/* * 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 "parser.h"#include "ac3_parser.h"#include "aac_ac3_parser.h"#include "get_bits.h"  #define AC3_HEADER_SIZE 7  static const uint8_t eac3_blocks[4] = {    1, 2, 3, 6};  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;     /* set default mix levels */    hdr->center_mix_level   = 1;  // -4.5dB    hdr->surround_mix_level = 1;  // -6.0dB     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;         skip_bits(gbc, 5); // skip bsid, already got it         skip_bits(gbc, 3); // skip bitstream mode        hdr->channel_mode = get_bits(gbc, 3);         if(hdr->channel_mode == AC3_CHMODE_STEREO) {            skip_bits(gbc, 2); // skip dsurmod        } else {            if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)                hdr->center_mix_level = get_bits(gbc, 2);            if(hdr->channel_mode & 4)                hdr->surround_mix_level = 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[frame_size_code>>1] * 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 = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /                        (hdr->num_blocks * 256.0));        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 |= CH_LOW_FREQUENCY;     return 0;} int ff_ac3_parse_header_full(GetBitContext *gbc, AC3HeaderInfo *hdr){    int ret, i;    ret = ff_ac3_parse_header(gbc, hdr);    if(!ret){        if(hdr->bitstream_id>10){            /* Enhanced AC-3 */            skip_bits(gbc, 5); // skip bitstream id             /* skip dialog normalization and compression gain */            for (i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {                skip_bits(gbc, 5); // skip dialog normalization                if (get_bits1(gbc)) {                    skip_bits(gbc, 8); //skip Compression gain word                }            }            /* dependent stream channel map */            if (hdr->frame_type == EAC3_FRAME_TYPE_DEPENDENT && get_bits1(gbc)) {                    hdr->channel_map = get_bits(gbc, 16); //custom channel map                    return 0;            }        }        //default channel map based on acmod and lfeon        hdr->channel_map = ff_eac3_default_chmap[hdr->channel_mode];        if(hdr->lfe_on)            hdr->channel_map |= AC3_CHMAP_LFE;    }    return ret;} static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,        int *need_next_header, int *new_frame_start){    int err;    union {        uint64_t u64;        uint8_t  u8[8];    } tmp = { be2me_64(state) };    AC3HeaderInfo hdr;    GetBitContext gbc;     init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);    err = ff_ac3_parse_header(&gbc, &hdr);     if(err < 0)        return 0;     hdr_info->sample_rate = hdr.sample_rate;    hdr_info->bit_rate = hdr.bit_rate;    hdr_info->channels = hdr.channels;    hdr_info->channel_layout = hdr.channel_layout;    hdr_info->samples = hdr.num_blocks * 256;    if(hdr.bitstream_id>10)        hdr_info->codec_id = CODEC_ID_EAC3;    else        hdr_info->codec_id = CODEC_ID_AC3;     *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);    *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);    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->sync = ac3_sync;    return 0;}  AVCodecParser ac3_parser = {    { CODEC_ID_AC3, CODEC_ID_EAC3 },    sizeof(AACAC3ParseContext),    ac3_parse_init,    ff_aac_ac3_parse,    ff_parse_close,};