| /* |
| * AC-3 Audio Decoder |
| * This code was developed as part of Google Summer of Code 2006. |
| * E-AC-3 support was added as part of Google Summer of Code 2007. |
| * |
| * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com) |
| * Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> |
| * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com> |
| * |
| * 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 <stdio.h> |
| #include <stddef.h> |
| #include <math.h> |
| #include <string.h> |
| |
| #include "libavutil/crc.h" |
| #include "internal.h" |
| #include "aac_ac3_parser.h" |
| #include "ac3_parser.h" |
| #include "ac3dec.h" |
| #include "ac3dec_data.h" |
| |
| /** Large enough for maximum possible frame size when the specification limit is ignored */ |
| #define AC3_FRAME_BUFFER_SIZE 32768 |
| |
| /** |
| * table for ungrouping 3 values in 7 bits. |
| * used for exponents and bap=2 mantissas |
| */ |
| static uint8_t ungroup_3_in_7_bits_tab[128][3]; |
| |
| |
| /** tables for ungrouping mantissas */ |
| static int b1_mantissas[32][3]; |
| static int b2_mantissas[128][3]; |
| static int b3_mantissas[8]; |
| static int b4_mantissas[128][2]; |
| static int b5_mantissas[16]; |
| |
| /** |
| * Quantization table: levels for symmetric. bits for asymmetric. |
| * reference: Table 7.18 Mapping of bap to Quantizer |
| */ |
| static const uint8_t quantization_tab[16] = { |
| 0, 3, 5, 7, 11, 15, |
| 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 |
| }; |
| |
| /** dynamic range table. converts codes to scale factors. */ |
| static float dynamic_range_tab[256]; |
| |
| /** Adjustments in dB gain */ |
| #define LEVEL_PLUS_3DB 1.4142135623730950 |
| #define LEVEL_PLUS_1POINT5DB 1.1892071150027209 |
| #define LEVEL_MINUS_1POINT5DB 0.8408964152537145 |
| #define LEVEL_MINUS_3DB 0.7071067811865476 |
| #define LEVEL_MINUS_4POINT5DB 0.5946035575013605 |
| #define LEVEL_MINUS_6DB 0.5000000000000000 |
| #define LEVEL_MINUS_9DB 0.3535533905932738 |
| #define LEVEL_ZERO 0.0000000000000000 |
| #define LEVEL_ONE 1.0000000000000000 |
| |
| static const float gain_levels[9] = { |
| LEVEL_PLUS_3DB, |
| LEVEL_PLUS_1POINT5DB, |
| LEVEL_ONE, |
| LEVEL_MINUS_1POINT5DB, |
| LEVEL_MINUS_3DB, |
| LEVEL_MINUS_4POINT5DB, |
| LEVEL_MINUS_6DB, |
| LEVEL_ZERO, |
| LEVEL_MINUS_9DB |
| }; |
| |
| /** |
| * 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 }; |
| |
| /** |
| * Table for default stereo downmixing coefficients |
| * reference: Section 7.8.2 Downmixing Into Two Channels |
| */ |
| static const uint8_t ac3_default_coeffs[8][5][2] = { |
| { { 2, 7 }, { 7, 2 }, }, |
| { { 4, 4 }, }, |
| { { 2, 7 }, { 7, 2 }, }, |
| { { 2, 7 }, { 5, 5 }, { 7, 2 }, }, |
| { { 2, 7 }, { 7, 2 }, { 6, 6 }, }, |
| { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, }, |
| { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, |
| { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, |
| }; |
| |
| /** |
| * Symmetrical Dequantization |
| * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization |
| * Tables 7.19 to 7.23 |
| */ |
| static inline int |
| symmetric_dequant(int code, int levels) |
| { |
| return ((code - (levels >> 1)) << 24) / levels; |
| } |
| |
| /* |
| * Initialize tables at runtime. |
| */ |
| static av_cold void ac3_tables_init(void) |
| { |
| int i; |
| |
| /* generate table for ungrouping 3 values in 7 bits |
| reference: Section 7.1.3 Exponent Decoding */ |
| for(i=0; i<128; i++) { |
| ungroup_3_in_7_bits_tab[i][0] = i / 25; |
| ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5; |
| ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5; |
| } |
| |
| /* generate grouped mantissa tables |
| reference: Section 7.3.5 Ungrouping of Mantissas */ |
| for(i=0; i<32; i++) { |
| /* bap=1 mantissas */ |
| b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3); |
| b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3); |
| b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3); |
| } |
| for(i=0; i<128; i++) { |
| /* bap=2 mantissas */ |
| b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5); |
| b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5); |
| b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5); |
| |
| /* bap=4 mantissas */ |
| b4_mantissas[i][0] = symmetric_dequant(i / 11, 11); |
| b4_mantissas[i][1] = symmetric_dequant(i % 11, 11); |
| } |
| /* generate ungrouped mantissa tables |
| reference: Tables 7.21 and 7.23 */ |
| for(i=0; i<7; i++) { |
| /* bap=3 mantissas */ |
| b3_mantissas[i] = symmetric_dequant(i, 7); |
| } |
| for(i=0; i<15; i++) { |
| /* bap=5 mantissas */ |
| b5_mantissas[i] = symmetric_dequant(i, 15); |
| } |
| |
| /* generate dynamic range table |
| reference: Section 7.7.1 Dynamic Range Control */ |
| for(i=0; i<256; i++) { |
| int v = (i >> 5) - ((i >> 7) << 3) - 5; |
| dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20); |
| } |
| } |
| |
| |
| /** |
| * AVCodec initialization |
| */ |
| static av_cold int ac3_decode_init(AVCodecContext *avctx) |
| { |
| AC3DecodeContext *s = avctx->priv_data; |
| s->avctx = avctx; |
| |
| ac3_common_init(); |
| ac3_tables_init(); |
