/* * AC-3 encoder float/fixed template * Copyright (c) 2000 Fabrice Bellard * Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com> * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de> * * 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 */ /** * @file * AC-3 encoder float/fixed template */ #include <stdint.h> /* prototypes for static functions in ac3enc_fixed.c and ac3enc_float.c */ static void scale_coefficients(AC3EncodeContext *s); static void apply_window(DSPContext *dsp, SampleType *output, const SampleType *input, const SampleType *window, unsigned int len); static int normalize_samples(AC3EncodeContext *s); static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len); static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl); int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s) { int ch; FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE * sizeof(*s->windowed_samples), alloc_fail); FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples), alloc_fail); for (ch = 0; ch < s->channels; ch++) { FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch], (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples), alloc_fail); } return 0; alloc_fail: return AVERROR(ENOMEM); } /** * Deinterleave input samples. * Channels are reordered from Libav's default order to AC-3 order. */ static void deinterleave_input_samples(AC3EncodeContext *s, const SampleType *samples) { int ch, i; /* deinterleave and remap input samples */ for (ch = 0; ch < s->channels; ch++) { const SampleType *sptr; int sinc; /* copy last 256 samples of previous frame to the start of the current frame */ memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_BLOCK_SIZE * s->num_blocks], AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0])); /* deinterleave */ sinc = s->channels; sptr = samples + s->channel_map[ch]; for (i = AC3_BLOCK_SIZE; i < AC3_BLOCK_SIZE * (s->num_blocks + 1); i++) { s->planar_samples[ch][i] = *sptr; sptr += sinc; } } } /** * Apply the MDCT to input samples to generate frequency coefficients. * This applies the KBD window and normalizes the input to reduce precision * loss due to fixed-point calculations. */ static void apply_mdct(AC3EncodeContext *s) { int blk, ch; for (ch = 0; ch < s->channels; ch++) { for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE]; apply_window(&s->dsp, s->windowed_samples, input_samples, s->mdct_window, AC3_WINDOW_SIZE); if (s->fixed_point) block->coeff_shift[ch+1] = normalize_samples(s); s->mdct.mdct_calcw(&s->mdct, block->mdct_coef[ch+1], s->windowed_samples); } } } /** * Calculate coupling channel and coupling coordinates. */ static void apply_channel_coupling(AC3EncodeContext *s) { LOCAL_ALIGNED_16(CoefType, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]); #if CONFIG_AC3ENC_FLOAT LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]); #else int32_t (*fixed_cpl_coords)[AC3_MAX_CHANNELS][16] = cpl_coords; #endif int blk, ch, bnd, i, j; CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}}; int cpl_start, num_cpl_coefs; memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords)); #if CONFIG_AC3ENC_FLOAT memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords)); #endif /* align start to 16-byte boundary. align length to multiple of 32. note: coupling start bin % 4 will always be 1 */ cpl_start = s->start_freq[CPL_CH] - 1; num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32); cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs; /* calculate coupling channel from fbw channels */ for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start]; if (!block->cpl_in_use) continue; memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef)); for (ch = 1; ch <= s->fbw_channels; ch++) { CoefType *ch_coef = &block->mdct_coef[ch][cpl_start]; if (!block->channel_in_cpl[ch]) continue; for (i = 0; i < num_cpl_coefs; i++) cpl_coef[i] += ch_coef[i]; } /* coefficients must be clipped in order to be encoded */ clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs); } /* calculate energy in each band in coupling channel and each fbw channel */ /* TODO: possibly use SIMD to speed up energy calculation */ bnd = 0; i = s->start_freq[CPL_CH]; while (i < s->cpl_end_freq) { int band_size = s->cpl_band_sizes[bnd]; for (ch = CPL_CH; ch <= s->fbw_channels; ch++) { for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch])) continue; for (j = 0; j < band_size; j++) { CoefType v = block->mdct_coef[ch][i+j]; MAC_COEF(energy[blk][ch][bnd], v, v); } } } i += band_size; bnd++; } /* calculate coupling coordinates for all blocks for all channels */ for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; if (!block->cpl_in_use) continue; for (ch = 1; ch <= s->fbw_channels; ch++) { if (!block->channel_in_cpl[ch]) continue; for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd], energy[blk][CPL_CH][bnd]); } } } /* determine which blocks to send new coupling coordinates for */ for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL; memset(block->new_cpl_coords, 0, sizeof(block->new_cpl_coords)); if (block->cpl_in_use) { /* send new coordinates if this is the first block, if previous * block did not use coupling but this block does, the channels * using coupling has changed from the previous block, or the * coordinate difference from the last block for any channel is * greater than a threshold value. */ if (blk == 0 || !block0->cpl_in_use) { for (ch = 