/** * FLAC audio encoder * Copyright (c) 2006 Justin Ruggles * * 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 "avcodec.h" #include "bitstream.h" #include "crc.h" #include "golomb.h" #include "lls.h" #define FLAC_MAX_CH 8 #define FLAC_MIN_BLOCKSIZE 16 #define FLAC_MAX_BLOCKSIZE 65535 #define FLAC_SUBFRAME_CONSTANT 0 #define FLAC_SUBFRAME_VERBATIM 1 #define FLAC_SUBFRAME_FIXED 8 #define FLAC_SUBFRAME_LPC 32 #define FLAC_CHMODE_NOT_STEREO 0 #define FLAC_CHMODE_LEFT_RIGHT 1 #define FLAC_CHMODE_LEFT_SIDE 8 #define FLAC_CHMODE_RIGHT_SIDE 9 #define FLAC_CHMODE_MID_SIDE 10 #define ORDER_METHOD_EST 0 #define ORDER_METHOD_2LEVEL 1 #define ORDER_METHOD_4LEVEL 2 #define ORDER_METHOD_8LEVEL 3 #define ORDER_METHOD_SEARCH 4 #define ORDER_METHOD_LOG 5 #define FLAC_STREAMINFO_SIZE 34 #define MIN_LPC_ORDER 1 #define MAX_LPC_ORDER 32 #define MAX_FIXED_ORDER 4 #define MAX_PARTITION_ORDER 8 #define MAX_PARTITIONS (1 << MAX_PARTITION_ORDER) #define MAX_LPC_PRECISION 15 #define MAX_LPC_SHIFT 15 #define MAX_RICE_PARAM 14 typedef struct CompressionOptions { int compression_level; int block_time_ms; int use_lpc; int lpc_coeff_precision; int min_prediction_order; int max_prediction_order; int prediction_order_method; int min_partition_order; int max_partition_order; } CompressionOptions; typedef struct RiceContext { int porder; int params[MAX_PARTITIONS]; } RiceContext; typedef struct FlacSubframe { int type; int type_code; int obits; int order; int32_t coefs[MAX_LPC_ORDER]; int shift; RiceContext rc; int32_t samples[FLAC_MAX_BLOCKSIZE]; int32_t residual[FLAC_MAX_BLOCKSIZE]; } FlacSubframe; typedef struct FlacFrame { FlacSubframe subframes[FLAC_MAX_CH]; int blocksize; int bs_code[2]; uint8_t crc8; int ch_mode; } FlacFrame; typedef struct FlacEncodeContext { PutBitContext pb; int channels; int ch_code; int samplerate; int sr_code[2]; int blocksize; int max_framesize; uint32_t frame_count; FlacFrame frame; CompressionOptions options; AVCodecContext *avctx; } FlacEncodeContext; static const int flac_samplerates[16] = { 0, 0, 0, 0, 8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000, 0, 0, 0, 0 }; static const int flac_blocksizes[16] = { 0, 192, 576, 1152, 2304, 4608, 0, 0, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768 }; /** * Writes streaminfo metadata block to byte array */ static void write_streaminfo(FlacEncodeContext *s, uint8_t *header) { PutBitContext pb; memset(header, 0, FLAC_STREAMINFO_SIZE); init_put_bits(&pb, header, FLAC_STREAMINFO_SIZE); /* streaminfo metadata block */ put_bits(&pb, 16, s->blocksize); put_bits(&pb, 16, s->blocksize); put_bits(&pb, 24, 0); put_bits(&pb, 24, s->max_framesize); put_bits(&pb, 20, s->samplerate); put_bits(&pb, 3, s->channels-1); put_bits(&pb, 5, 15); /* bits per sample - 1 */ flush_put_bits(&pb); /* total samples = 0 */ /* MD5 signature = 0 */ } /** * Sets blocksize based on samplerate * Chooses the closest predefined blocksize >= BLOCK_TIME_MS milliseconds */ static int select_blocksize(int samplerate, int block_time_ms) { int i; int target; int blocksize; assert(samplerate > 0); blocksize = flac_blocksizes[1]; target = (samplerate * block_time_ms) / 1000; for(i=0; i<16; i++) { if(target >= flac_blocksizes[i] && flac_blocksizes[i] > blocksize) { blocksize = flac_blocksizes[i]; } } return blocksize; } static int flac_encode_init(AVCodecContext *avctx) { int freq = avctx->sample_rate; int channels = avctx->channels; FlacEncodeContext *s = avctx->priv_data; int i, level; uint8_t *streaminfo; s->avctx = avctx; if(avctx->sample_fmt != SAMPLE_FMT_S16) { return -1; } if(channels < 1 || channels > FLAC_MAX_CH) { return -1; } s->channels = channels; s->ch_code = s->channels-1; /* find samplerate in table */ if(freq < 1) return -1; for(i=4; i<12; i++) { if(freq == flac_samplerates[i]) { s->samplerate = flac_samplerates[i]; s->sr_code[0] = i; s->sr_code[1] = 0; break; } } /* if not in table, samplerate is non-standard */ if(i == 12) { if(freq % 1000 == 0 && freq < 255000) { s->sr_code[0] = 12; s->sr_code[1] = freq / 1000; } else if(freq % 10 == 0 && freq < 655350) { s->sr_code[0] = 14; s->sr_code[1] = freq / 10; } else if(freq < 65535) { s->sr_code[0] = 13; s->sr_code[1] = freq; } else { return -1; } s->samplerate = freq; } /* set compression option defaults based on avctx->compression_level */ if(avctx->compression_level < 0) { s->options.compression_level = 5; } else { s->options.compression_level = avctx->compression_level; } av_log(avctx, AV_LOG_DEBUG, " compression: %d\n", s->options.compression_level); level= s->options.compression_level; if(level > 12) { av_log(avctx, AV_LOG_ERROR, "invalid compression level: %d\n", s->options.compression_level); return -1; } s->options.block_time_ms = ((int[]){ 27, 27, 27,105,105,105,105,105,105,105,105,105,105})[level]; s->options.use_lpc = ((int[]){ 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})[level]; s->options.min_prediction_order= ((int[]){ 2, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})[level]; s->options.max_prediction_order= ((int[]){ 3, 4, 4, 6, 8, 8, 8, 8, 12, 12, 12, 32, 32})[level]; s->options.prediction_order_method = ((int[]){ ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_EST, ORDER_METHOD_4LEVEL, ORDER_METHOD_LOG, ORDER_METHOD_4LEVEL, ORDER_METHOD_LOG, ORDER_METHOD_SEARCH, ORDER_METHOD_LOG, ORDER_METHOD_SEARCH})[level]; s->options.min_partition_order = ((int[]){ 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})[level]; s->options.max_partition_order = ((int[]){ 2, 2, 3, 3, 3, 8, 8, 8, 8, 8, 8, 8, 8})[level]; /* set compression option overrides from AVCodecContext */ if(avctx->use_lpc >= 0) { s->options.use_lpc = av_clip(avctx->use_lpc, 0, 11); } if(s->options.use_lpc == 1) av_log(avctx, AV_LOG_DEBUG, " use lpc: Levinson-Durbin recursion with Welch window\n"); else if(s->options.use_lpc > 1) av_log(avctx, AV_LOG_DEBUG, " use lpc: Cholesky factorization\n"); if(avctx->min_prediction_order >= 0) { if(s->options.use_lpc) { if(avctx->min_prediction_order < MIN_LPC_ORDER || avctx->min_prediction_order > MAX_LPC_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n", avctx->min_prediction_order); return -1; } } else { if(avctx->min_prediction_order > MAX_FIXED_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid min prediction order: %d\n", avctx->min_prediction_order); return -1; } } s->options.min_prediction_order = avctx->min_prediction_order; } if(avctx->max_prediction_order >= 0) { if(s->options.use_lpc) { if(avctx->max_prediction_order < MIN_LPC_ORDER || avctx->max_prediction_order > MAX_LPC_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n", avctx->max_prediction_order); return -1; } } else { if(avctx->max_prediction_order > MAX_FIXED_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid max prediction order: %d\n", avctx->max_prediction_order); return -1; } } s->options.max_prediction_order = avctx->max_prediction_order; } if(s->options.max_prediction_order < s->options.min_prediction_order) { av_log(avctx, AV_LOG_ERROR, "invalid prediction orders: min=%d max=%d\n", s->options.min_prediction_order, s->options.max_prediction_order); return -1; } av_log(avctx, AV_LOG_DEBUG, " prediction order: %d, %d\n", s->options.min_prediction_order, s->options.max_prediction_order); if(avctx->prediction_order_method >= 0) { if(avctx->prediction_order_method > ORDER_METHOD_LOG) { av_log(avctx, AV_LOG_ERROR, "invalid prediction order method: %d\n", avctx->prediction_order_method); return -1; } s->options.prediction_order_method = avctx->prediction_order_method; } switch(s->options.prediction_order_method) { case ORDER_METHOD_EST: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "estimate"); break; case ORDER_METHOD_2LEVEL: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "2-level"); break; case ORDER_METHOD_4LEVEL: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "4-level"); break; case ORDER_METHOD_8LEVEL: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "8-level"); break; case ORDER_METHOD_SEARCH: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "full search"); break; case ORDER_METHOD_LOG: av_log(avctx, AV_LOG_DEBUG, " order method: %s\n", "log search"); break; } if(avctx->min_partition_order >= 0) { if(avctx->min_partition_order > MAX_PARTITION_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid min partition order: %d\n", avctx->min_partition_order); return -1; } s->options.min_partition_order = avctx->min_partition_order; } if(avctx->max_partition_order >= 0) { if(avctx->max_partition_order > MAX_PARTITION_ORDER) { av_log(avctx, AV_LOG_ERROR, "invalid max partition order: %d\n", avctx->max_partition_order); return -1; } s->options.max_partition_order = avctx->max_partition_order; } if(s->options.max_partition_order < s->options.min_partition_order) { av_log(avctx, AV_LOG_ERROR, "invalid partition orders: min=%d max=%d\n", s->options.min_partition_order, s->options.max_partition_order); return -1; } av_log(avctx, AV_LOG_DEBUG, " partition order: %d, %d\n", s->options.min_partition_order, s->options.max_partition_order); if(avctx->frame_size > 0) { if(avctx->frame_size < FLAC_MIN_BLOCKSIZE || avctx->frame_size > FLAC_MAX_BLOCKSIZE) { av_log(avctx, AV_LOG_ERROR, "invalid block size: %d\n", avctx->frame_size); return -1; } s->blocksize = avctx->frame_size; } else { s->blocksize = select_blocksize(s->samplerate, s->options.block_time_ms); avctx->frame_size = s->blocksize; } av_log(avctx, AV_LOG_DEBUG, " block size: %d\n", s->blocksize); /* set LPC precision */ if(avctx->lpc_coeff_precision > 0) { if(avctx->lpc_coeff_precision > MAX_LPC_PRECISION) { av_log(avctx, AV_LOG_ERROR, "invalid lpc coeff precision: %d\n", avctx->lpc_coeff_precision); return -1; } s->options.lpc_coeff_precision = avctx->lpc_coeff_precision; } else { /* select LPC precision based on block size */ if( s->blocksize <= 192) s->options.lpc_coeff_precision = 7; else if(s->blocksize <= 384) s->options.lpc_coeff_precision = 8; else if(s->blocksize <= 576) s->options.lpc_coeff_precision = 9; else if(s->blocksize <= 1152) s->options.lpc_coeff_precision = 10; else if(s->blocksize <= 2304) s->options.lpc_coeff_precision = 11; else if(s->blocksize <= 4608) s->options.lpc_coeff_precision = 12; else if(s->blocksize <= 8192) s->options.lpc_coeff_precision = 13; else if(s->blocksize <= 16384) s->options.lpc_coeff_precision = 14; else s->options.lpc_coeff_precision = 15; } av_log(avctx, AV_LOG_DEBUG, " lpc precision: %d\n", s->options.lpc_coeff_precision); /* set maximum encoded frame size in verbatim mode */ if(s->channels == 2) { s->max_framesize = 14 + ((s->blocksize * 33 + 7) >> 3); } else { s->max_framesize = 14 + (s->blocksize * s->channels * 2); } streaminfo = av_malloc(FLAC_STREAMINFO_SIZE); write_streaminfo(s, streaminfo); avctx->extradata = streaminfo; avctx->extradata_size = FLAC_STREAMINFO_SIZE; s->frame_count = 0; avctx->coded_frame = avcodec_alloc_frame(); avctx->coded_frame->key_frame = 1; return 0; } static void init_frame(FlacEncodeContext *s) { int i, ch; FlacFrame *frame; frame = &s->frame; for(i=0; i<16; i++) { if(s->blocksize == flac_blocksizes[i]) { frame->blocksize = flac_blocksizes[i]; frame->bs_code[0] = i; frame->bs_code[1] = 0; break; } } if(i == 16) { frame->blocksize = s->blocksize; if(frame->blocksize <= 256) { frame->bs_code[0] = 6; frame->bs_code[1] = frame->blocksize-1; } else { frame->bs_code[0] = 7; frame->bs_code[1] = frame->blocksize-1; } } for(ch=0; chchannels; ch++) { frame->subframes[ch].obits = 16; } } /** * Copy channel-interleaved input samples into separate subframes */ static void copy_samples(FlacEncodeContext *s, int16_t *samples) { int i, j, ch; FlacFrame *frame; frame = &s->frame; for(i=0,j=0; iblocksize; i++) { for(ch=0; chchannels; ch++,j++) { frame->subframes[ch].samples[i] = samples[j]; } } } #define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k))) static int find_optimal_param(uint32_t sum, int n) { int k, k_opt; uint32_t nbits[MAX_RICE_PARAM+1]; k_opt = 0; nbits[0] = UINT32_MAX; for(k=0; k<=MAX_RICE_PARAM; k++) { nbits[k] = rice_encode_count(sum, n, k); if(nbits[k] < nbits[k_opt]) { k_opt = k; } } return k_opt; } static uint32_t calc_optimal_rice_params(RiceContext *rc, int porder, uint32_t *sums, int n, int pred_order) { int i; int k, cnt, part; uint32_t all_bits; part = (1 << porder); all_bits = 0; cnt = (n >> porder) - pred_order; for(i=0; i> porder); k = find_optimal_param(sums[i], cnt); rc->params[i] = k; all_bits += rice_encode_count(sums[i], cnt, k); } all_bits += (4 * part); rc->porder = porder; return all_bits; } static void calc_sums(int pmin, int pmax, uint32_t *data, int n, int pred_order, uint32_t sums[][MAX_PARTITIONS]) { int i, j; int parts; uint32_t *res, *res_end; /* sums for highest level */ parts = (1 << pmax); res = &data[pred_order]; res_end = &data[n >> pmax]; for(i=0; i> pmax; } /* sums for lower levels */ for(i=pmax-1; i>=pmin; i--) { parts = (1 << i); for(j=0; j= 0 && pmin <= MAX_PARTITION_ORDER); assert(pmax >= 0 && pmax <= MAX_PARTITION_ORDER); assert(pmin <= pmax); udata = av_malloc(n * sizeof(uint32_t)); for(i=0; i>31); } calc_sums(pmin, pmax, udata, n, pred_order, sums); opt_porder = pmin; bits[pmin] = UINT32_MAX; for(i=pmin; i<=pmax; i++) { bits[i] = calc_optimal_rice_params(&tmp_rc, i, sums[i], n, pred_order); if(bits[i] <= bits[opt_porder]) { opt_porder = i; *rc= tmp_rc; } } av_freep(&udata); return bits[opt_porder]; } static int get_max_p_order(int