400 lines
15 KiB
C
400 lines
15 KiB
C
/*
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* AC-3 encoder float/fixed template
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* Copyright (c) 2000 Fabrice Bellard
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* Copyright (c) 2006-2011 Justin Ruggles <justin.ruggles@gmail.com>
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* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* AC-3 encoder float/fixed template
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*/
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#include <stdint.h>
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#include "ac3enc.h"
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int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
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{
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int ch;
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FF_ALLOC_OR_GOTO(s->avctx, s->windowed_samples, AC3_WINDOW_SIZE *
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sizeof(*s->windowed_samples), alloc_fail);
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FF_ALLOC_OR_GOTO(s->avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
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alloc_fail);
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for (ch = 0; ch < s->channels; ch++) {
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FF_ALLOCZ_OR_GOTO(s->avctx, s->planar_samples[ch],
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(AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
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alloc_fail);
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}
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return 0;
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alloc_fail:
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return AVERROR(ENOMEM);
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}
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/**
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* Deinterleave input samples.
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* Channels are reordered from Libav's default order to AC-3 order.
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*/
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void AC3_NAME(deinterleave_input_samples)(AC3EncodeContext *s,
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const SampleType *samples)
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{
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int ch, i;
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/* deinterleave and remap input samples */
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for (ch = 0; ch < s->channels; ch++) {
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const SampleType *sptr;
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int sinc;
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/* copy last 256 samples of previous frame to the start of the current frame */
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memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
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AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
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/* deinterleave */
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sinc = s->channels;
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sptr = samples + s->channel_map[ch];
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for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
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s->planar_samples[ch][i] = *sptr;
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sptr += sinc;
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}
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}
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}
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/**
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* Apply the MDCT to input samples to generate frequency coefficients.
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* This applies the KBD window and normalizes the input to reduce precision
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* loss due to fixed-point calculations.
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*/
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void AC3_NAME(apply_mdct)(AC3EncodeContext *s)
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{
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int blk, ch;
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for (ch = 0; ch < s->channels; ch++) {
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
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s->apply_window(&s->dsp, s->windowed_samples, input_samples,
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s->mdct->window, AC3_WINDOW_SIZE);
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if (s->fixed_point)
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block->coeff_shift[ch+1] = s->normalize_samples(s);
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s->mdct->fft.mdct_calcw(&s->mdct->fft, block->mdct_coef[ch+1],
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s->windowed_samples);
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}
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}
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}
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/**
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* Calculate a single coupling coordinate.
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*/
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static inline float calc_cpl_coord(float energy_ch, float energy_cpl)
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{
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float coord = 0.125;
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if (energy_cpl > 0)
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coord *= sqrtf(energy_ch / energy_cpl);
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return coord;
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}
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/**
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* Calculate coupling channel and coupling coordinates.
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* TODO: Currently this is only used for the floating-point encoder. I was
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* able to make it work for the fixed-point encoder, but quality was
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* generally lower in most cases than not using coupling. If a more
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* adaptive coupling strategy were to be implemented it might be useful
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* at that time to use coupling for the fixed-point encoder as well.
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*/
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void AC3_NAME(apply_channel_coupling)(AC3EncodeContext *s)
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{
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#if CONFIG_AC3ENC_FLOAT
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LOCAL_ALIGNED_16(float, cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
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LOCAL_ALIGNED_16(int32_t, fixed_cpl_coords, [AC3_MAX_BLOCKS], [AC3_MAX_CHANNELS][16]);
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int blk, ch, bnd, i, j;
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CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
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int cpl_start, num_cpl_coefs;
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memset(cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*cpl_coords));
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memset(fixed_cpl_coords, 0, AC3_MAX_BLOCKS * sizeof(*fixed_cpl_coords));
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/* align start to 16-byte boundary. align length to multiple of 32.
