/* * 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 Libav. * * Libav 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. * * Libav 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 Libav; 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/channel_layout.h" #include "libavutil/crc.h" #include "libavutil/downmix_info.h" #include "libavutil/opt.h" #include "bswapdsp.h" #include "internal.h" #include "aac_ac3_parser.h" #include "ac3_parser.h" #include "ac3dec.h" #include "ac3dec_data.h" #include "kbdwin.h" /** * 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 */ 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 }; /** Adjustments in dB gain (LFE, +10 to -21 dB) */ static const float gain_levels_lfe[32] = { 3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893, 1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946, 0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227, 0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253, 0.125892, 0.112201, 0.100000, 0.089125 }; /** * 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; int i; s->avctx = avctx; ff_ac3_common_init(); ac3_tables_init(); ff_mdct_init(&s->imdct_256, 8, 1, 1.0); ff_mdct_init(&s->imdct_512, 9, 1, 1.0); ff_kbd_window_init(s->window, 5.0, 256); ff_bswapdsp_init(&s->bdsp); avpriv_float_dsp_init(&s->fdsp, avctx->flags & CODEC_FLAG_BITEXACT); ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT); ff_fmt_convert_init(&s->fmt_conv, avctx); av_lfg_init(&s->dith_state, 0); avctx->sample_fmt = AV_SAMPLE_FMT_FLTP; /* allow downmixing to stereo or mono */ #if FF_API_REQUEST_CHANNELS FF_DISABLE_DEPRECATION_WARNINGS if (avctx->request_channels == 1) avctx->request_channel_layout = AV_CH_LAYOUT_MONO; else if (avctx->request_channels == 2) avctx->request_channel_layout = AV_CH_LAYOUT_STEREO; FF_ENABLE_DEPRECATION_WARNINGS #endif if (avctx->channels > 1 && avctx->request_channel_layout == AV_CH_LAYOUT_MONO) avctx->channels = 1; else if (avctx->channels > 2 && avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) avctx->channels = 2; s->downmixed = 1; for (i = 0; i < AC3_MAX_CHANNELS; i++) { s->xcfptr[i] = s->transform_coeffs[i]; s->dlyptr[i] = s->delay[i]; } 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 parse the Alternate Bit Stream Syntax */ if (s->bitstream_id != 6) { if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode1 if (get_bits1(gbc)) skip_bits(gbc, 14); //skip timecode2 } else { if (get_bits1(gbc)) { s->preferred_downmix = get_bits(gbc, 2); s->center_mix_level_ltrt = get_bits(gbc, 3); s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7); s->center_mix_level = get_bits(gbc, 3); s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7); } if (get_bits1(gbc)) { s->dolby_surround_ex_mode = get_bits(gbc, 2); s->dolby_headphone_mode = get_bits(gbc, 2); skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1) } } /* 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 = avpriv_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->bitstream_id = hdr.bitstream_id; s->bitstream_mode = hdr.bitstream_mode; 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->preferred_downmix = AC3_DMIXMOD_NOTINDICATED; s->center_mix_level = hdr.center_mix_level; s->center_mix_level_ltrt = 4; // -3.0dB s->surround_mix_level = hdr.surround_mix_level; s->surround_mix_level_ltrt = 4; // -3.0dB s->lfe_mix_level_exists = 0; s->num_blocks = hdr.num_blocks; s->frame_type = hdr.frame_type; s->substreamid = hdr.substreamid; s->dolby_surround_mode = hdr.dolby_surround_mode; s->dolby_surround_ex_mode = AC3_DSUREXMOD_NOTINDICATED; s->dolby_headphone_mode = AC3_DHEADPHONMOD_NOTINDICATED; 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 (s->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 if (CONFIG_EAC3_DECODER) { s->eac3 = 1; return ff_eac3_parse_header(s); } else { av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n"); return AVERROR(ENOSYS); } } /** * 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[s-> center_mix_level]; float smix = gain_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 bin, band, ch; bin = s->start_freq[CPL_CH]; for (band = 0; band < s->num_cpl_bands; band++) { int band_start = bin; int band_end = bin + s->cpl_band_sizes[band]; for (ch = 1; ch <= s->fbw_channels; ch++) { if (s->channel_in_cpl[ch]) { int cpl_coord = s->cpl_coords[ch][band] << 5; for (bin = band_start; bin < band_end; bin++) { s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord); } if (ch == 2 && s->phase_flags[band]) { for (bin = band_start; bin < band_end; bin++) s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin]; } } } bin = band_end; } } /** * 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]; int32_t *coeffs = s->fixed_coeffs[ch_index]; int dither = (ch_index == CPL_CH) || s->dither_flag[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: /* random noise with approximate range of -0.707 to 0.707 */ if (dither) mantissa = (av_lfg_get(&s->dith_state) / 362) - 5932275; else mantissa = 0; 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 */ /* Shift mantissa and sign-extend it. */ mantissa = get_sbits(gbc, quantization_tab[bap]); mantissa <<= 24 - quantization_tab[bap]; break; } coeffs[freq] = mantissa >> exps[freq]; } } /** * Remove random dithering from coupling range coefficients with zero-bit * mantissas for coupled channels which do not use dithering. * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0) */ static void remove_dithering(AC3DecodeContext *s) { int ch, i; for (ch = 1; ch <= s->fbw_channels; ch++) { if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) { for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) { if (!s->bap[CPL_CH][i]) s->fixed_coeffs[ch][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 && CONFIG_EAC3_DECODER) 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); /* transform 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; 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++) { int tmp0 = s->fixed_coeffs[1][i]; s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i]; s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i]; } } } } /** * 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; 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]; s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x); s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1], s->tmp_output, s->window, 128); for (i = 0; i < 128; i++) x[i] = s->transform_coeffs[ch][2 * i + 1]; s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x); } else { s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]); s->fdsp.vector_fmul_window(s->outptr[ch - 1], s->delay[ch - 1], s->tmp_output, s->window, 128); memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float)); } } } /** * 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. * The band structure defines how many subbands are in each band. For each * subband in the range, 1 means it is combined with the previous band, and 0 * means that it starts a new band. * * @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] 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, int *num_bands, uint8_t *band_sizes) { int subbnd, bnd, n_subbands, n_bands=0; uint8_t bnd_sz[22]; uint8_t coded_band_struct[22]; const uint8_t *band_struct; 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++) { coded_band_struct[subbnd] = get_bits1(gbc); } band_struct = coded_band_struct; } else if (!blk) { band_struct = &default_band_struct[start_subband+1]; } else { /* no change in band structure */ return; } /* 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_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] = { 0 }; /* 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)) { /* Allow asymmetric application of DRC when drc_scale > 1. Amplification of quiet sounds is enhanced */ float range = dynamic_range_tab[get_bits(gbc, 8)]; if (range > 1.0 || s->drc_scale <= 1.0) s->dynamic_range[i] = powf(range, s->drc_scale); else s->dynamic_range[i] = range; } else if (blk == 0) { s->dynamic_range[i] = 1.0f; } } while (i--); /* spectral extension strategy */ if (s->eac3 && (!blk || get_bits1(gbc))) { s->spx_in_use = get_bits1(gbc); if (s->spx_in_use) { int dst_start_freq, dst_end_freq, src_start_freq, start_subband, end_subband; /* determine which channels use spx */ if (s->channel_mode == AC3_CHMODE_MONO) { s->channel_uses_spx[1] = 1; } else { for (ch = 1; ch <= fbw_channels; ch++) s->channel_uses_spx[ch] = get_bits1(gbc); } /* get