| ff_mdct_init(&s->imdct_256, 8, 1); |
| ff_mdct_init(&s->imdct_512, 9, 1); |
| ff_kbd_window_init(s->window, 5.0, 256); |
| dsputil_init(&s->dsp, avctx); |
| av_lfg_init(&s->dith_state, 0); |
| |
| /* set bias values for float to int16 conversion */ |
| if(s->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) { |
| s->add_bias = 385.0f; |
| s->mul_bias = 1.0f; |
| } else { |
| s->add_bias = 0.0f; |
| s->mul_bias = 32767.0f; |
| } |
| |
| /* allow downmixing to stereo or mono */ |
| if (avctx->channels > 0 && avctx->request_channels > 0 && |
| avctx->request_channels < avctx->channels && |
| avctx->request_channels <= 2) { |
| avctx->channels = avctx->request_channels; |
| } |
| s->downmixed = 1; |
| |
| /* allocate context input buffer */ |
| if (avctx->error_recognition >= FF_ER_CAREFUL) { |
| s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE); |
| if (!s->input_buffer) |
| return AVERROR_NOMEM; |
| } |
| |
| avctx->sample_fmt = SAMPLE_FMT_S16; |
| return 0; |
| } |
| |
| /** |
| * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream. |
| * GetBitContext within AC3DecodeContext must point to |
| * the start of the synchronized AC-3 bitstream. |
| */ |
| static int ac3_parse_header(AC3DecodeContext *s) |
| { |
| GetBitContext *gbc = &s->gbc; |
| int i; |
| |
| /* read the rest of the bsi. read twice for dual mono mode. */ |
| i = !(s->channel_mode); |
| do { |
| skip_bits(gbc, 5); // skip dialog normalization |
| if (get_bits1(gbc)) |
| skip_bits(gbc, 8); //skip compression |
| if (get_bits1(gbc)) |
| skip_bits(gbc, 8); //skip language code |
| if (get_bits1(gbc)) |
| skip_bits(gbc, 7); //skip audio production information |
| } while (i--); |
| |
| skip_bits(gbc, 2); //skip copyright bit and original bitstream bit |
| |
| /* skip the timecodes (or extra bitstream information for Alternate Syntax) |
| TODO: read & use the xbsi1 downmix levels */ |
| if (get_bits1(gbc)) |
| skip_bits(gbc, 14); //skip timecode1 / xbsi1 |
| if (get_bits1(gbc)) |
| skip_bits(gbc, 14); //skip timecode2 / xbsi2 |
| |
| /* skip additional bitstream info */ |
| if (get_bits1(gbc)) { |
| i = get_bits(gbc, 6); |
| do { |
| skip_bits(gbc, 8); |
| } while(i--); |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * Common function to parse AC-3 or E-AC-3 frame header |
| */ |
| static int parse_frame_header(AC3DecodeContext *s) |
| { |
| AC3HeaderInfo hdr; |
| int err; |
| |
| err = ff_ac3_parse_header(&s->gbc, &hdr); |
| if(err) |
| return err; |
| |
| /* get decoding parameters from header info */ |
| s->bit_alloc_params.sr_code = hdr.sr_code; |
| s->channel_mode = hdr.channel_mode; |
| s->lfe_on = hdr.lfe_on; |
| s->bit_alloc_params.sr_shift = hdr.sr_shift; |
| s->sample_rate = hdr.sample_rate; |
| s->bit_rate = hdr.bit_rate; |
| s->channels = hdr.channels; |
| s->fbw_channels = s->channels - s->lfe_on; |
| s->lfe_ch = s->fbw_channels + 1; |
| s->frame_size = hdr.frame_size; |
| s->center_mix_level = hdr.center_mix_level; |
| s->surround_mix_level = hdr.surround_mix_level; |
| s->num_blocks = hdr.num_blocks; |
| s->frame_type = hdr.frame_type; |
| s->substreamid = hdr.substreamid; |
| |
| if(s->lfe_on) { |
| s->start_freq[s->lfe_ch] = 0; |
| s->end_freq[s->lfe_ch] = 7; |
| s->num_exp_groups[s->lfe_ch] = 2; |
| s->channel_in_cpl[s->lfe_ch] = 0; |
| } |
| |
| if (hdr.bitstream_id <= 10) { |
| s->eac3 = 0; |
| s->snr_offset_strategy = 2; |
| s->block_switch_syntax = 1; |
| s->dither_flag_syntax = 1; |
| s->bit_allocation_syntax = 1; |
| s->fast_gain_syntax = 0; |
| s->first_cpl_leak = 0; |
| s->dba_syntax = 1; |
| s->skip_syntax = 1; |
| memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht)); |
| return ac3_parse_header(s); |
| } else { |
| s->eac3 = 1; |
| return ff_eac3_parse_header(s); |
| } |
| } |
| |
| /** |
| * Set stereo downmixing coefficients based on frame header info. |
| * reference: Section 7.8.2 Downmixing Into Two Channels |
| */ |
| static void set_downmix_coeffs(AC3DecodeContext *s) |
| { |
| int i; |
| float cmix = gain_levels[center_levels[s->center_mix_level]]; |
| float smix = gain_levels[surround_levels[s->surround_mix_level]]; |
| float norm0, norm1; |
| |
| for(i=0; i<s->fbw_channels; i++) { |
| s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]]; |
| s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]]; |
| } |
| if(s->channel_mode > 1 && s->channel_mode & 1) { |
| s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix; |
| } |
| if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) { |
| int nf = s->channel_mode - 2; |
| s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB; |
| } |
| if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) { |
| int nf = s->channel_mode - 4; |
| s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix; |
| } |
| |
| /* renormalize */ |
| norm0 = norm1 = 0.0; |
| for(i=0; i<s->fbw_channels; i++) { |
| norm0 += s->downmix_coeffs[i][0]; |
| norm1 += s->downmix_coeffs[i][1]; |
| } |
| norm0 = 1.0f / norm0; |
| norm1 = 1.0f / norm1; |
| for(i=0; i<s->fbw_channels; i++) { |
| s->downmix_coeffs[i][0] *= norm0; |
| s->downmix_coeffs[i][1] *= norm1; |
| } |
| |
| if(s->output_mode == AC3_CHMODE_MONO) { |
