3 * Copyright (c) 2006 Justin Ruggles <jruggle@earthlink.net>
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 #include "bitstream.h"
26 #define FLAC_MIN_BLOCKSIZE 16
27 #define FLAC_MAX_BLOCKSIZE 65535
29 #define FLAC_SUBFRAME_CONSTANT 0
30 #define FLAC_SUBFRAME_VERBATIM 1
31 #define FLAC_SUBFRAME_FIXED 8
32 #define FLAC_SUBFRAME_LPC 32
34 #define FLAC_CHMODE_NOT_STEREO 0
35 #define FLAC_CHMODE_LEFT_RIGHT 1
36 #define FLAC_CHMODE_LEFT_SIDE 8
37 #define FLAC_CHMODE_RIGHT_SIDE 9
38 #define FLAC_CHMODE_MID_SIDE 10
40 #define FLAC_STREAMINFO_SIZE 34
42 typedef struct RiceContext {
47 typedef struct FlacSubframe {
53 int32_t samples[FLAC_MAX_BLOCKSIZE];
54 int32_t residual[FLAC_MAX_BLOCKSIZE];
57 typedef struct FlacFrame {
58 FlacSubframe subframes[FLAC_MAX_CH];
65 typedef struct FlacEncodeContext {
75 AVCodecContext *avctx;
78 static const int flac_samplerates[16] = {
80 8000, 16000, 22050, 24000, 32000, 44100, 48000, 96000,
84 static const int flac_blocksizes[16] = {
87 576, 1152, 2304, 4608,
89 256, 512, 1024, 2048, 4096, 8192, 16384, 32768
93 * Writes streaminfo metadata block to byte array
95 static void write_streaminfo(FlacEncodeContext *s, uint8_t *header)
99 memset(header, 0, FLAC_STREAMINFO_SIZE);
100 init_put_bits(&pb, header, FLAC_STREAMINFO_SIZE);
102 /* streaminfo metadata block */
103 put_bits(&pb, 16, s->blocksize);
104 put_bits(&pb, 16, s->blocksize);
105 put_bits(&pb, 24, 0);
106 put_bits(&pb, 24, s->max_framesize);
107 put_bits(&pb, 20, s->samplerate);
108 put_bits(&pb, 3, s->channels-1);
109 put_bits(&pb, 5, 15); /* bits per sample - 1 */
111 /* total samples = 0 */
112 /* MD5 signature = 0 */
115 #define BLOCK_TIME_MS 27
118 * Sets blocksize based on samplerate
119 * Chooses the closest predefined blocksize >= BLOCK_TIME_MS milliseconds
121 static int select_blocksize(int samplerate)
127 assert(samplerate > 0);
128 blocksize = flac_blocksizes[1];
129 target = (samplerate * BLOCK_TIME_MS) / 1000;
130 for(i=0; i<16; i++) {
131 if(target >= flac_blocksizes[i] && flac_blocksizes[i] > blocksize) {
132 blocksize = flac_blocksizes[i];
138 static int flac_encode_init(AVCodecContext *avctx)
140 int freq = avctx->sample_rate;
141 int channels = avctx->channels;
142 FlacEncodeContext *s = avctx->priv_data;
148 if(avctx->sample_fmt != SAMPLE_FMT_S16) {
152 if(channels < 1 || channels > FLAC_MAX_CH) {
155 s->channels = channels;
156 s->ch_code = s->channels-1;
158 /* find samplerate in table */
161 for(i=4; i<12; i++) {
162 if(freq == flac_samplerates[i]) {
163 s->samplerate = flac_samplerates[i];
169 /* if not in table, samplerate is non-standard */
171 if(freq % 1000 == 0 && freq < 255000) {
173 s->sr_code[1] = freq / 1000;
174 } else if(freq % 10 == 0 && freq < 655350) {
176 s->sr_code[1] = freq / 10;
177 } else if(freq < 65535) {
179 s->sr_code[1] = freq;
183 s->samplerate = freq;
186 s->blocksize = select_blocksize(s->samplerate);
187 avctx->frame_size = s->blocksize;
189 /* set maximum encoded frame size in verbatim mode */
190 if(s->channels == 2) {
191 s->max_framesize = 14 + ((s->blocksize * 33 + 7) >> 3);
193 s->max_framesize = 14 + (s->blocksize * s->channels * 2);
196 streaminfo = av_malloc(FLAC_STREAMINFO_SIZE);
197 write_streaminfo(s, streaminfo);
198 avctx->extradata = streaminfo;
199 avctx->extradata_size = FLAC_STREAMINFO_SIZE;
203 avctx->coded_frame = avcodec_alloc_frame();
204 avctx->coded_frame->key_frame = 1;
209 static void init_frame(FlacEncodeContext *s)
216 for(i=0; i<16; i++) {
217 if(s->blocksize == flac_blocksizes[i]) {
218 frame->blocksize = flac_blocksizes[i];
219 frame->bs_code[0] = i;
220 frame->bs_code[1] = 0;