the frequency bins of the spx copy region and the spx start and end subbands */ dst_start_freq = get_bits(gbc, 2); start_subband = get_bits(gbc, 3) + 2; if (start_subband > 7) start_subband += start_subband - 7; end_subband = get_bits(gbc, 3) + 5; if (end_subband > 7) end_subband += end_subband - 7; dst_start_freq = dst_start_freq * 12 + 25; src_start_freq = start_subband * 12 + 25; dst_end_freq = end_subband * 12 + 25; /* check validity of spx ranges */ if (start_subband >= end_subband) { av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " "range (%d >= %d)\n", start_subband, end_subband); return AVERROR_INVALIDDATA; } if (dst_start_freq >= src_start_freq) { av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq); return AVERROR_INVALIDDATA; } s->spx_dst_start_freq = dst_start_freq; s->spx_src_start_freq = src_start_freq; s->spx_dst_end_freq = dst_end_freq; decode_band_structure(gbc, blk, s->eac3, 0, start_subband, end_subband, ff_eac3_default_spx_band_struct, &s->num_spx_bands, s->spx_band_sizes); } else { for (ch = 1; ch <= fbw_channels; ch++) { s->channel_uses_spx[ch] = 0; s->first_spx_coords[ch] = 1; } } } /* spectral extension coordinates */ if (s->spx_in_use) { for (ch = 1; ch <= fbw_channels; ch++) { if (s->channel_uses_spx[ch]) { if (s->first_spx_coords[ch] || get_bits1(gbc)) { float spx_blend; int bin, master_spx_coord; s->first_spx_coords[ch] = 0; spx_blend = get_bits(gbc, 5) * (1.0f/32); master_spx_coord = get_bits(gbc, 2) * 3; bin = s->spx_src_start_freq; for (bnd = 0; bnd < s->num_spx_bands; bnd++) { int bandsize; int spx_coord_exp, spx_coord_mant; float nratio, sblend, nblend, spx_coord; /* calculate blending factors */ bandsize = s->spx_band_sizes[bnd]; nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend; nratio = av_clipf(nratio, 0.0f, 1.0f); nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) // to give unity variance sblend = sqrtf(1.0f - nratio); bin += bandsize; /* decode spx coordinates */ spx_coord_exp = get_bits(gbc, 4); spx_coord_mant = get_bits(gbc, 2); if (spx_coord_exp == 15) spx_coord_mant <<= 1; else spx_coord_mant += 4; spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord); spx_coord = spx_coord_mant * (1.0f / (1 << 23)); /* multiply noise and signal blending factors by spx coordinate */ s->spx_noise_blend [ch][bnd] = nblend * spx_coord; s->spx_signal_blend[ch][bnd] = sblend * spx_coord; } } } else { s->first_spx_coords[ch] = 1; } } } /* 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 AVERROR_INVALIDDATA; } /* check for enhanced coupling */ if (s->eac3 && get_bits1(gbc)) { /* TODO: parse enhanced coupling strategy info */ avpriv_request_sample(s->avctx, "Enhanced coupling"); return AVERROR_PATCHWELCOME; } /* 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 */ cpl_start_subband = get_bits(gbc, 4); cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 : get_bits(gbc, 4) + 3; if (cpl_start_subband >= cpl_end_subband) { av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n", cpl_start_subband, cpl_end_subband); return AVERROR_INVALIDDATA; } 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->num_cpl_bands, s->cpl_band_sizes); } 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 AVERROR_INVALIDDATA; } 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 AVERROR_INVALIDDATA; } } 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); } else if (s->spx_in_use && s->spx_src_start_freq <= 61) { s->num_rematrixing_bands--; } 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_WARNING, "Warning: " "new rematrixing strategy not present in block 0\n"); s->num_rematrixing_bands = 0; } } /* 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 if (s->channel_uses_spx[ch]) s->end_freq[ch] = s->spx_src_start_freq; 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 AVERROR_INVALIDDATA; } 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 AVERROR_INVALIDDATA; } 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 AVERROR_INVALIDDATA; } } /* 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 AVERROR_INVALIDDATA; } } /* 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 AVERROR_INVALIDDATA; } 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 AVERROR_INVALIDDATA; } 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) + 1; 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 AVERROR_INVALIDDATA; } } 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; s->ac3dsp.