz(sizeof(AC3HeaderInfo)); if (!*phdr) return AVERROR(ENOMEM); hdr = *phdr; err = init_get_bits8(&gb, buf, size); if (err < 0) return AVERROR_INVALIDDATA; err = ff_ac3_parse_header(&gb, hdr); if (err < 0) return AVERROR_INVALIDDATA; return get_bits_count(&gb); } int av_ac3_parse_header(const uint8_t *buf, size_t size, uint8_t *bitstream_id, uint16_t *frame_size) { GetBitContext gb; AC3HeaderInfo hdr; uint8_t tmp[32 + AV_INPUT_BUFFER_PADDING_SIZE]; int err; size = FFMIN(32, size); memcpy(tmp, buf, size); memset(tmp + size, 0, AV_INPUT_BUFFER_PADDING_SIZE); err = init_get_bits8(&gb, tmp, size); if (err < 0) return AVERROR_INVALIDDATA; err = ff_ac3_parse_header(&gb, &hdr); if (err < 0) return AVERROR_INVALIDDATA; *bitstream_id = hdr.bitstream_id; *frame_size = hdr.frame_size; return 0; } static int ac3_sync(uint64_t state, int *need_next_header, int *new_frame_start) { int err; union { uint64_t u64; uint8_t u8[8 + AV_INPUT_BUFFER_PADDING_SIZE]; } tmp = { av_be2ne64(state) }; AC3HeaderInfo hdr; GetBitContext gbc; if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) { FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]); FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]); FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]); } init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54); err = ff_ac3_parse_header(&gbc, &hdr); if(err < 0) return 0; *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT); *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT); return hdr.frame_size; } static av_cold int ac3_parse_init(AVCodecParserContext *s1) { AACAC3ParseContext *s = s1->priv_data; s->header_size = AC3_HEADER_SIZE; s->crc_ctx = av_crc_get_table(AV_CRC_16_ANSI); s->sync = ac3_sync; return 0; } const AVCodecParser ff_ac3_parser = { .codec_ids = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 }, .priv_data_size = sizeof(AACAC3ParseContext), .parser_init = ac3_parse_init, .parser_parse = ff_aac_ac3_parse, .parser_close = ff_parse_close, }; #else int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size) { return AVERROR(ENOSYS); } int av_ac3_parse_header(const uint8_t *buf, size_t size, uint8_t *bitstream_id, uint16_t *frame_size) { return AVERROR(ENOSYS); }