1; ch <= s->fbw_channels; ch++) block->new_cpl_coords[ch] = 1; } else { for (ch = 1; ch <= s->fbw_channels; ch++) { if (!block->channel_in_cpl[ch]) continue; if (!block0->channel_in_cpl[ch]) { block->new_cpl_coords[ch] = 1; } else { CoefSumType coord_diff = 0; for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { coord_diff += FFABS(cpl_coords[blk-1][ch][bnd] - cpl_coords[blk ][ch][bnd]); } coord_diff /= s->num_cpl_bands; if (coord_diff > NEW_CPL_COORD_THRESHOLD) block->new_cpl_coords[ch] = 1; } } } } } /* calculate final coupling coordinates, taking into account reusing of coordinates in successive blocks */ for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { blk = 0; while (blk < s->num_blocks) { int av_uninit(blk1); AC3Block *block = &s->blocks[blk]; if (!block->cpl_in_use) { blk++; continue; } for (ch = 1; ch <= s->fbw_channels; ch++) { CoefSumType energy_ch, energy_cpl; if (!block->channel_in_cpl[ch]) continue; energy_cpl = energy[blk][CPL_CH][bnd]; energy_ch = energy[blk][ch][bnd]; blk1 = blk+1; while (!s->blocks[blk1].new_cpl_coords[ch] && blk1 < s->num_blocks) { if (s->blocks[blk1].cpl_in_use) { energy_cpl += energy[blk1][CPL_CH][bnd]; energy_ch += energy[blk1][ch][bnd]; } blk1++; } cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl); } blk = blk1; } } /* calculate exponents/mantissas for coupling coordinates */ for (blk = 0; blk < s->num_blocks; blk++) { AC3Block *block = &s->blocks[blk]; if (!block->cpl_in_use) continue; #if CONFIG_AC3ENC_FLOAT s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1], cpl_coords[blk][1], s->fbw_channels * 16); #endif s->ac3dsp.extract_exponents(block->cpl_coord_exp[1], fixed_cpl_coords[blk][1], s->fbw_channels * 16); for (ch = 1; ch <= s->fbw_channels; ch++) { int bnd, min_exp, max_exp, master_exp; if (!block->new_cpl_coords[ch]) continue; /* determine master exponent */ min_exp = max_exp = block->cpl_coord_exp[ch][0]; for (bnd = 1; bnd < s->num_cpl_bands; bnd++) { int exp = block->cpl_coord_exp[ch][bnd]; min_exp = FFMIN(exp, min_exp); max_exp = FFMAX(exp, max_exp); } master_exp = ((max_exp - 15) + 2) / 3; master_exp = FFMAX(master_exp, 0); while (min_exp < master_exp * 3) master_exp--; for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] - master_exp * 3, 0, 15); } block->cpl_master_exp[ch] = master_exp; /* quantize mantissas */ for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { int cpl_exp = block->cpl_coord_exp[ch][bnd]; int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24; if (cpl_exp == 15) cpl_mant >>= 1; else cpl_mant -= 16; block->cpl_coord_mant[ch][bnd] = cpl_mant; } } } if (CONFIG_EAC3_ENCODER && s->eac3) ff_eac3_set_cpl_states(s); } /** * Determine rematrixing flags for each block and band. */ static void compute_rematrixing_strategy(AC3EncodeContext *s) { int nb_coefs; int blk, bnd, i; AC3Block *block, *av_uninit(block0); if (s->channel_mode != AC3_CHMODE_STEREO) return; for (blk = 0; blk < s->num_blocks; blk++) { block = &s->blocks[blk]; block->new_rematrixing_strategy = !blk; block->num_rematrixing_bands = 4; if (block->cpl_in_use) { block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61); block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37); if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands) block->new_rematrixing_strategy = 1; } nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]); if (!s->rematrixing_enabled) { block0 = block; continue; } for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) { /* calculate calculate sum of squared coeffs for one band in one block */ int start = ff_ac3_rematrix_band_tab[bnd]; int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]); CoefSumType sum[4] = {0,}; for (i = start; i < end; i++) { CoefType lt = block->mdct_coef[1][i]; CoefType rt = block->mdct_coef[2][i]; CoefType md = lt + rt; CoefType sd = lt - rt; MAC_COEF(sum[0], lt, lt); MAC_COEF(sum[1], rt, rt); MAC_COEF(sum[2], md, md); MAC_COEF(sum[3], sd, sd); } /* compare sums to determine if rematrixing will be used for this band */ if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1])) block->rematrixing_flags[bnd] = 1; else block->rematrixing_flags[bnd] = 0; /* determine if new rematrixing flags will be sent */ if (blk && block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) { block->new_rematrixing_strategy = 1; } } block0 = block; } } /** * Encode a single AC-3 frame. */ int AC3_NAME(encode_frame)(AVCodecContext *avctx, unsigned char *frame, int buf_size, void *data) { AC3EncodeContext *s = avctx->priv_data; const SampleType *samples = data; int ret; if (s->options.allow_per_frame_metadata) { ret = ff_ac3_validate_metadata(s); if (ret) return ret; } if (s->bit_alloc.sr_code == 1 || s->eac3) ff_ac3_adjust_frame_size(s); deinterleave_input_samples(s, samples); apply_mdct(s); if (s->fixed_point) scale_coefficients(s); clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1], AC3_MAX_COEFS * s->num_blocks * s->channels); s->cpl_on = s->cpl_enabled; ff_ac3_compute_coupling_strategy(s); if (s->cpl_on) apply_channel_coupling(s); compute_rematrixing_strategy(s); if (!s->fixed_point) scale_coefficients(s); ff_ac3_apply_rematrixing(s); ff_ac3_process_exponents(s); ret = ff_ac3_compute_bit_allocation(s); if (ret) { av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n"); return ret; } ff_ac3_group_exponents(s); ff_ac3_quantize_mantissas(s); ff_ac3_output_frame(s, frame); return s->frame_size; }