225 frame->blocksize = s->blocksize;
226 if(frame->blocksize <= 256) {
227 frame->bs_code[0] = 6;
228 frame->bs_code[1] = frame->blocksize-1;
230 frame->bs_code[0] = 7;
231 frame->bs_code[1] = frame->blocksize-1;
235 for(ch=0; ch<s->channels; ch++) {
236 frame->subframes[ch].obits = 16;
241 * Copy channel-interleaved input samples into separate subframes
243 static void copy_samples(FlacEncodeContext *s, int16_t *samples)
249 for(i=0,j=0; i<frame->blocksize; i++) {
250 for(ch=0; ch<s->channels; ch++,j++) {
251 frame->subframes[ch].samples[i] = samples[j];
257 #define rice_encode_count(sum, n, k) (((n)*((k)+1))+((sum-(n>>1))>>(k)))
259 static int find_optimal_param(uint32_t sum, int n)
262 uint32_t nbits, nbits_opt;
265 nbits_opt = rice_encode_count(sum, n, 0);
266 for(k=1; k<=14; k++) {
267 nbits = rice_encode_count(sum, n, k);
268 if(nbits < nbits_opt) {
276 static uint32_t calc_optimal_rice_params(RiceContext *rc, int porder,
277 uint32_t *sums, int n, int pred_order)
283 part = (1 << porder);
286 cnt = (n >> porder) - pred_order;
287 for(i=0; i<part; i++) {
288 if(i == 1) cnt = (n >> porder);
289 k = find_optimal_param(sums[i], cnt);
291 all_bits += rice_encode_count(sums[i], cnt, k);
293 all_bits += (4 * part);
300 static void calc_sums(int pmax, uint32_t *data, int n, int pred_order,
301 uint32_t sums[][256])
307 /* sums for highest level */
309 res = &data[pred_order];
310 cnt = (n >> pmax) - pred_order;
311 for(i=0; i<parts; i++) {
312 if(i == 1) cnt = (n >> pmax);
313 if(i > 0) res = &data[i*cnt];
315 for(j=0; j<cnt; j++) {
316 sums[pmax][i] += res[j];
319 /* sums for lower levels */
320 for(i=pmax-1; i>=0; i--) {
322 for(j=0; j<parts; j++) {
323 sums[i][j] = sums[i+1][2*j] + sums[i+1][2*j+1];
328 static uint32_t calc_rice_params(RiceContext *rc, int pmax, int32_t *data,
329 int n, int pred_order)
332 uint32_t bits, opt_bits;
336 uint32_t sums[9][256];
338 assert(pmax >= 0 && pmax <= 8);
340 udata = av_malloc(n * sizeof(uint32_t));
342 udata[i] = (2*data[i]) ^ (data[i]>>31);
345 calc_sums(pmax, udata, n, pred_order, sums);
348 opt_bits = UINT32_MAX;
349 for(i=0; i<=pmax; i++) {
350 bits = calc_optimal_rice_params(rc, i, sums[i], n, pred_order);
351 if(bits < opt_bits) {
354 memcpy(&opt_rc, rc, sizeof(RiceContext));
357 if(opt_porder != pmax) {
358 memcpy(rc, &opt_rc, sizeof(RiceContext));
365 static uint32_t calc_rice_params_fixed(RiceContext *rc, int pmax, int32_t *data,
366 int n, int pred_order, int bps)
369 bits = pred_order*bps + 6;
370 bits += calc_rice_params(rc, pmax, data, n, pred_order);
374 static void encode_residual_verbatim(int32_t *res, int32_t *smp, int n)
377 memcpy(res, smp, n * sizeof(int32_t));
380 static void encode_residual_fixed(int32_t *res, int32_t *smp, int n, int order)
384 for(i=0; i<order; i++) {
389 for(i=order; i<n; i++)
392 for(i=order; i<n; i++)
393 res[i]= smp[i] - smp[i-1];
395 for(i=order; i<n; i++)
396 res[i]= smp[i] - 2*smp[i-1] + smp[i-2];
398 for(i=order; i<n; i++)
399 res[i]= smp[i] - 3*smp[i-1] + 3*smp[i-2] - smp[i-3];
401 for(i=order; i<n; i++)
402 res[i]= smp[i] - 4*smp[i-1] + 6*smp[i-2] - 4*smp[i-3] + smp[i-4];
406 static int get_max_p_order(int max_porder, int n, int order)
408 int porder, max_parts;
412 max_parts = (1 << porder);
413 if(!(n % max_parts) && (n > max_parts*order)) {
421 static int encode_residual(FlacEncodeContext *ctx, int ch)
423 int i, opt_order, porder, max_porder, n;
430 sub = &frame->subframes[ch];
433 n = frame->blocksize;
437 if(smp[i] != smp[0]) break;
440 sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
447 sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
