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Diffstat (limited to 'ffmpeg1/libavcodec/ac3dec.c')
| -rw-r--r-- | ffmpeg1/libavcodec/ac3dec.c | 1488 |
1 files changed, 1488 insertions, 0 deletions
diff --git a/ffmpeg1/libavcodec/ac3dec.c b/ffmpeg1/libavcodec/ac3dec.c new file mode 100644 index 0000000..a70d92a --- /dev/null +++ b/ffmpeg1/libavcodec/ac3dec.c @@ -0,0 +1,1488 @@ +/* + * 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 "libavutil/opt.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 +}; + +/** + * 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_dsputil_init(&s->dsp, avctx); + 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 (avctx->channels > 0 && avctx->request_channels > 0 && + avctx->request_channels < avctx->channels && + avctx->request_channels <= 2) { + avctx->channels = avctx->request_channels; + } + 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 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 = 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_mode = hdr.bitstream_mode; + s->channel_mode = hdr.channel_mode; + s->channel_layout = hdr.channel_layout; + 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 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 -1; + } +} + +/** + * 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]; + int *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)>>8)*181)>>8) - 5931008; + 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)) { + s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) * + s->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))) { + 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 -1; + } + 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 -1; + } + + 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 -1; + } + + /* 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 -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->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 -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); + } 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 -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) + 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 -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; + 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]; + + /* 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->dsp.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 -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"); + *got_frame_ptr = 0; + 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; + } + } 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|AV_EF_CAREFUL)) { + /* 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"); + 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 (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; + s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode]; + } + avctx->channels = s->out_channels; + avctx->channel_layout = s->channel_layout; + + s->loro_center_mix_level = gain_levels[s-> center_mix_level]; + s->loro_surround_mix_level = gain_levels[s->surround_mix_level]; + s->ltrt_center_mix_level = LEVEL_MINUS_3DB; + s->ltrt_surround_mix_level = LEVEL_MINUS_3DB; + /* 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; + + /* 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 * 256; + if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) + 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 < AC3_MAX_CHANNELS; ch++) { + output[ch] = s->output[ch]; + s->outptr[ch] = s->output[ch]; + } + for (ch = 0; ch < s->channels; ch++) { + if (ch < s->out_channels) + s->outptr[channel_map[ch]] = (float *)frame->data[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(((float*)frame->data[ch]) + AC3_BLOCK_SIZE*blk, output[ch], 1024); + for (ch = 0; ch < s->out_channels; ch++) + output[ch] = s->outptr[channel_map[ch]]; + for (ch = 0; ch < s->out_channels; ch++) { + if (!ch || channel_map[ch]) + s->outptr[channel_map[ch]] += AC3_BLOCK_SIZE; + } + } + + av_frame_set_decode_error_flags(frame, err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0); + + /* keep last block for error concealment in next frame */ + for (ch = 0; ch < s->out_channels; ch++) + memcpy(s->output[ch], output[ch], 1024); + + *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, 1.0, PAR }, + +{"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 2, 0, "dmix_mode"}, +{"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, +{"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, +{"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, +{"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, + + { 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", + .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, + .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), + .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", + .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, + .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"), + .sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP, + AV_SAMPLE_FMT_NONE }, + .priv_class = &eac3_decoder_class, +}; +#endif |