/* * 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.h"#include "config_components.h" #include "libavutil/channel_layout.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;} 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 AAC_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 AAC_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 AAC_AC3_PARSE_ERROR_SAMPLE_RATE;         frame_size_code = get_bits(gbc, 6);        if(frame_size_code > 37)            return AAC_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;    } else {        /* Enhanced AC-3 */        hdr->crc1 = 0;        hdr->frame_type = get_bits(gbc, 2);        if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)            return AAC_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 AAC_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 AAC_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;    }    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;    int err;     init_get_bits8(&gb, buf, size);    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);}#endif