448 encode_residual_verbatim(res, smp, n);
449 return sub->obits * n;
456 bits[0] = UINT32_MAX;
457 for(i=0; i<=4; i++) {
458 encode_residual_fixed(res, smp, n, i);
459 porder = get_max_p_order(max_porder, n, i);
460 bits[i] = calc_rice_params_fixed(&sub->rc, porder, res, n, i, sub->obits);
461 if(bits[i] < bits[opt_order]) {
465 sub->order = opt_order;
466 sub->type = FLAC_SUBFRAME_FIXED;
467 sub->type_code = sub->type | sub->order;
468 if(sub->order != 4) {
469 encode_residual_fixed(res, smp, n, sub->order);
470 porder = get_max_p_order(max_porder, n, sub->order);
471 calc_rice_params_fixed(&sub->rc, porder, res, n, sub->order, sub->obits);
473 return bits[sub->order];
476 static int encode_residual_v(FlacEncodeContext *ctx, int ch)
484 sub = &frame->subframes[ch];
487 n = frame->blocksize;
491 if(smp[i] != smp[0]) break;
494 sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
500 sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
501 encode_residual_verbatim(res, smp, n);
502 return sub->obits * n;
505 static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
513 /* calculate sum of squares for each channel */
514 sum[0] = sum[1] = sum[2] = sum[3] = 0;
516 lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
517 rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
518 sum[2] += ABS((lt + rt) >> 1);
519 sum[3] += ABS(lt - rt);
524 k = find_optimal_param(2*sum[i], n);
525 sum[i] = rice_encode_count(2*sum[i], n, k);
528 /* calculate score for each mode */
529 score[0] = sum[0] + sum[1];
530 score[1] = sum[0] + sum[3];
531 score[2] = sum[1] + sum[3];
532 score[3] = sum[2] + sum[3];
534 /* return mode with lowest score */
537 if(score[i] < score[best]) {
542 return FLAC_CHMODE_LEFT_RIGHT;
543 } else if(best == 1) {
544 return FLAC_CHMODE_LEFT_SIDE;
545 } else if(best == 2) {
546 return FLAC_CHMODE_RIGHT_SIDE;
548 return FLAC_CHMODE_MID_SIDE;
553 * Perform stereo channel decorrelation
555 static void channel_decorrelation(FlacEncodeContext *ctx)
558 int32_t *left, *right;
562 n = frame->blocksize;
563 left = frame->subframes[0].samples;
564 right = frame->subframes[1].samples;
566 if(ctx->channels != 2) {
567 frame->ch_mode = FLAC_CHMODE_NOT_STEREO;
571 frame->ch_mode = estimate_stereo_mode(left, right, n);
573 /* perform decorrelation and adjust bits-per-sample */
574 if(frame->ch_mode == FLAC_CHMODE_LEFT_RIGHT) {
577 if(frame->ch_mode == FLAC_CHMODE_MID_SIDE) {
581 left[i] = (tmp + right[i]) >> 1;
582 right[i] = tmp - right[i];
584 frame->subframes[1].obits++;
585 } else if(frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
587 right[i] = left[i] - right[i];
589 frame->subframes[1].obits++;
594 frame->subframes[0].obits++;
598 static void put_sbits(PutBitContext *pb, int bits, int32_t val)
600 assert(bits >= 0 && bits <= 31);
602 put_bits(pb, bits, val & ((1<<bits)-1));
605 static void write_utf8(PutBitContext *pb, uint32_t val)
610 put_bits(pb, 8, val);
614 bytes= (av_log2(val)+4) / 5;
615 shift = (bytes - 1) * 6;
616 put_bits(pb, 8, (256 - (256>>bytes)) | (val >> shift));
619 put_bits(pb, 8, 0x80 | ((val >> shift) & 0x3F));
623 static void output_frame_header(FlacEncodeContext *s)
630 put_bits(&s->pb, 16, 0xFFF8);
631 put_bits(&s->pb, 4, frame->bs_code[0]);
632 put_bits(&s->pb, 4, s->sr_code[0]);
633 if(frame->ch_mode == FLAC_CHMODE_NOT_STEREO) {
634 put_bits(&s->pb, 4, s->ch_code);
636 put_bits(&s->pb, 4, frame->ch_mode);
638 put_bits(&s->pb, 3, 4); /* bits-per-sample code */
639 put_bits(&s->pb, 1, 0);
640 write_utf8(&s->pb, s->frame_count);
641 if(frame->bs_code[0] == 6) {
642 put_bits(&s->pb, 8, frame->bs_code[1]);