max_porder, int n, int order) { int porder = FFMIN(max_porder, av_log2(n^(n-1))); if(order > 0) porder = FFMIN(porder, av_log2(n/order)); return porder; } static uint32_t calc_rice_params_fixed(RiceContext *rc, int pmin, int pmax, int32_t *data, int n, int pred_order, int bps) { uint32_t bits; pmin = get_max_p_order(pmin, n, pred_order); pmax = get_max_p_order(pmax, n, pred_order); bits = pred_order*bps + 6; bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order); return bits; } static uint32_t calc_rice_params_lpc(RiceContext *rc, int pmin, int pmax, int32_t *data, int n, int pred_order, int bps, int precision) { uint32_t bits; pmin = get_max_p_order(pmin, n, pred_order); pmax = get_max_p_order(pmax, n, pred_order); bits = pred_order*bps + 4 + 5 + pred_order*precision + 6; bits += calc_rice_params(rc, pmin, pmax, data, n, pred_order); return bits; } /** * Apply Welch window function to audio block */ static void apply_welch_window(const int32_t *data, int len, double *w_data) { int i, n2; double w; double c; n2 = (len >> 1); c = 2.0 / (len - 1.0); for(i=0; i> 1); lpc_tmp[i] = r; for(j=0; j qmax) && (sh > 0)) { sh--; } /* since negative shift values are unsupported in decoder, scale down coefficients instead */ if(sh == 0 && cmax > qmax) { double scale = ((double)qmax) / cmax; for(i=0; i=0; i--) { if(ref[i] > 0.10) { est = i+1; break; } } return est; } /** * Calculate LPC coefficients for multiple orders */ static int lpc_calc_coefs(const int32_t *samples, int blocksize, int max_order, int precision, int32_t coefs[][MAX_LPC_ORDER], int *shift, int use_lpc, int omethod) { double autoc[MAX_LPC_ORDER+1]; double ref[MAX_LPC_ORDER]; double lpc[MAX_LPC_ORDER][MAX_LPC_ORDER]; int i, j, pass; int opt_order; assert(max_order >= MIN_LPC_ORDER && max_order <= MAX_LPC_ORDER); if(use_lpc == 1){ compute_autocorr(samples, blocksize, max_order+1, autoc); compute_lpc_coefs(autoc, max_order, lpc, ref); }else{ LLSModel m[2]; double var[MAX_LPC_ORDER+1], eval, weight; for(pass=0; pass>pass) + fabs(eval - var[0]); for(j=0; j<=max_order; j++) var[j]/= sqrt(eval); weight += 1/eval; }else weight++; av_update_lls(&m[pass&1], var, 1.0); } av_solve_lls(&m[pass&1], 0.001, 0); } for(i=0; i0; i--) ref[i] = ref[i-1] - ref[i]; } opt_order = max_order; if(omethod == ORDER_METHOD_EST) { opt_order = estimate_best_order(ref, max_order); i = opt_order-1; quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i]); } else { for(i=0; i 0); memcpy(res, smp, n * sizeof(int32_t)); } static void encode_residual_fixed(int32_t *res, const int32_t *smp, int n, int order) { int i; for(i=0; i> shift); } } static int encode_residual(FlacEncodeContext *ctx, int ch) { int i, n; int min_order, max_order, opt_order, precision, omethod; int min_porder, max_porder; FlacFrame *frame; FlacSubframe *sub; int32_t coefs[MAX_LPC_ORDER][MAX_LPC_ORDER]; int shift[MAX_LPC_ORDER]; int32_t *res, *smp; frame = &ctx->frame; sub = &frame->subframes[ch]; res = sub->residual; smp = sub->samples; n = frame->blocksize; /* CONSTANT */ for(i=1; itype = sub->type_code = FLAC_SUBFRAME_CONSTANT; res[0] = smp[0]; return sub->obits; } /* VERBATIM */ if(n < 5) { sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM; encode_residual_verbatim(res, smp, n); return sub->obits * n; } min_order = ctx->options.min_prediction_order; max_order = ctx->options.max_prediction_order; min_porder = ctx->options.min_partition_order; max_porder = ctx->options.max_partition_order; precision = ctx->options.lpc_coeff_precision; omethod = ctx->options.prediction_order_method; /* FIXED */ if(!ctx->options.use_lpc || max_order == 0 || (n <= max_order)) { uint32_t bits[MAX_FIXED_ORDER+1]; if(max_order > MAX_FIXED_ORDER) max_order = MAX_FIXED_ORDER; opt_order = 0; bits[0] = UINT32_MAX; for(i=min_order; i<=max_order; i++) { encode_residual_fixed(res, smp, n, i); bits[i] = calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res, n, i, sub->obits); if(bits[i] < bits[opt_order]) { opt_order = i; } } sub->order = opt_order; sub->type = FLAC_SUBFRAME_FIXED; sub->type_code = sub->type | sub->order; if(sub->order != max_order) { encode_residual_fixed(res, smp, n, sub->order); return calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res, n, sub->order, sub->obits); } return bits[sub->order]; } /* LPC */ opt_order = lpc_calc_coefs(smp, n, max_order, precision, coefs, shift, ctx->options.use_lpc, omethod); if(omethod == ORDER_METHOD_2LEVEL || omethod == ORDER_METHOD_4LEVEL || omethod == ORDER_METHOD_8LEVEL) { int levels = 1 << omethod; uint32_t bits[levels]; int order; int opt_index = levels-1; opt_order = max_order-1; bits[opt_index] = UINT32_MAX; for(i=levels-1; i>=0; i--) { order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1; if(order < 0) order = 0; encode_residual_lpc(res, smp, n, order+1, coefs[order], shift[order]); bits[i] = calc_rice_params_lpc(&sub->rc, min_porder, max_porder, res, n, order+1, sub->obits, precision); if(bits[i] < bits[opt_index]) { opt_index = i; opt_order = order; } } opt_order++; } else if(omethod == ORDER_METHOD_SEARCH) { // brute-force optimal order search uint32_t bits[MAX_LPC_ORDER]; opt_order = 0; bits[0] = UINT32_MAX; for(i=min_order-1; irc, min_porder, max_porder, res, n, i+1, sub->obits, precision); if(bits[i] < bits[opt_order]) { opt_order = i; } } opt_order++; } else if(omethod == ORDER_METHOD_LOG) { uint32_t bits[MAX_LPC_ORDER]; int step; opt_order= min_order - 1 + (max_order-min_order)/3; memset(bits, -1, sizeof(bits)); for(step=16 ;step; step>>=1){ int last= opt_order; for(i=last-step; i<=last+step; i+= step){ if(i=max_order || bits[i] < UINT32_MAX) continue; encode_residual_lpc(res, smp, n, i+1, coefs[i], shift[i]); bits[i] = calc_rice_params_lpc(&sub->rc, min_porder, max_porder, res, n, i+1, sub->obits, precision); if(bits[i] < bits[opt_order]) opt_order= i; } } opt_order++; } sub->order = opt_order; sub->type = FLAC_SUBFRAME_LPC; sub->type_code = sub->type | (sub->order-1); sub->shift = shift[sub->order-1]; for(i=0; iorder; i++) { sub->coefs[i] = coefs[sub->order-1][i]; } encode_residual_lpc(res, smp, n, sub->order, sub->coefs, sub->shift); return calc_rice_params_lpc(&sub->rc, min_porder, max_porder, res, n, sub->order, sub->obits, precision); } static int encode_residual_v(FlacEncodeContext *ctx, int ch) { int i, n; FlacFrame *frame; FlacSubframe *sub; int32_t *res, *smp; frame = &ctx->frame; sub = &frame->subframes[ch]; res = sub->residual; smp = sub->samples; n = frame->blocksize; /* CONSTANT */ for(i=1; itype = sub->type_code = FLAC_SUBFRAME_CONSTANT; res[0] = smp[0]; return sub->obits; } /* VERBATIM */ sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM; encode_residual_verbatim(res, smp, n); return