From 55736cfbd22e0a7c10a85eb0d5cc7a22bf841322 Mon Sep 17 00:00:00 2001 From: Bartlomiej Wolowiec Date: Tue, 22 Apr 2008 11:14:01 +0000 Subject: change ff_ac3_parse_header() to take a GetBitContext instead of const char* Originally committed as revision 12922 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/ac3_parser.c | 73 +++++++++++++++++++++++++++++-------------------- 1 file changed, 44 insertions(+), 29 deletions(-) (limited to 'libavcodec/ac3_parser.c') diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c index f0b640dc4a..471fb4f6e2 100644 --- a/libavcodec/ac3_parser.c +++ b/libavcodec/ac3_parser.c @@ -33,51 +33,64 @@ 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] = { 2, 3, 4, 3 }; + +/** + * Table for surround mix levels + * reference: Section 5.4.2.5 surmixlev + */ +static const uint8_t surround_levels[4] = { 2, 4, 0, 4 }; -int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr) + +int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr) { - GetBitContext gbc; int frame_size_code; int num_blocks; memset(hdr, 0, sizeof(*hdr)); - init_get_bits(&gbc, buf, 54); - - hdr->sync_word = get_bits(&gbc, 16); + 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; + hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F; if(hdr->bitstream_id > 16) return AC3_PARSE_ERROR_BSID; if(hdr->bitstream_id <= 10) { /* Normal AC-3 */ - hdr->crc1 = get_bits(&gbc, 16); - hdr->sr_code = get_bits(&gbc, 2); + 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); + frame_size_code = get_bits(gbc, 6); if(frame_size_code > 37) return AC3_PARSE_ERROR_FRAME_SIZE; - skip_bits(&gbc, 5); // skip bsid, already got it + skip_bits(gbc, 5); // skip bsid, already got it + + skip_bits(gbc, 3); // skip bitstream mode + hdr->channel_mode = get_bits(gbc, 3); + + /* set default mix levels */ + hdr->center_mix_level = 3; // -4.5dB + hdr->surround_mix_level = 4; // -6.0dB - skip_bits(&gbc, 3); // skip bitstream mode - hdr->channel_mode = get_bits(&gbc, 3); - if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) { - skip_bits(&gbc, 2); // skip center mix level - } - if(hdr->channel_mode & 4) { - skip_bits(&gbc, 2); // skip surround mix level - } if(hdr->channel_mode == AC3_CHMODE_STEREO) { - skip_bits(&gbc, 2); // skip dolby surround mode + skip_bits(gbc, 2); // skip dsurmod + } 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->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; @@ -88,32 +101,32 @@ int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr) } else { /* Enhanced AC-3 */ hdr->crc1 = 0; - hdr->frame_type = get_bits(&gbc, 2); + hdr->frame_type = get_bits(gbc, 2); if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED) return AC3_PARSE_ERROR_FRAME_TYPE; - skip_bits(&gbc, 3); // skip substream id + skip_bits(gbc, 3); // skip substream id - hdr->frame_size = (get_bits(&gbc, 11) + 1) << 1; + 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); + hdr->sr_code = get_bits(gbc, 2); if (hdr->sr_code == 3) { - int sr_code2 = get_bits(&gbc, 2); + 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; num_blocks = 6; } else { - num_blocks = eac3_blocks[get_bits(&gbc, 2)]; + 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->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 / (num_blocks * 256.0)); @@ -129,8 +142,10 @@ static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info, int err; uint64_t tmp = be2me_64(state); AC3HeaderInfo hdr; + GetBitContext gbc; - err = ff_ac3_parse_header(((uint8_t *)&tmp)+8-AC3_HEADER_SIZE, &hdr); + init_get_bits(&gbc, ((uint8_t *)&tmp)+8-AC3_HEADER_SIZE, 54); + err = ff_ac3_parse_header(&gbc, &hdr); if(err < 0) return 0; -- cgit v1.2.3