| for(i=0; i<s->fbw_channels; i++) |
| s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB; |
| } |
| } |
| |
| /** |
| * Decode the grouped exponents according to exponent strategy. |
| * reference: Section 7.1.3 Exponent Decoding |
| */ |
| static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps, |
| uint8_t absexp, int8_t *dexps) |
| { |
| int i, j, grp, group_size; |
| int dexp[256]; |
| int expacc, prevexp; |
| |
| /* unpack groups */ |
| group_size = exp_strategy + (exp_strategy == EXP_D45); |
| for(grp=0,i=0; grp<ngrps; grp++) { |
| expacc = get_bits(gbc, 7); |
| dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0]; |
| dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1]; |
| dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2]; |
| } |
| |
| /* convert to absolute exps and expand groups */ |
| prevexp = absexp; |
| for(i=0,j=0; i<ngrps*3; i++) { |
| prevexp += dexp[i] - 2; |
| if (prevexp > 24U) |
| return -1; |
| switch (group_size) { |
| case 4: dexps[j++] = prevexp; |
| dexps[j++] = prevexp; |
| case 2: dexps[j++] = prevexp; |
| case 1: dexps[j++] = prevexp; |
| } |
| } |
| return 0; |
| } |
| |
| /** |
| * Generate transform coefficients for each coupled channel in the coupling |
| * range using the coupling coefficients and coupling coordinates. |
| * reference: Section 7.4.3 Coupling Coordinate Format |
| */ |
| static void calc_transform_coeffs_cpl(AC3DecodeContext *s) |
| { |
| int i, j, ch, bnd, subbnd; |
| |
| subbnd = -1; |
| i = s->start_freq[CPL_CH]; |
| for(bnd=0; bnd<s->num_cpl_bands; bnd++) { |
| do { |
| subbnd++; |
| for(j=0; j<12; j++) { |
| for(ch=1; ch<=s->fbw_channels; ch++) { |
| if(s->channel_in_cpl[ch]) { |
| s->fixed_coeffs[ch][i] = ((int64_t)s->fixed_coeffs[CPL_CH][i] * (int64_t)s->cpl_coords[ch][bnd]) >> 23; |
| if (ch == 2 && s->phase_flags[bnd]) |
| s->fixed_coeffs[ch][i] = -s->fixed_coeffs[ch][i]; |
| } |
| } |
| i++; |
| } |
| } while(s->cpl_band_struct[subbnd]); |
| } |
| } |
| |
| /** |
| * Grouped mantissas for 3-level 5-level and 11-level quantization |
| */ |
| typedef struct { |
| int b1_mant[2]; |
| int b2_mant[2]; |
| int b4_mant; |
| int b1; |
| int b2; |
| int b4; |
| } mant_groups; |
| |
| /** |
| * Decode the transform coefficients for a particular channel |
| * reference: Section 7.3 Quantization and Decoding of Mantissas |
| */ |
| static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m) |
| { |
| int start_freq = s->start_freq[ch_index]; |
| int end_freq = s->end_freq[ch_index]; |
| uint8_t *baps = s->bap[ch_index]; |
| int8_t *exps = s->dexps[ch_index]; |
| int *coeffs = s->fixed_coeffs[ch_index]; |
| GetBitContext *gbc = &s->gbc; |
| int freq; |
| |
| for(freq = start_freq; freq < end_freq; freq++){ |
| int bap = baps[freq]; |
| int mantissa; |
| switch(bap){ |
| case 0: |
| mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000; |
| break; |
| case 1: |
| if(m->b1){ |
| m->b1--; |
| mantissa = m->b1_mant[m->b1]; |
| } |
| else{ |
| int bits = get_bits(gbc, 5); |
| mantissa = b1_mantissas[bits][0]; |
| m->b1_mant[1] = b1_mantissas[bits][1]; |
| m->b1_mant[0] = b1_mantissas[bits][2]; |
| m->b1 = 2; |
| } |
| break; |
| case 2: |
| if(m->b2){ |
| m->b2--; |
| mantissa = m->b2_mant[m->b2]; |
| } |
| else{ |
| int bits = get_bits(gbc, 7); |
| mantissa = b2_mantissas[bits][0]; |
| m->b2_mant[1] = b2_mantissas[bits][1]; |
| m->b2_mant[0] = b2_mantissas[bits][2]; |
| m->b2 = 2; |
| } |
| break; |
| case 3: |
| mantissa = b3_mantissas[get_bits(gbc, 3)]; |
| break; |
| case 4: |
| if(m->b4){ |
| m->b4 = 0; |
| mantissa = m->b4_mant; |
| } |
| else{ |
| int bits = get_bits(gbc, 7); |
| mantissa = b4_mantissas[bits][0]; |
| m->b4_mant = b4_mantissas[bits][1]; |
| m->b4 = 1; |
| } |
| break; |
| case 5: |
| mantissa = b5_mantissas[get_bits(gbc, 4)]; |
| break; |
| default: /* 6 to 15 */ |
| mantissa = get_bits(gbc, quantization_tab[bap]); |
| /* Shift mantissa and sign-extend it. */ |
| mantissa = (mantissa << (32-quantization_tab[bap]))>>8; |
| break; |
| } |
| coeffs[freq] = mantissa >> exps[freq]; |
| } |
| } |
| |
| /** |
| * Remove random dithering from coefficients with zero-bit mantissas |
| * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0) |
| */ |
| static void remove_dithering(AC3DecodeContext *s) { |
| int ch, i; |
| int end=0; |
| int *coeffs; |
| uint8_t *bap; |
| |
| for(ch=1; ch<=s->fbw_channels; ch++) { |
| if(!s->dither_flag[ch]) { |
| coeffs = s->fixed_coeffs[ch]; |
| bap = s->bap[ch]; |
| if(s->channel_in_cpl[ch]) |
| end = s->start_freq[CPL_CH]; |
| else |
| end = s->end_freq[ch]; |
| for(i=0; i<end; i++) { |
| if(!bap[i]) |
| coeffs[i] = 0; |
| } |
| if(s->channel_in_cpl[ch]) { |
| bap = s->bap[CPL_CH]; |
| for(; i<s->end_freq[CPL_CH]; i++) { |
| if(!bap[i]) |
| coeffs[i] = 0; |
| } |
| } |
| } |
| } |
| } |
| |
| static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch, |
| mant_groups *m) |
| { |
| if (!s->channel_uses_aht[ch]) { |
| ac3_decode_transform_coeffs_ch(s, ch, m); |
| } else { |
| /* if AHT is used, mantissas for all blocks are encoded in the first |
| block of the frame. */ |
| int bin; |
| if (!blk) |