sub->obits * n; } static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n) { int i, best; int32_t lt, rt; uint64_t sum[4]; uint64_t score[4]; int k; /* calculate sum of 2nd order residual for each channel */ sum[0] = sum[1] = sum[2] = sum[3] = 0; for(i=2; i> 1); sum[3] += FFABS(lt - rt); sum[0] += FFABS(lt); sum[1] += FFABS(rt); } /* estimate bit counts */ for(i=0; i<4; i++) { k = find_optimal_param(2*sum[i], n); sum[i] = rice_encode_count(2*sum[i], n, k); } /* calculate score for each mode */ score[0] = sum[0] + sum[1]; score[1] = sum[0] + sum[3]; score[2] = sum[1] + sum[3]; score[3] = sum[2] + sum[3]; /* return mode with lowest score */ best = 0; for(i=1; i<4; i++) { if(score[i] < score[best]) { best = i; } } if(best == 0) { return FLAC_CHMODE_LEFT_RIGHT; } else if(best == 1) { return FLAC_CHMODE_LEFT_SIDE; } else if(best == 2) { return FLAC_CHMODE_RIGHT_SIDE; } else { return FLAC_CHMODE_MID_SIDE; } } /** * Perform stereo channel decorrelation */ static void channel_decorrelation(FlacEncodeContext *ctx) { FlacFrame *frame; int32_t *left, *right; int i, n; frame = &ctx->frame; n = frame->blocksize; left = frame->subframes[0].samples; right = frame->subframes[1].samples; if(ctx->channels != 2) { frame->ch_mode = FLAC_CHMODE_NOT_STEREO; return; } frame->ch_mode = estimate_stereo_mode(left, right, n); /* perform decorrelation and adjust bits-per-sample */ if(frame->ch_mode == FLAC_CHMODE_LEFT_RIGHT) { return; } if(frame->ch_mode == FLAC_CHMODE_MID_SIDE) { int32_t tmp; for(i=0; i> 1; right[i] = tmp - right[i]; } frame->subframes[1].obits++; } else if(frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) { for(i=0; isubframes[1].obits++; } else { for(i=0; isubframes[0].obits++; } } static void put_sbits(PutBitContext *pb, int bits, int32_t val) { assert(bits >= 0 && bits <= 31); put_bits(pb, bits, val & ((1<frame; put_bits(&s->pb, 16, 0xFFF8); put_bits(&s->pb, 4, frame->bs_code[0]); put_bits(&s->pb, 4, s->sr_code[0]); if(frame->ch_mode == FLAC_CHMODE_NOT_STEREO) { put_bits(&s->pb, 4, s->ch_code); } else { put_bits(&s->pb, 4, frame->ch_mode); } put_bits(&s->pb, 3, 4); /* bits-per-sample code */ put_bits(&s->pb, 1, 0); write_utf8(&s->pb, s->frame_count); if(frame->bs_code[0] == 6) { put_bits(&s->pb, 8, frame->bs_code[1]); } else if(frame->bs_code[0] == 7) { put_bits(&s->pb, 16, frame->bs_code[1]); } if(s->sr_code[0] == 12) { put_bits(&s->pb, 8, s->sr_code[1]); } else if(s->sr_code[0] > 12) { put_bits(&s->pb, 16, s->sr_code[1]); } flush_put_bits(&s->pb); crc = av_crc(av_crc07, 0, s->pb.buf, put_bits_count(&s->pb)>>3); put_bits(&s->pb, 8, crc); } static void output_subframe_constant(FlacEncodeContext *s, int ch) { FlacSubframe *sub; int32_t res; sub = &s->frame.subframes[ch]; res = sub->residual[0]; put_sbits(&s->pb, sub->obits, res); } static void output_subframe_verbatim(FlacEncodeContext *s, int ch) { int i; FlacFrame *frame; FlacSubframe *sub; int32_t res; frame = &s->frame; sub = &frame->subframes[ch]; for(i=0; iblocksize; i++) { res = sub->residual[i]; put_sbits(&s->pb, sub->obits, res); } } static void output_residual(FlacEncodeContext *ctx, int ch) { int i, j, p, n, parts; int k, porder, psize, res_cnt; FlacFrame *frame; FlacSubframe *sub; int32_t *res; frame = &ctx->frame; sub = &frame->subframes[ch]; res = sub->residual; n = frame->blocksize; /* rice-encoded block */ put_bits(&ctx->pb, 