| /* |
| * 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 "bitstream.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; |
| } |
| |
| 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->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, |
| }; |