| ff_eac3_decode_transform_coeffs_aht_ch(s, ch); |
| for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) { |
| s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin]; |
| } |
| } |
| } |
| |
| /** |
| * Decode the transform coefficients. |
| */ |
| static void decode_transform_coeffs(AC3DecodeContext *s, int blk) |
| { |
| int ch, end; |
| int got_cplchan = 0; |
| mant_groups m; |
| |
| m.b1 = m.b2 = m.b4 = 0; |
| |
| for (ch = 1; ch <= s->channels; ch++) { |
| /* transform coefficients for full-bandwidth channel */ |
| decode_transform_coeffs_ch(s, blk, ch, &m); |
| /* tranform coefficients for coupling channel come right after the |
| coefficients for the first coupled channel*/ |
| if (s->channel_in_cpl[ch]) { |
| if (!got_cplchan) { |
| decode_transform_coeffs_ch(s, blk, CPL_CH, &m); |
| calc_transform_coeffs_cpl(s); |
| got_cplchan = 1; |
| } |
| end = s->end_freq[CPL_CH]; |
| } else { |
| end = s->end_freq[ch]; |
| } |
| do |
| s->fixed_coeffs[ch][end] = 0; |
| while(++end < 256); |
| } |
| |
| /* zero the dithered coefficients for appropriate channels */ |
| remove_dithering(s); |
| } |
| |
| /** |
| * Stereo rematrixing. |
| * reference: Section 7.5.4 Rematrixing : Decoding Technique |
| */ |
| static void do_rematrixing(AC3DecodeContext *s) |
| { |
| int bnd, i; |
| int end, bndend; |
| int tmp0, tmp1; |
| |
| end = FFMIN(s->end_freq[1], s->end_freq[2]); |
| |
| for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) { |
| if(s->rematrixing_flags[bnd]) { |
| bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]); |
| for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) { |
| tmp0 = s->fixed_coeffs[1][i]; |
| tmp1 = s->fixed_coeffs[2][i]; |
| s->fixed_coeffs[1][i] = tmp0 + tmp1; |
| s->fixed_coeffs[2][i] = tmp0 - tmp1; |
| } |
| } |
| } |
| } |
| |
| /** |
| * Inverse MDCT Transform. |
| * Convert frequency domain coefficients to time-domain audio samples. |
| * reference: Section 7.9.4 Transformation Equations |
| */ |
| static inline void do_imdct(AC3DecodeContext *s, int channels) |
| { |
| int ch; |
| float add_bias = s->add_bias; |
| if(s->out_channels==1 && channels>1) |
| add_bias *= LEVEL_MINUS_3DB; // compensate for the gain in downmix |
| |
| for (ch=1; ch<=channels; ch++) { |
| if (s->block_switch[ch]) { |
| int i; |
| float *x = s->tmp_output+128; |
| for(i=0; i<128; i++) |
| x[i] = s->transform_coeffs[ch][2*i]; |
| ff_imdct_half(&s->imdct_256, s->tmp_output, x); |
| s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128); |
| for(i=0; i<128; i++) |
| x[i] = s->transform_coeffs[ch][2*i+1]; |
| ff_imdct_half(&s->imdct_256, s->delay[ch-1], x); |
| } else { |
| ff_imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]); |
| s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, add_bias, 128); |
| memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float)); |
| } |
| } |
| } |
| |
| /** |
| * Downmix the output to mono or stereo. |
| */ |
| void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len) |
| { |
| int i, j; |
| float v0, v1; |
| if(out_ch == 2) { |
| for(i=0; i<len; i++) { |
| v0 = v1 = 0.0f; |
| for(j=0; j<in_ch; j++) { |
| v0 += samples[j][i] * matrix[j][0]; |
| v1 += samples[j][i] * matrix[j][1]; |
| } |
| samples[0][i] = v0; |
| samples[1][i] = v1; |
| } |
| } else if(out_ch == 1) { |
| for(i=0; i<len; i++) { |
| v0 = 0.0f; |
| for(j=0; j<in_ch; j++) |
| v0 += samples[j][i] * matrix[j][0]; |
| samples[0][i] = v0; |
| } |
| } |
| } |
| |
| /** |
| * Upmix delay samples from stereo to original channel layout. |
| */ |
| static void ac3_upmix_delay(AC3DecodeContext *s) |
| { |
| int channel_data_size = sizeof(s->delay[0]); |
| switch(s->channel_mode) { |
| case AC3_CHMODE_DUALMONO: |
| case AC3_CHMODE_STEREO: |
| /* upmix mono to stereo */ |
| memcpy(s->delay[1], s->delay[0], channel_data_size); |
| break; |
| case AC3_CHMODE_2F2R: |
| memset(s->delay[3], 0, channel_data_size); |
| case AC3_CHMODE_2F1R: |
| memset(s->delay[2], 0, channel_data_size); |
| break; |
| case AC3_CHMODE_3F2R: |
| memset(s->delay[4], 0, channel_data_size); |
| case AC3_CHMODE_3F1R: |
| memset(s->delay[3], 0, channel_data_size); |
| case AC3_CHMODE_3F: |
| memcpy(s->delay[2], s->delay[1], channel_data_size); |
| memset(s->delay[1], 0, channel_data_size); |
| break; |
| } |
| } |
| |
| /** |
| * Decode band structure for coupling, spectral extension, or enhanced coupling. |
| * @param[in] gbc bit reader context |
| * @param[in] blk block number |
| * @param[in] eac3 flag to indicate E-AC-3 |
| * @param[in] ecpl flag to indicate enhanced coupling |
| * @param[in] start_subband subband number for start of range |
| * @param[in] end_subband subband number for end of range |
| * @param[in] default_band_struct default band structure table |
| * @param[out] band_struct decoded band structure |
| * @param[out] num_subbands number of subbands (optionally NULL) |
| * @param[out] num_bands number of bands (optionally NULL) |
| * @param[out] band_sizes array containing the number of bins in each band (optionally NULL) |
| */ |
| static void decode_band_structure(GetBitContext *gbc, int blk, int eac3, |