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note: coupling start bin % 4 will always be 1 */
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cpl_start = s->start_freq[CPL_CH] - 1;
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num_cpl_coefs = FFALIGN(s->num_cpl_subbands * 12 + 1, 32);
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cpl_start = FFMIN(256, cpl_start + num_cpl_coefs) - num_cpl_coefs;
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/* calculate coupling channel from fbw channels */
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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CoefType *cpl_coef = &block->mdct_coef[CPL_CH][cpl_start];
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if (!block->cpl_in_use)
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continue;
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memset(cpl_coef, 0, num_cpl_coefs * sizeof(*cpl_coef));
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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CoefType *ch_coef = &block->mdct_coef[ch][cpl_start];
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if (!block->channel_in_cpl[ch])
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continue;
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for (i = 0; i < num_cpl_coefs; i++)
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cpl_coef[i] += ch_coef[i];
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}
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/* coefficients must be clipped to +/- 1.0 in order to be encoded */
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s->dsp.vector_clipf(cpl_coef, cpl_coef, -1.0f, 1.0f, num_cpl_coefs);
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/* scale coupling coefficients from float to 24-bit fixed-point */
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s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][cpl_start],
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cpl_coef, num_cpl_coefs);
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}
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/* calculate energy in each band in coupling channel and each fbw channel */
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/* TODO: possibly use SIMD to speed up energy calculation */
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bnd = 0;
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i = s->start_freq[CPL_CH];
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while (i < s->cpl_end_freq) {
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int band_size = s->cpl_band_sizes[bnd];
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for (ch = CPL_CH; ch <= s->fbw_channels; ch++) {
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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if (!block->cpl_in_use || (ch > CPL_CH && !block->channel_in_cpl[ch]))
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continue;
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for (j = 0; j < band_size; j++) {
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CoefType v = block->mdct_coef[ch][i+j];
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MAC_COEF(energy[blk][ch][bnd], v, v);
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}
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}
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}
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i += band_size;
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bnd++;
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}
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/* determine which blocks to send new coupling coordinates for */
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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AC3Block *block0 = blk ? &s->blocks[blk-1] : NULL;
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int new_coords = 0;
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CoefSumType coord_diff[AC3_MAX_CHANNELS] = {0,};
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if (block->cpl_in_use) {
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/* calculate coupling coordinates for all blocks and calculate the
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average difference between coordinates in successive blocks */
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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if (!block->channel_in_cpl[ch])
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continue;
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for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
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cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy[blk][ch][bnd],
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energy[blk][CPL_CH][bnd]);
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if (blk > 0 && block0->cpl_in_use &&
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block0->channel_in_cpl[ch]) {
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coord_diff[ch] += fabs(cpl_coords[blk-1][ch][bnd] -
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cpl_coords[blk ][ch][bnd]);
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}
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}
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coord_diff[ch] /= s->num_cpl_bands;
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}
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/* send new coordinates if this is the first block, if previous
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* block did not use coupling but this block does, the channels
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* using coupling has changed from the previous block, or the
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* coordinate difference from the last block for any channel is
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* greater than a threshold value. */
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if (blk == 0) {
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new_coords = 1;
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} else if (!block0->cpl_in_use) {
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new_coords = 1;
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} else {
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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if (block->channel_in_cpl[ch] && !block0->channel_in_cpl[ch]) {
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new_coords = 1;
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break;
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}
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}
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if (!new_coords) {
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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if (block->channel_in_cpl[ch] && coord_diff[ch] > 0.04) {
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new_coords = 1;
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break;
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}
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}
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}
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}
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}
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block->new_cpl_coords = new_coords;
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}
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/* calculate final coupling coordinates, taking into account reusing of
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coordinates in successive blocks */
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for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
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blk = 0;
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while (blk < AC3_MAX_BLOCKS) {
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int blk1;
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CoefSumType energy_cpl;
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AC3Block *block = &s->blocks[blk];
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if (!block->cpl_in_use) {
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blk++;
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continue;
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}
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energy_cpl = energy[blk][CPL_CH][bnd];
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blk1 = blk+1;
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while (!s->blocks[blk1].new_cpl_coords && blk1 < AC3_MAX_BLOCKS) {
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if (s->blocks[blk1].cpl_in_use)
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energy_cpl += energy[blk1][CPL_CH][bnd];
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blk1++;
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}
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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CoefType energy_ch;
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if (!block->channel_in_cpl[ch])
