/** * FLAC audio encoder * Copyright (c) 2006 Justin Ruggles * * This library 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 of the License, or (at your option) any later version. * * This library 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 this library; 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" #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 FLAC_STREAMINFO_SIZE 34 typedef struct RiceContext { int porder; int params[256]; } RiceContext; typedef struct FlacSubframe { int type; int type_code; int obits; int order; 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; 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 */ } #define BLOCK_TIME_MS 27 /** * Sets blocksize based on samplerate * Chooses the closest predefined blocksize >= BLOCK_TIME_MS milliseconds */ static int select_blocksize(int samplerate) { 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; 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; } s->blocksize = select_blocksize(s->samplerate); avctx->frame_size = s->blocksize; /* 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, nbits_opt; k_opt = 0; nbits_opt = rice_encode_count(sum, n, 0); for(k=1; k<=14; k++) { nbits = rice_encode_count(sum, n, k); if(nbits < nbits_opt) { nbits_opt = nbits; 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 pmax, uint32_t *data, int n, int pred_order, uint32_t sums[][256]) { 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>=0; i--) { parts = (1 << i); for(j=0; j= 0 && pmax <= 8); udata = av_malloc(n * sizeof(uint32_t)); for(i=0; i>31); } calc_sums(pmax, udata, n, pred_order, sums); opt_porder = 0; opt_bits = UINT32_MAX; for(i=0; i<=pmax; i++) { bits = calc_optimal_rice_params(rc, i, sums[i], n, pred_order); if(bits < opt_bits) { opt_bits = bits; opt_porder = i; memcpy(&opt_rc, rc, sizeof(RiceContext)); } } if(opt_porder != pmax) { memcpy(rc, &opt_rc, sizeof(RiceContext)); } av_freep(&udata); return opt_bits; } static uint32_t calc_rice_params_fixed(RiceContext *rc, int pmax, int32_t *data, int n, int pred_order, int bps) { uint32_t bits; bits = pred_order*bps + 6; bits += calc_rice_params(rc, pmax, data, n, pred_order); return bits; } static void encode_residual_verbatim(int32_t *res, int32_t *smp, int n) { assert(n > 0); memcpy(res, smp, n * sizeof(int32_t)); } static void encode_residual_fixed(int32_t *res, int32_t *smp, int n, int order) { int i; for(i=0; i 0) { max_parts = (1 << porder); if(!(n % max_parts) && (n > max_parts*order)) { break; } porder--; } return porder; } static int encode_residual(FlacEncodeContext *ctx, int ch) { int i, opt_order, porder, max_porder, n; FlacFrame *frame; FlacSubframe *sub; uint32_t bits[5]; 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; } max_porder = 3; /* FIXED */ opt_order = 0; bits[0] = UINT32_MAX; for(i=0; i<=4; i++) { encode_residual_fixed(res, smp, n, i); porder = get_max_p_order(max_porder, n, i); bits[i] = calc_rice_params_fixed(&sub->rc, 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 != 4) { encode_residual_fixed(res, smp, n, sub->order); porder = get_max_p_order(max_porder, n, sub->order); calc_rice_params_fixed(&sub->rc, porder, res, n, sub->order, sub->obits); } return bits[sub->order]; } 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 squares for each channel */ sum[0] = sum[1] = sum[2] = sum[3] = 0; for(i=2; i> 1); sum[3] += ABS(lt - rt); sum[0] += ABS(lt); sum[1] += ABS(rt); } 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<>bytes)) | (val >> shift)); while(shift >= 6){ shift -= 6; put_bits(pb, 8, 0x80 | ((val >> shift) & 0x3F)); } } static void output_frame_header(FlacEncodeContext *s) { FlacFrame *frame; int crc; frame = &s->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_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); } } } 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, };