| int ecpl, int start_subband, int end_subband, |
| const uint8_t *default_band_struct, |
| uint8_t *band_struct, int *num_subbands, |
| int *num_bands, uint8_t *band_sizes) |
| { |
| int subbnd, bnd, n_subbands, n_bands=0; |
| uint8_t bnd_sz[22]; |
| |
| n_subbands = end_subband - start_subband; |
| |
| /* decode band structure from bitstream or use default */ |
| if (!eac3 || get_bits1(gbc)) { |
| for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) { |
| band_struct[subbnd] = get_bits1(gbc); |
| } |
| } else if (!blk) { |
| memcpy(band_struct, |
| &default_band_struct[start_subband+1], |
| n_subbands-1); |
| } |
| band_struct[n_subbands-1] = 0; |
| |
| /* calculate number of bands and band sizes based on band structure. |
| note that the first 4 subbands in enhanced coupling span only 6 bins |
| instead of 12. */ |
| if (num_bands || band_sizes ) { |
| n_bands = n_subbands; |
| bnd_sz[0] = ecpl ? 6 : 12; |
| for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) { |
| int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12; |
| if (band_struct[subbnd-1]) { |
| n_bands--; |
| bnd_sz[bnd] += subbnd_size; |
| } else { |
| bnd_sz[++bnd] = subbnd_size; |
| } |
| } |
| } |
| |
| /* set optional output params */ |
| if (num_subbands) |
| *num_subbands = n_subbands; |
| if (num_bands) |
| *num_bands = n_bands; |
| if (band_sizes) |
| memcpy(band_sizes, bnd_sz, n_bands); |
| } |
| |
| /** |
| * Decode a single audio block from the AC-3 bitstream. |
| */ |
| static int decode_audio_block(AC3DecodeContext *s, int blk) |
| { |
| int fbw_channels = s->fbw_channels; |
| int channel_mode = s->channel_mode; |
| int i, bnd, seg, ch; |
| int different_transforms; |
| int downmix_output; |
| int cpl_in_use; |
| GetBitContext *gbc = &s->gbc; |
| uint8_t bit_alloc_stages[AC3_MAX_CHANNELS]; |
| |
| memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS); |
| |
| /* block switch flags */ |
| different_transforms = 0; |
| if (s->block_switch_syntax) { |
| for (ch = 1; ch <= fbw_channels; ch++) { |
| s->block_switch[ch] = get_bits1(gbc); |
| if(ch > 1 && s->block_switch[ch] != s->block_switch[1]) |
| different_transforms = 1; |
| } |
| } |
| |
| /* dithering flags */ |
| if (s->dither_flag_syntax) { |
| for (ch = 1; ch <= fbw_channels; ch++) { |
| s->dither_flag[ch] = get_bits1(gbc); |
| } |
| } |
| |
| /* dynamic range */ |
| i = !(s->channel_mode); |
| do { |
| if(get_bits1(gbc)) { |
| s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) * |
| s->avctx->drc_scale)+1.0; |
| } else if(blk == 0) { |
| s->dynamic_range[i] = 1.0f; |
| } |
| } while(i--); |
| |
| /* spectral extension strategy */ |
| if (s->eac3 && (!blk || get_bits1(gbc))) { |
| if (get_bits1(gbc)) { |
| ff_log_missing_feature(s->avctx, "Spectral extension", 1); |
| return -1; |
| } |
| /* TODO: parse spectral extension strategy info */ |
| } |
| |
| /* TODO: spectral extension coordinates */ |
| |
| /* coupling strategy */ |
| if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) { |
| memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); |
| if (!s->eac3) |
| s->cpl_in_use[blk] = get_bits1(gbc); |
| if (s->cpl_in_use[blk]) { |
| /* coupling in use */ |
| int cpl_start_subband, cpl_end_subband; |
| |
| if (channel_mode < AC3_CHMODE_STEREO) { |
| av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n"); |
| return -1; |
| } |
| |
| /* check for enhanced coupling */ |
| if (s->eac3 && get_bits1(gbc)) { |
| /* TODO: parse enhanced coupling strategy info */ |
| ff_log_missing_feature(s->avctx, "Enhanced coupling", 1); |
| return -1; |
| } |
| |
| /* determine which channels are coupled */ |
| if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) { |
| s->channel_in_cpl[1] = 1; |
| s->channel_in_cpl[2] = 1; |
| } else { |
| for (ch = 1; ch <= fbw_channels; ch++) |
| s->channel_in_cpl[ch] = get_bits1(gbc); |
| } |
| |
| /* phase flags in use */ |
| if (channel_mode == AC3_CHMODE_STEREO) |
| s->phase_flags_in_use = get_bits1(gbc); |
| |
| /* coupling frequency range */ |
| /* TODO: modify coupling end freq if spectral extension is used */ |
| cpl_start_subband = get_bits(gbc, 4); |
| cpl_end_subband = get_bits(gbc, 4) + 3; |
| s->num_cpl_subbands = cpl_end_subband - cpl_start_subband; |
| if (s->num_cpl_subbands < 0) { |
| av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d > %d)\n", |
| cpl_start_subband, cpl_end_subband); |
| return -1; |
| } |
| s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37; |
| s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37; |
| |
| decode_band_structure(gbc, blk, s->eac3, 0, |
| cpl_start_subband, cpl_end_subband, |
| ff_eac3_default_cpl_band_struct, |
| s->cpl_band_struct, &s->num_cpl_subbands, |
| &s->num_cpl_bands, NULL); |
| } else { |
| /* coupling not in use */ |
| for (ch = 1; ch <= fbw_channels; ch++) { |
| s->channel_in_cpl[ch] = 0; |
| s->first_cpl_coords[ch] = 1; |
| } |
| s->first_cpl_leak = s->eac3; |
| s->phase_flags_in_use = 0; |
| } |
| } else if (!s->eac3) { |
| if(!blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n"); |
| return -1; |
| } else { |
| s->cpl_in_use[blk] = s->cpl_in_use[blk-1]; |
| } |
| } |