643 } else if(frame->bs_code[0] == 7) {
644 put_bits(&s->pb, 16, frame->bs_code[1]);
646 if(s->sr_code[0] == 12) {
647 put_bits(&s->pb, 8, s->sr_code[1]);
648 } else if(s->sr_code[0] > 12) {
649 put_bits(&s->pb, 16, s->sr_code[1]);
651 flush_put_bits(&s->pb);
652 crc = av_crc(av_crc07, 0, s->pb.buf, put_bits_count(&s->pb)>>3);
653 put_bits(&s->pb, 8, crc);
656 static void output_subframe_constant(FlacEncodeContext *s, int ch)
661 sub = &s->frame.subframes[ch];
662 res = sub->residual[0];
663 put_sbits(&s->pb, sub->obits, res);
666 static void output_subframe_verbatim(FlacEncodeContext *s, int ch)
674 sub = &frame->subframes[ch];
676 for(i=0; i<frame->blocksize; i++) {
677 res = sub->residual[i];
678 put_sbits(&s->pb, sub->obits, res);
682 static void output_residual(FlacEncodeContext *ctx, int ch)
684 int i, j, p, n, parts;
685 int k, porder, psize, res_cnt;
691 sub = &frame->subframes[ch];
693 n = frame->blocksize;
695 /* rice-encoded block */
696 put_bits(&ctx->pb, 2, 0);
698 /* partition order */
699 porder = sub->rc.porder;
701 parts = (1 << porder);
702 put_bits(&ctx->pb, 4, porder);
703 res_cnt = psize - sub->order;
707 for(p=0; p<parts; p++) {
708 k = sub->rc.params[p];
709 put_bits(&ctx->pb, 4, k);
710 if(p == 1) res_cnt = psize;
711 for(i=0; i<res_cnt && j<n; i++, j++) {
712 set_sr_golomb_flac(&ctx->pb, res[j], k, INT32_MAX, 0);
717 static void output_subframe_fixed(FlacEncodeContext *ctx, int ch)
724 sub = &frame->subframes[ch];
726 /* warm-up samples */
727 for(i=0; i<sub->order; i++) {
728 put_sbits(&ctx->pb, sub->obits, sub->residual[i]);
732 output_residual(ctx, ch);
735 static void output_subframes(FlacEncodeContext *s)
743 for(ch=0; ch<s->channels; ch++) {
744 sub = &frame->subframes[ch];
746 /* subframe header */
747 put_bits(&s->pb, 1, 0);
748 put_bits(&s->pb, 6, sub->type_code);
749 put_bits(&s->pb, 1, 0); /* no wasted bits */
752 if(sub->type == FLAC_SUBFRAME_CONSTANT) {
753 output_subframe_constant(s, ch);
754 } else if(sub->type == FLAC_SUBFRAME_VERBATIM) {
755 output_subframe_verbatim(s, ch);
756 } else if(sub->type == FLAC_SUBFRAME_FIXED) {
757 output_subframe_fixed(s, ch);
762 static void output_frame_footer(FlacEncodeContext *s)
765 flush_put_bits(&s->pb);
766 crc = bswap_16(av_crc(av_crc8005, 0, s->pb.buf, put_bits_count(&s->pb)>>3));
767 put_bits(&s->pb, 16, crc);
768 flush_put_bits(&s->pb);
771 static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
772 int buf_size, void *data)
775 FlacEncodeContext *s;
776 int16_t *samples = data;
779 s = avctx->priv_data;
781 s->blocksize = avctx->frame_size;
784 copy_samples(s, samples);
786 channel_decorrelation(s);
788 for(ch=0; ch<s->channels; ch++) {
789 encode_residual(s, ch);
791 init_put_bits(&s->pb, frame, buf_size);
792 output_frame_header(s);
794 output_frame_footer(s);
795 out_bytes = put_bits_count(&s->pb) >> 3;
797 if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
798 /* frame too large. use verbatim mode */
799 for(ch=0; ch<s->channels; ch++) {
800 encode_residual_v(s, ch);
802 init_put_bits(&s->pb, frame, buf_size);
803 output_frame_header(s);
805 output_frame_footer(s);
806 out_bytes = put_bits_count(&s->pb) >> 3;
808 if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
809 /* still too large. must be an error. */
810 av_log(avctx, AV_LOG_ERROR, "error encoding frame\n");
819 static int flac_encode_close(AVCodecContext *avctx)
821 av_freep(&avctx->extradata);
822 avctx->extradata_size = 0;
823 av_freep(&avctx->coded_frame);
827 AVCodec flac_encoder = {
831 sizeof(FlacEncodeContext),
836 .capabilities = CODEC_CAP_SMALL_LAST_FRAME,