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continue;
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energy_ch = energy[blk][ch][bnd];
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blk1 = blk+1;
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while (!s->blocks[blk1].new_cpl_coords && blk1 < AC3_MAX_BLOCKS) {
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if (s->blocks[blk1].cpl_in_use)
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energy_ch += energy[blk1][ch][bnd];
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blk1++;
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}
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cpl_coords[blk][ch][bnd] = calc_cpl_coord(energy_ch, energy_cpl);
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}
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blk = blk1;
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}
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}
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/* calculate exponents/mantissas for coupling coordinates */
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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AC3Block *block = &s->blocks[blk];
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if (!block->cpl_in_use || !block->new_cpl_coords)
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continue;
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s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
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cpl_coords[blk][1],
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s->fbw_channels * 16);
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s->ac3dsp.extract_exponents(block->cpl_coord_exp[1],
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fixed_cpl_coords[blk][1],
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s->fbw_channels * 16);
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for (ch = 1; ch <= s->fbw_channels; ch++) {
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int bnd, min_exp, max_exp, master_exp;
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/* determine master exponent */
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min_exp = max_exp = block->cpl_coord_exp[ch][0];
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for (bnd = 1; bnd < s->num_cpl_bands; bnd++) {
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int exp = block->cpl_coord_exp[ch][bnd];
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min_exp = FFMIN(exp, min_exp);
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max_exp = FFMAX(exp, max_exp);
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}
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master_exp = ((max_exp - 15) + 2) / 3;
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master_exp = FFMAX(master_exp, 0);
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while (min_exp < master_exp * 3)
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master_exp--;
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for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
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block->cpl_coord_exp[ch][bnd] = av_clip(block->cpl_coord_exp[ch][bnd] -
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master_exp * 3, 0, 15);
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}
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block->cpl_master_exp[ch] = master_exp;
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/* quantize mantissas */
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for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
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int cpl_exp = block->cpl_coord_exp[ch][bnd];
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int cpl_mant = (fixed_cpl_coords[blk][ch][bnd] << (5 + cpl_exp + master_exp * 3)) >> 24;
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if (cpl_exp == 15)
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cpl_mant >>= 1;
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else
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cpl_mant -= 16;
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block->cpl_coord_mant[ch][bnd] = cpl_mant;
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}
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}
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}
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if (CONFIG_EAC3_ENCODER && s->eac3)
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ff_eac3_set_cpl_states(s);
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#endif /* CONFIG_AC3ENC_FLOAT */
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}
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/**
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* Determine rematrixing flags for each block and band.
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*/
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void AC3_NAME(compute_rematrixing_strategy)(AC3EncodeContext *s)
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{
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int nb_coefs;
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int blk, bnd, i;
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AC3Block *block, *av_uninit(block0);
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if (s->channel_mode != AC3_CHMODE_STEREO)
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return;
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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block = &s->blocks[blk];
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block->new_rematrixing_strategy = !blk;
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if (!s->rematrixing_enabled) {
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block0 = block;
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continue;
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}
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block->num_rematrixing_bands = 4;
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if (block->cpl_in_use) {
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block->num_rematrixing_bands -= (s->start_freq[CPL_CH] <= 61);
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block->num_rematrixing_bands -= (s->start_freq[CPL_CH] == 37);
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if (blk && block->num_rematrixing_bands != block0->num_rematrixing_bands)
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block->new_rematrixing_strategy = 1;
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}
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nb_coefs = FFMIN(block->end_freq[1], block->end_freq[2]);
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for (bnd = 0; bnd < block->num_rematrixing_bands; bnd++) {
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/* calculate calculate sum of squared coeffs for one band in one block */
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int start = ff_ac3_rematrix_band_tab[bnd];
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int end = FFMIN(nb_coefs, ff_ac3_rematrix_band_tab[bnd+1]);
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CoefSumType sum[4] = {0,};
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for (i = start; i < end; i++) {
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CoefType lt = block->mdct_coef[1][i];
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CoefType rt = block->mdct_coef[2][i];
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CoefType md = lt + rt;
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CoefType sd = lt - rt;
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MAC_COEF(sum[0], lt, lt);
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MAC_COEF(sum[1], rt, rt);
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MAC_COEF(sum[2], md, md);
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MAC_COEF(sum[3], sd, sd);
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}
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/* compare sums to determine if rematrixing will be used for this band */
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if (FFMIN(sum[2], sum[3]) < FFMIN(sum[0], sum[1]))
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block->rematrixing_flags[bnd] = 1;
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else
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block->rematrixing_flags[bnd] = 0;
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/* determine if new rematrixing flags will be sent */
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if (blk &&
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block->rematrixing_flags[bnd] != block0->rematrixing_flags[bnd]) {
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block->new_rematrixing_strategy = 1;
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}
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}
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block0 = block;
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}
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}
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