| cpl_in_use = s->cpl_in_use[blk]; |
| |
| /* coupling coordinates */ |
| if (cpl_in_use) { |
| int cpl_coords_exist = 0; |
| |
| for (ch = 1; ch <= fbw_channels; ch++) { |
| if (s->channel_in_cpl[ch]) { |
| if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) { |
| int master_cpl_coord, cpl_coord_exp, cpl_coord_mant; |
| s->first_cpl_coords[ch] = 0; |
| cpl_coords_exist = 1; |
| master_cpl_coord = 3 * get_bits(gbc, 2); |
| for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { |
| cpl_coord_exp = get_bits(gbc, 4); |
| cpl_coord_mant = get_bits(gbc, 4); |
| if (cpl_coord_exp == 15) |
| s->cpl_coords[ch][bnd] = cpl_coord_mant << 22; |
| else |
| s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21; |
| s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord); |
| } |
| } else if (!blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n"); |
| return -1; |
| } |
| } else { |
| /* channel not in coupling */ |
| s->first_cpl_coords[ch] = 1; |
| } |
| } |
| /* phase flags */ |
| if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) { |
| for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { |
| s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0; |
| } |
| } |
| } |
| |
| /* stereo rematrixing strategy and band structure */ |
| if (channel_mode == AC3_CHMODE_STEREO) { |
| if ((s->eac3 && !blk) || get_bits1(gbc)) { |
| s->num_rematrixing_bands = 4; |
| if(cpl_in_use && s->start_freq[CPL_CH] <= 61) |
| s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37); |
| for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) |
| s->rematrixing_flags[bnd] = get_bits1(gbc); |
| } else if (!blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new rematrixing strategy must be present in block 0\n"); |
| return -1; |
| } |
| } |
| |
| /* exponent strategies for each channel */ |
| for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
| if (!s->eac3) |
| s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch)); |
| if(s->exp_strategy[blk][ch] != EXP_REUSE) |
| bit_alloc_stages[ch] = 3; |
| } |
| |
| /* channel bandwidth */ |
| for (ch = 1; ch <= fbw_channels; ch++) { |
| s->start_freq[ch] = 0; |
| if (s->exp_strategy[blk][ch] != EXP_REUSE) { |
| int group_size; |
| int prev = s->end_freq[ch]; |
| if (s->channel_in_cpl[ch]) |
| s->end_freq[ch] = s->start_freq[CPL_CH]; |
| else { |
| int bandwidth_code = get_bits(gbc, 6); |
| if (bandwidth_code > 60) { |
| av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code); |
| return -1; |
| } |
| s->end_freq[ch] = bandwidth_code * 3 + 73; |
| } |
| group_size = 3 << (s->exp_strategy[blk][ch] - 1); |
| s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size; |
| if(blk > 0 && s->end_freq[ch] != prev) |
| memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); |
| } |
| } |
| if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) { |
| s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) / |
| (3 << (s->exp_strategy[blk][CPL_CH] - 1)); |
| } |
| |
| /* decode exponents for each channel */ |
| for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
| if (s->exp_strategy[blk][ch] != EXP_REUSE) { |
| s->dexps[ch][0] = get_bits(gbc, 4) << !ch; |
| if (decode_exponents(gbc, s->exp_strategy[blk][ch], |
| s->num_exp_groups[ch], s->dexps[ch][0], |
| &s->dexps[ch][s->start_freq[ch]+!!ch])) { |
| av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n"); |
| return -1; |
| } |
| if(ch != CPL_CH && ch != s->lfe_ch) |
| skip_bits(gbc, 2); /* skip gainrng */ |
| } |
| } |
| |
| /* bit allocation information */ |
| if (s->bit_allocation_syntax) { |
| if (get_bits1(gbc)) { |
| s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; |
| s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; |
| s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)]; |
| s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)]; |
| s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)]; |
| for(ch=!cpl_in_use; ch<=s->channels; ch++) |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
| } else if (!blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n"); |
| return -1; |
| } |
| } |
| |
| /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */ |
| if(!s->eac3 || !blk){ |
| if(s->snr_offset_strategy && get_bits1(gbc)) { |
| int snr = 0; |
| int csnr; |
| csnr = (get_bits(gbc, 6) - 15) << 4; |
| for (i = ch = !cpl_in_use; ch <= s->channels; ch++) { |
| /* snr offset */ |
| if (ch == i || s->snr_offset_strategy == 2) |
| snr = (csnr + get_bits(gbc, 4)) << 2; |
| /* run at least last bit allocation stage if snr offset changes */ |
| if(blk && s->snr_offset[ch] != snr) { |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1); |
| } |
| s->snr_offset[ch] = snr; |
| |
| /* fast gain (normal AC-3 only) */ |
| if (!s->eac3) { |
| int prev = s->fast_gain[ch]; |
| s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; |
| /* run last 2 bit allocation stages if fast gain changes */ |
| if(blk && prev != s->fast_gain[ch]) |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
| } |
| } |
| } else if (!s->eac3 && !blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n"); |
| return -1; |
| } |
| } |
| |
