198 lines
6.4 KiB
C
198 lines
6.4 KiB
C
/*
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* AC-3 parser
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* Copyright (c) 2003 Fabrice Bellard
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* Copyright (c) 2003 Michael Niedermayer
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*
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* This file is part of Libav.
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*
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* Libav 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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* Libav 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 Libav; 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 "libavutil/channel_layout.h"
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#include "parser.h"
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#include "ac3_parser.h"
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#include "aac_ac3_parser.h"
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#include "get_bits.h"
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#define AC3_HEADER_SIZE 7
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static const uint8_t eac3_blocks[4] = {
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1, 2, 3, 6
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};
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/**
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* Table for center mix levels
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* reference: Section 5.4.2.4 cmixlev
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*/
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static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
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/**
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* Table for surround mix levels
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* reference: Section 5.4.2.5 surmixlev
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*/
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static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
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int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
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{
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int frame_size_code;
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memset(hdr, 0, sizeof(*hdr));
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hdr->sync_word = get_bits(gbc, 16);
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if(hdr->sync_word != 0x0B77)
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return AAC_AC3_PARSE_ERROR_SYNC;
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/* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
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hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;
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if(hdr->bitstream_id > 16)
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return AAC_AC3_PARSE_ERROR_BSID;
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hdr->num_blocks = 6;
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/* set default mix levels */
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hdr->center_mix_level = 5; // -4.5dB
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hdr->surround_mix_level = 6; // -6.0dB
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/* set default dolby surround mode */
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hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
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if(hdr->bitstream_id <= 10) {
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/* Normal AC-3 */
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hdr->crc1 = get_bits(gbc, 16);
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hdr->sr_code = get_bits(gbc, 2);
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if(hdr->sr_code == 3)
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return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
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frame_size_code = get_bits(gbc, 6);
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if(frame_size_code > 37)
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return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
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skip_bits(gbc, 5); // skip bsid, already got it
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hdr->bitstream_mode = get_bits(gbc, 3);
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hdr->channel_mode = get_bits(gbc, 3);
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if(hdr->channel_mode == AC3_CHMODE_STEREO) {
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hdr->dolby_surround_mode = get_bits(gbc, 2);
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} else {
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if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
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hdr-> center_mix_level = center_levels[get_bits(gbc, 2)];
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if(hdr->channel_mode & 4)
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hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
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}
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hdr->lfe_on = get_bits1(gbc);
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hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
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hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
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hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
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hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
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hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
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hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
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hdr->substreamid = 0;
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} else {
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/* Enhanced AC-3 */
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hdr->crc1 = 0;
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hdr->frame_type = get_bits(gbc, 2);
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if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
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return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
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hdr->substreamid = get_bits(gbc, 3);
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hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
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if(hdr->frame_size < AC3_HEADER_SIZE)
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return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
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hdr->sr_code = get_bits(gbc, 2);
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if (hdr->sr_code == 3) {
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int sr_code2 = get_bits(gbc, 2);
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if(sr_code2 == 3)
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return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
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hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
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hdr->sr_shift = 1;
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} else {
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hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
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hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
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hdr->sr_shift = 0;
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}
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hdr->channel_mode = get_bits(gbc, 3);
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hdr->lfe_on = get_bits1(gbc);
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hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
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(hdr->num_blocks * 256.0));
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hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
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}
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hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode];
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if (hdr->lfe_on)
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hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
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return 0;
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}
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static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
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int *need_next_header, int *new_frame_start)
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{
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int err;
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union {
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uint64_t u64;
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uint8_t u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
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} tmp = { av_be2ne64(state) };
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AC3HeaderInfo hdr;
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GetBitContext gbc;
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init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
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err = avpriv_ac3_parse_header(&gbc, &hdr);
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if(err < 0)
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return 0;
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hdr_info->sample_rate = hdr.sample_rate;
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hdr_info->bit_rate = hdr.bit_rate;
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hdr_info->channels = hdr.channels;
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hdr_info->channel_layout = hdr.channel_layout;
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hdr_info->samples = hdr.num_blocks * 256;
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hdr_info->service_type = hdr.bitstream_mode;
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if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
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hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
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if(hdr.bitstream_id>10)
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hdr_info->codec_id = AV_CODEC_ID_EAC3;
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else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
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hdr_info->codec_id = AV_CODEC_ID_AC3;
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*need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
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*new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
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return hdr.frame_size;
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}
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static av_cold int ac3_parse_init(AVCodecParserContext *s1)
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{
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AACAC3ParseContext *s = s1->priv_data;
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s->header_size = AC3_HEADER_SIZE;
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s->sync = ac3_sync;
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return 0;
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}
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AVCodecParser ff_ac3_parser = {
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.codec_ids = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
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.priv_data_size = sizeof(AACAC3ParseContext),
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.parser_init = ac3_parse_init,
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.parser_parse = ff_aac_ac3_parse,
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.parser_close = ff_parse_close,
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};
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