2, 0); /* partition order */ porder = sub->rc.porder; psize = n >> porder; parts = (1 << porder); put_bits(&ctx->pb, 4, porder); res_cnt = psize - sub->order; /* residual */ j = sub->order; for(p=0; prc.params[p]; put_bits(&ctx->pb, 4, k); if(p == 1) res_cnt = psize; for(i=0; ipb, res[j], k, INT32_MAX, 0); } } } static void output_subframe_fixed(FlacEncodeContext *ctx, int ch) { int i; FlacFrame *frame; FlacSubframe *sub; frame = &ctx->frame; sub = &frame->subframes[ch]; /* warm-up samples */ for(i=0; iorder; i++) { put_sbits(&ctx->pb, sub->obits, sub->residual[i]); } /* residual */ output_residual(ctx, ch); } static void output_subframe_lpc(FlacEncodeContext *ctx, int ch) { int i, cbits; FlacFrame *frame; FlacSubframe *sub; frame = &ctx->frame; sub = &frame->subframes[ch]; /* warm-up samples */ for(i=0; iorder; i++) { put_sbits(&ctx->pb, sub->obits, sub->residual[i]); } /* LPC coefficients */ cbits = ctx->options.lpc_coeff_precision; put_bits(&ctx->pb, 4, cbits-1); put_sbits(&ctx->pb, 5, sub->shift); for(i=0; iorder; i++) { put_sbits(&ctx->pb, cbits, sub->coefs[i]); } /* residual */ output_residual(ctx, ch); } static void output_subframes(FlacEncodeContext *s) { FlacFrame *frame; FlacSubframe *sub; int ch; frame = &s->frame; for(ch=0; chchannels; ch++) { sub = &frame->subframes[ch]; /* subframe header */ put_bits(&s->pb, 1, 0); put_bits(&s->pb, 6, sub->type_code); put_bits(&s->pb, 1, 0); /* no wasted bits */ /* subframe */ if(sub->type == FLAC_SUBFRAME_CONSTANT) { output_subframe_constant(s, ch); } else if(sub->type == FLAC_SUBFRAME_VERBATIM) { output_subframe_verbatim(s, ch); } else if(sub->type == FLAC_SUBFRAME_FIXED) { output_subframe_fixed(s, ch); } else if(sub->type == FLAC_SUBFRAME_LPC) { output_subframe_lpc(s, ch); } } } static void output_frame_footer(FlacEncodeContext *s) { int crc; flush_put_bits(&s->pb); crc = bswap_16(av_crc(av_crc8005, 0, s->pb.buf, put_bits_count(&s->pb)>>3)); put_bits(&s->pb, 16, crc); flush_put_bits(&s->pb); } static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame, int buf_size, void *data) { int ch; FlacEncodeContext *s; int16_t *samples = data; int out_bytes; s = avctx->priv_data; s->blocksize = avctx->frame_size; init_frame(s); copy_samples(s, samples); channel_decorrelation(s); for(ch=0; chchannels; ch++) { encode_residual(s, ch); } init_put_bits(&s->pb, frame, buf_size); output_frame_header(s); output_subframes(s); output_frame_footer(s); out_bytes = put_bits_count(&s->pb) >> 3; if(out_bytes > s->max_framesize || out_bytes >= buf_size) { /* frame too large. use verbatim mode */ for(ch=0; chchannels; ch++) { encode_residual_v(s, ch); } init_put_bits(&s->pb, frame, buf_size); output_frame_header(s); output_subframes(s); output_frame_footer(s); out_bytes = put_bits_count(&s->pb) >> 3; if(out_bytes > s->max_framesize || out_bytes >= buf_size) { /* still too large. must be an error. */ av_log(avctx, AV_LOG_ERROR, "error encoding frame\n"); return -1; } } s->frame_count++; return out_bytes; } static int flac_encode_close(AVCodecContext *avctx) { av_freep(&avctx->extradata); avctx->extradata_size = 0; av_freep(&avctx->coded_frame); return 0; } AVCodec flac_encoder = { "flac", CODEC_TYPE_AUDIO, CODEC_ID_FLAC, sizeof(FlacEncodeContext), flac_encode_init, flac_encode_frame, flac_encode_close, NULL, .capabilities = CODEC_CAP_SMALL_LAST_FRAME, };