| /* fast gain (E-AC-3 only) */ |
| if (s->fast_gain_syntax && get_bits1(gbc)) { |
| for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
| int prev = s->fast_gain[ch]; |
| s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; |
| /* run last 2 bit allocation stages if fast gain changes */ |
| if(blk && prev != s->fast_gain[ch]) |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
| } |
| } else if (s->eac3 && !blk) { |
| for (ch = !cpl_in_use; ch <= s->channels; ch++) |
| s->fast_gain[ch] = ff_ac3_fast_gain_tab[4]; |
| } |
| |
| /* E-AC-3 to AC-3 converter SNR offset */ |
| if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) { |
| skip_bits(gbc, 10); // skip converter snr offset |
| } |
| |
| /* coupling leak information */ |
| if (cpl_in_use) { |
| if (s->first_cpl_leak || get_bits1(gbc)) { |
| int fl = get_bits(gbc, 3); |
| int sl = get_bits(gbc, 3); |
| /* run last 2 bit allocation stages for coupling channel if |
| coupling leak changes */ |
| if(blk && (fl != s->bit_alloc_params.cpl_fast_leak || |
| sl != s->bit_alloc_params.cpl_slow_leak)) { |
| bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2); |
| } |
| s->bit_alloc_params.cpl_fast_leak = fl; |
| s->bit_alloc_params.cpl_slow_leak = sl; |
| } else if (!s->eac3 && !blk) { |
| av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n"); |
| return -1; |
| } |
| s->first_cpl_leak = 0; |
| } |
| |
| /* delta bit allocation information */ |
| if (s->dba_syntax && get_bits1(gbc)) { |
| /* delta bit allocation exists (strategy) */ |
| for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { |
| s->dba_mode[ch] = get_bits(gbc, 2); |
| if (s->dba_mode[ch] == DBA_RESERVED) { |
| av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n"); |
| return -1; |
| } |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
| } |
| /* channel delta offset, len and bit allocation */ |
| for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { |
| if (s->dba_mode[ch] == DBA_NEW) { |
| s->dba_nsegs[ch] = get_bits(gbc, 3); |
| for (seg = 0; seg <= s->dba_nsegs[ch]; seg++) { |
| s->dba_offsets[ch][seg] = get_bits(gbc, 5); |
| s->dba_lengths[ch][seg] = get_bits(gbc, 4); |
| s->dba_values[ch][seg] = get_bits(gbc, 3); |
| } |
| /* run last 2 bit allocation stages if new dba values */ |
| bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
| } |
| } |
| } else if(blk == 0) { |
| for(ch=0; ch<=s->channels; ch++) { |
| s->dba_mode[ch] = DBA_NONE; |
| } |
| } |
| |
| /* Bit allocation */ |
| for(ch=!cpl_in_use; ch<=s->channels; ch++) { |
| if(bit_alloc_stages[ch] > 2) { |
| /* Exponent mapping into PSD and PSD integration */ |
| ff_ac3_bit_alloc_calc_psd(s->dexps[ch], |
| s->start_freq[ch], s->end_freq[ch], |
| s->psd[ch], s->band_psd[ch]); |
| } |
| if(bit_alloc_stages[ch] > 1) { |
| /* Compute excitation function, Compute masking curve, and |
| Apply delta bit allocation */ |
| if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch], |
| s->start_freq[ch], s->end_freq[ch], |
| s->fast_gain[ch], (ch == s->lfe_ch), |
| s->dba_mode[ch], s->dba_nsegs[ch], |
| s->dba_offsets[ch], s->dba_lengths[ch], |
| s->dba_values[ch], s->mask[ch])) { |
| av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n"); |
| return -1; |
| } |
| } |
| if(bit_alloc_stages[ch] > 0) { |
| /* Compute bit allocation */ |
| const uint8_t *bap_tab = s->channel_uses_aht[ch] ? |
| ff_eac3_hebap_tab : ff_ac3_bap_tab; |
| ff_ac3_bit_alloc_calc_bap(s->mask[ch], s->psd[ch], |
| s->start_freq[ch], s->end_freq[ch], |
| s->snr_offset[ch], |
| s->bit_alloc_params.floor, |
| bap_tab, s->bap[ch]); |
| } |
| } |
| |
| /* unused dummy data */ |
| if (s->skip_syntax && get_bits1(gbc)) { |
| int skipl = get_bits(gbc, 9); |
| while(skipl--) |
| skip_bits(gbc, 8); |
| } |
| |
| /* unpack the transform coefficients |
| this also uncouples channels if coupling is in use. */ |
| decode_transform_coeffs(s, blk); |
| |
| /* TODO: generate enhanced coupling coordinates and uncouple */ |
| |
| /* TODO: apply spectral extension */ |
| |
| /* recover coefficients if rematrixing is in use */ |
| if(s->channel_mode == AC3_CHMODE_STEREO) |
| do_rematrixing(s); |
| |
| /* apply scaling to coefficients (headroom, dynrng) */ |
| for(ch=1; ch<=s->channels; ch++) { |
| float gain = s->mul_bias / 4194304.0f; |
| if(s->channel_mode == AC3_CHMODE_DUALMONO) { |
| gain *= s->dynamic_range[ch-1]; |
| } else { |
| gain *= s->dynamic_range[0]; |
| } |
| s->dsp.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256); |
| } |
| |
| /* downmix and MDCT. order depends on whether block switching is used for |
| any channel in this block. this is because coefficients for the long |
| and short transforms cannot be mixed. */ |
| downmix_output = s->channels != s->out_channels && |
| !((s->output_mode & AC3_OUTPUT_LFEON) && |
| s->fbw_channels == s->out_channels); |
| if(different_transforms) { |
| /* the delay samples have already been downmixed, so we upmix the delay |
| samples in order to reconstruct all channels before downmixing. */ |
| if(s->downmixed) { |
| s->downmixed = 0; |
| ac3_upmix_delay(s); |
| } |
| |
| do_imdct(s, s->channels); |
| |
| if(downmix_output) { |