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 */ /* 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 = 1.0 / 4194304.0f; if (s->channel_mode == AC3_CHMODE_DUALMONO) { gain *= s->dynamic_range[2 - ch]; } else { gain *= s->dynamic_range[0]; } s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256); } /* apply spectral extension to high frequency bins */ if (s->spx_in_use && CONFIG_EAC3_DECODER) { ff_eac3_apply_spectral_extension(s); } /* 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->ac3dsp.downmix(s->outptr, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); } } else { if (downmix_output) { s->ac3dsp.downmix(s->xcfptr + 1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256); } if (downmix_output && !s->downmixed) { s->downmixed = 1; s->ac3dsp.downmix(s->dlyptr, 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 *got_frame_ptr, AVPacket *avpkt) { AVFrame *frame = data; const uint8_t *buf = avpkt->data; int buf_size = avpkt->size; AC3DecodeContext *s = avctx->priv_data; int blk, ch, err, ret; const uint8_t *channel_map; const float *output[AC3_MAX_CHANNELS]; enum AVMatrixEncoding matrix_encoding; AVDownmixInfo *downmix_info; /* copy input buffer to decoder context to avoid reading past the end of the buffer, which can be caused by a damaged input stream. */ if (buf_size >= 2 && AV_RB16(buf) == 0x770B) { // seems to be byte-swapped AC-3 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1; s->bdsp.bswap16_buf((uint16_t *) s->input_buffer, (const uint16_t *) buf, cnt); } else memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE)); buf = s->input_buffer; /* initialize the GetBitContext with the start of valid AC-3 Frame */ init_get_bits(&s->gbc, buf, buf_size * 8); /* parse the syncinfo */ err = parse_frame_header(s); if (err) { switch (err) { case AAC_AC3_PARSE_ERROR_SYNC: av_log(avctx, AV_LOG_ERROR, "frame sync error\n"); return AVERROR_INVALIDDATA; 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_WARNING, "unsupported frame type : " "skipping frame\n"); *got_frame_ptr = 0; return buf_size; } else { av_log(avctx, AV_LOG_ERROR, "invalid frame type\n"); } break; case AAC_AC3_PARSE_ERROR_CRC: case AAC_AC3_PARSE_ERROR_CHANNEL_CFG: break; default: // Normal AVERROR do not try to recover. *got_frame_ptr = 0; return err; } } else { /* 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; } else if (avctx->err_recognition & AV_EF_CRCCHECK) { /* check for crc mismatch */ 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"); if (avctx->err_recognition & AV_EF_EXPLODE) return AVERROR_INVALIDDATA; err = AAC_AC3_PARSE_ERROR_CRC; } } } /* if frame is ok, set audio parameters */ if (!err) { avctx->sample_rate = s->sample_rate; avctx->bit_rate = s->bit_rate; } /* channel config */ if (!err || (s->channels && s->out_channels != s->channels)) { s->out_channels = s->channels; s->output_mode = s->channel_mode; if (s->lfe_on) s->output_mode |= AC3_OUTPUT_LFEON; if (s->channels > 1 && avctx->request_channel_layout == AV_CH_LAYOUT_MONO) { s->out_channels = 1; s->output_mode = AC3_CHMODE_MONO; } else if (s->channels > 2 && avctx->request_channel_layout == AV_CH_LAYOUT_STEREO) { s->out_channels = 2; s->output_mode = AC3_CHMODE_STEREO; } /* 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->channels) { av_log(avctx, AV_LOG_ERROR, "unable to determine channel mode\n"); return AVERROR_INVALIDDATA; } avctx->channels = s->out_channels; avctx->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode & ~AC3_OUTPUT_LFEON]; if (s->output_mode & AC3_OUTPUT_LFEON) avctx->channel_layout |= AV_CH_LOW_FREQUENCY; /* set audio service type based on bitstream mode for AC-3 */ avctx->audio_service_type = s->bitstream_mode; if (s->bitstream_mode == 0x7 && s->channels > 1) avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE; /* get output buffer */ frame->nb_samples = s->num_blocks * AC3_BLOCK_SIZE; if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) { av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); return ret; } /* decode the audio blocks */ channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on]; for (ch = 0; ch < s->channels; ch++) { if (ch < s->out_channels) s->outptr[channel_map[ch]] = (float *)frame->data[ch]; else s->outptr[ch] = s->output[ch]; output[ch] = s->output[ch]; } for (blk = 0; blk < s->num_blocks; blk++) { if (!err && decode_audio_block(s, blk)) { av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n"); err = 1; } if (err) for (ch = 0; ch < s->out_channels; ch++) memcpy(s->outptr[channel_map[ch]], output[ch], sizeof(**output) * AC3_BLOCK_SIZE); for (ch = 0; ch < s->out_channels; ch++) output[ch] = s->outptr[channel_map[ch]]; for (ch = 0; ch < s->out_channels; ch++) s->outptr[ch] += AC3_BLOCK_SIZE; } /* keep last block for error concealment in next frame */ for (ch = 0; ch < s->out_channels; ch++) memcpy(s->output[ch], output[ch], sizeof(**output) * AC3_BLOCK_SIZE); /* * AVMatrixEncoding * * Check whether the input layout is compatible, and make sure we're not * downmixing (else the matrix encoding is no longer applicable). */ matrix_encoding = AV_MATRIX_ENCODING_NONE; if (s->channel_mode == AC3_CHMODE_STEREO && s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) { if (s->dolby_surround_mode == AC3_DSURMOD_ON) matrix_encoding = AV_MATRIX_ENCODING_DOLBY; else if (s->dolby_headphone_mode == AC3_DHEADPHONMOD_ON) matrix_encoding = AV_MATRIX_ENCODING_DOLBYHEADPHONE; } else if (s->channel_mode >= AC3_CHMODE_2F2R && s->channel_mode == (s->output_mode & ~AC3_OUTPUT_LFEON)) { switch (s->dolby_surround_ex_mode) { case AC3_DSUREXMOD_ON: // EX or PLIIx matrix_encoding = AV_MATRIX_ENCODING_DOLBYEX; break; case AC3_DSUREXMOD_PLIIZ: matrix_encoding = AV_MATRIX_ENCODING_DPLIIZ; break; default: // not indicated or off break; } } if ((ret = ff_side_data_update_matrix_encoding(frame, matrix_encoding)) < 0) return ret; /* AVDownmixInfo */ if ((downmix_info = av_downmix_info_update_side_data(frame))) { switch (s->preferred_downmix) { case AC3_DMIXMOD_LTRT: downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LTRT; break; case AC3_DMIXMOD_LORO: downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_LORO; break; case AC3_DMIXMOD_DPLII: downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_DPLII; break; default: downmix_info->preferred_downmix_type = AV_DOWNMIX_TYPE_UNKNOWN; break; } downmix_info->center_mix_level = gain_levels[s-> center_mix_level]; downmix_info->center_mix_level_ltrt = gain_levels[s-> center_mix_level_ltrt]; downmix_info->surround_mix_level = gain_levels[s-> surround_mix_level]; downmix_info->surround_mix_level_ltrt = gain_levels[s->surround_mix_level_ltrt]; if (s->lfe_mix_level_exists) downmix_info->lfe_mix_level = gain_levels_lfe[s->lfe_mix_level]; else downmix_info->lfe_mix_level = 0.0; // -inf dB } else return AVERROR(ENOMEM); *got_frame_ptr = 1; return FFMIN(buf_size, 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); return 0; } #define OFFSET(x) offsetof(AC3DecodeContext, x) #define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM) static const AVOption options[] = { { "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 6.0, PAR }, { NULL}, }; static const AVClass ac3_decoder_class = { .class_name = "AC3 decoder", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, }; AVCodec ff_ac3_decoder = { .name = "ac3", .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), .type = AVMEDIA_TYPE_AUDIO, .id = AV_CODEC_ID_AC3, .priv_data_size = sizeof (AC3DecodeContext), .init = ac3_decode_init, .close = ac3_decode_end, .decode = ac3_decode_frame, .capabilities = CODEC_CAP_DR1, .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE }, .priv_class = &ac3_decoder_class, }; #if CONFIG_EAC3_DECODER static const AVClass eac3_decoder_class = { .class_name = "E-AC3 decoder", .item_name = av_default_item_name, .option = options, .version = LIBAVUTIL_VERSION_INT, }; AVCodec ff_eac3_decoder = { .name = "eac3", .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"), .type = AVMEDIA_TYPE_AUDIO, .id = AV_CODEC_ID_EAC3, .priv_data_size = sizeof (AC3DecodeContext), .init = ac3_decode_init, .close = ac3_decode_end, .decode = ac3_decode_frame, .capabilities = CODEC_CAP_DR1, .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_NONE }, .priv_class = &eac3_decoder_class, }; #endif