| s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); |
| } |
| } else { |
| if(downmix_output) { |
| s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); |
| } |
| |
| if(downmix_output && !s->downmixed) { |
| s->downmixed = 1; |
| s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128); |
| } |
| |
| do_imdct(s, s->out_channels); |
| } |
| |
| return 0; |
| } |
| |
| /** |
| * Decode a single AC-3 frame. |
| */ |
| static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, |
| const uint8_t *buf, int buf_size) |
| { |
| AC3DecodeContext *s = avctx->priv_data; |
| int16_t *out_samples = (int16_t *)data; |
| int blk, ch, err; |
| |
| /* initialize the GetBitContext with the start of valid AC-3 Frame */ |
| if (s->input_buffer) { |
| /* copy input buffer to decoder context to avoid reading past the end |
| of the buffer, which can be caused by a damaged input stream. */ |
| memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE)); |
| init_get_bits(&s->gbc, s->input_buffer, buf_size * 8); |
| } else { |
| init_get_bits(&s->gbc, buf, buf_size * 8); |
| } |
| |
| /* parse the syncinfo */ |
| *data_size = 0; |
| err = parse_frame_header(s); |
| |
| /* check that reported frame size fits in input buffer */ |
| if(s->frame_size > buf_size) { |
| av_log(avctx, AV_LOG_ERROR, "incomplete frame\n"); |
| err = AAC_AC3_PARSE_ERROR_FRAME_SIZE; |
| } |
| |
| /* check for crc mismatch */ |
| if(err != AAC_AC3_PARSE_ERROR_FRAME_SIZE && avctx->error_recognition >= FF_ER_CAREFUL) { |
| if(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) { |
| av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n"); |
| err = AAC_AC3_PARSE_ERROR_CRC; |
| } |
| } |
| |
| if(err && err != AAC_AC3_PARSE_ERROR_CRC) { |
| switch(err) { |
| case AAC_AC3_PARSE_ERROR_SYNC: |
| av_log(avctx, AV_LOG_ERROR, "frame sync error\n"); |
| return -1; |
| case AAC_AC3_PARSE_ERROR_BSID: |
| av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n"); |
| break; |
| case AAC_AC3_PARSE_ERROR_SAMPLE_RATE: |
| av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n"); |
| break; |
| case AAC_AC3_PARSE_ERROR_FRAME_SIZE: |
| av_log(avctx, AV_LOG_ERROR, "invalid frame size\n"); |
| break; |
| case AAC_AC3_PARSE_ERROR_FRAME_TYPE: |
| /* skip frame if CRC is ok. otherwise use error concealment. */ |
| /* TODO: add support for substreams and dependent frames */ |
| if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) { |
| av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n"); |
| return s->frame_size; |
| } else { |
| av_log(avctx, AV_LOG_ERROR, "invalid frame type\n"); |
| } |
| break; |
| default: |
| av_log(avctx, AV_LOG_ERROR, "invalid header\n"); |
| break; |
| } |
| } |
| |
| /* if frame is ok, set audio parameters */ |
| if (!err) { |
| avctx->sample_rate = s->sample_rate; |
| avctx->bit_rate = s->bit_rate; |
| |
| /* channel config */ |
| s->out_channels = s->channels; |
| s->output_mode = s->channel_mode; |
| if(s->lfe_on) |
| s->output_mode |= AC3_OUTPUT_LFEON; |
| if (avctx->request_channels > 0 && avctx->request_channels <= 2 && |
| avctx->request_channels < s->channels) { |
| s->out_channels = avctx->request_channels; |
| s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO; |
| } |
| avctx->channels = s->out_channels; |
| |
| /* set downmixing coefficients if needed */ |
| if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) && |
| s->fbw_channels == s->out_channels)) { |
| set_downmix_coeffs(s); |
| } |
| } else if (!s->out_channels) { |
| s->out_channels = avctx->channels; |
| if(s->out_channels < s->channels) |
| s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO; |
| } |
| |
| /* decode the audio blocks */ |
| for (blk = 0; blk < s->num_blocks; blk++) { |
| const float *output[s->out_channels]; |
| if (!err && decode_audio_block(s, blk)) { |
| av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n"); |
| err = 1; |
| } |
| for (ch = 0; ch < s->out_channels; ch++) |
| output[ch] = s->output[ch]; |
| s->dsp.float_to_int16_interleave(out_samples, output, 256, s->out_channels); |
| out_samples += 256 * s->out_channels; |
| } |
| *data_size = s->num_blocks * 256 * avctx->channels * sizeof (int16_t); |
| return s->frame_size; |
| } |
| |
| /** |
| * Uninitialize the AC-3 decoder. |
| */ |
| static av_cold int ac3_decode_end(AVCodecContext *avctx) |
| { |
| AC3DecodeContext *s = avctx->priv_data; |
| ff_mdct_end(&s->imdct_512); |
| ff_mdct_end(&s->imdct_256); |
| |
| av_freep(&s->input_buffer); |
| |
| return 0; |
| } |
| |
| AVCodec ac3_decoder = { |
| .name = "ac3", |
| .type = CODEC_TYPE_AUDIO, |
| .id = CODEC_ID_AC3, |
| .priv_data_size = sizeof (AC3DecodeContext), |
| .init = ac3_decode_init, |
| .close = ac3_decode_end, |
| .decode = ac3_decode_frame, |
| .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), |
| }; |
| |
| AVCodec eac3_decoder = { |
| .name = "eac3", |
| .type = CODEC_TYPE_AUDIO, |
| .id = CODEC_ID_EAC3, |
| .priv_data_size = sizeof (AC3DecodeContext), |
| .init = ac3_decode_init, |
| .close = ac3_decode_end, |
| .decode = ac3_decode_frame, |
| .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"), |
| }; |
