aboutsummaryrefslogtreecommitdiffstats
path: root/fftools/sync_queue.c
blob: bc107ba4fe75d6f1b9655e7d9ddf59c85b2032a1 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
/*
 * 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 <stdint.h>
#include <string.h>

#include "libavutil/avassert.h"
#include "libavutil/channel_layout.h"
#include "libavutil/cpu.h"
#include "libavutil/error.h"
#include "libavutil/fifo.h"
#include "libavutil/mathematics.h"
#include "libavutil/mem.h"
#include "libavutil/samplefmt.h"
#include "libavutil/timestamp.h"

#include "objpool.h"
#include "sync_queue.h"

/*
 * How this works:
 * --------------
 * time:   0    1    2    3    4    5    6    7    8    9    10   11   12   13
 *         -------------------------------------------------------------------
 *         |    |    |    |    |    |    |    |    |    |    |    |    |    |
 *         |    ┌───┐┌────────┐┌───┐┌─────────────┐
 * stream 0|    │d=1││  d=2   ││d=1││    d=3      │
 *         |    └───┘└────────┘└───┘└─────────────┘
 *         ┌───┐               ┌───────────────────────┐
 * stream 1│d=1│               │         d=5           │
 *         └───┘               └───────────────────────┘
 *         |    ┌───┐┌───┐┌───┐┌───┐
 * stream 2|    │d=1││d=1││d=1││d=1│ <- stream 2 is the head stream of the queue
 *         |    └───┘└───┘└───┘└───┘
 *                  ^              ^
 *          [stream 2 tail] [stream 2 head]
 *
 * We have N streams (N=3 in the diagram), each stream is a FIFO. The *tail* of
 * each FIFO is the frame with smallest end time, the *head* is the frame with
 * the largest end time. Frames submitted to the queue with sq_send() are placed
 * after the head, frames returned to the caller with sq_receive() are taken
 * from the tail.
 *
 * The head stream of the whole queue (SyncQueue.head_stream) is the limiting
 * stream with the *smallest* head timestamp, i.e. the stream whose source lags
 * furthest behind all other streams. It determines which frames can be output
 * from the queue.
 *
 * In the diagram, the head stream is 2, because it head time is t=5, while
 * streams 0 and 1 end at t=8 and t=9 respectively. All frames that _end_ at
 * or before t=5 can be output, i.e. the first 3 frames from stream 0, first
 * frame from stream 1, and all 4 frames from stream 2.
 */

typedef struct SyncQueueStream {
    AVFifo          *fifo;
    AVRational       tb;

    /* number of audio samples in fifo */
    uint64_t         samples_queued;
    /* stream head: largest timestamp seen */
    int64_t          head_ts;
    int              limiting;
    /* no more frames will be sent for this stream */
    int              finished;

    uint64_t         frames_sent;
    uint64_t         samples_sent;
    uint64_t         frames_max;
    int              frame_samples;
} SyncQueueStream;

struct SyncQueue {
    enum SyncQueueType type;

    void *logctx;

    /* no more frames will be sent for any stream */
    int finished;
    /* sync head: the stream with the _smallest_ head timestamp
     * this stream determines which frames can be output */
    int head_stream;
    /* the finished stream with the smallest finish timestamp or -1 */
    int head_finished_stream;

    // maximum buffering duration in microseconds
    int64_t buf_size_us;

    SyncQueueStream *streams;
    unsigned int  nb_streams;

    // pool of preallocated frames to avoid constant allocations
    ObjPool *pool;

    int have_limiting;

    uintptr_t align_mask;
};

static void frame_move(const SyncQueue *sq, SyncQueueFrame dst,
                       SyncQueueFrame src)
{
    if (sq->type == SYNC_QUEUE_PACKETS)
        av_packet_move_ref(dst.p, src.p);
    else
        av_frame_move_ref(dst.f, src.f);
}

/**
 * Compute the end timestamp of a frame. If nb_samples is provided, consider
 * the frame to have this number of audio samples, otherwise use frame duration.
 */
static int64_t frame_end(const SyncQueue *sq, SyncQueueFrame frame, int nb_samples)
{
    if (nb_samples) {
        int64_t d = av_rescale_q(nb_samples, (AVRational){ 1, frame.f->sample_rate},
                                 frame.f->time_base);
        return frame.f->pts + d;
    }

    return (sq->type == SYNC_QUEUE_PACKETS) ?
           frame.p->pts + frame.p->duration :
           frame.f->pts + frame.f->duration;
}

static int frame_samples(const SyncQueue *sq, SyncQueueFrame frame)
{
    return (sq->type == SYNC_QUEUE_PACKETS) ? 0 : frame.f->nb_samples;
}

static int frame_null(const SyncQueue *sq, SyncQueueFrame frame)
{
    return (sq->type == SYNC_QUEUE_PACKETS) ? (frame.p == NULL) : (frame.f == NULL);
}

static void tb_update(const SyncQueue *sq, SyncQueueStream *st,
                      const SyncQueueFrame frame)
{
    AVRational tb = (sq->type == SYNC_QUEUE_PACKETS) ?
                    frame.p->time_base : frame.f->time_base;

    av_assert0(tb.num > 0 && tb.den > 0);

    if (tb.num == st->tb.num && tb.den == st->tb.den)
        return;

    // timebase should not change after the first frame
    av_assert0(!av_fifo_can_read(st->fifo));

    if (st->head_ts != AV_NOPTS_VALUE)
        st->head_ts = av_rescale_q(st->head_ts, st->tb, tb);

    st->tb = tb;
}

static void finish_stream(SyncQueue *sq, unsigned int stream_idx)
{
    SyncQueueStream *st = &sq->streams[stream_idx];

    if (!st->finished)
        av_log(sq->logctx, AV_LOG_DEBUG,
               "sq: finish %u; head ts %s\n", stream_idx,
               av_ts2timestr(st->head_ts, &st->tb));

    st->finished = 1;

    if (st->limiting && st->head_ts != AV_NOPTS_VALUE) {
        /* check if this stream is the new finished head */
        if (sq->head_finished_stream < 0 ||
            av_compare_ts(st->head_ts, st->tb,
                          sq->streams[sq->head_finished_stream].head_ts,
                          sq->streams[sq->head_finished_stream].tb) < 0) {
            sq->head_finished_stream = stream_idx;
        }

        /* mark as finished all streams that should no longer receive new frames,
         * due to them being ahead of some finished stream */
        st = &sq->streams[sq->head_finished_stream];
        for (unsigned int i = 0; i < sq->nb_streams; i++) {
            SyncQueueStream *st1 = &sq->streams[i];
            if (st != st1 && st1->head_ts != AV_NOPTS_VALUE &&
                av_compare_ts(st->head_ts, st->tb, st1->head_ts, st1->tb) <= 0) {
                if (!st1->finished)
                    av_log(sq->logctx, AV_LOG_DEBUG,
                           "sq: finish secondary %u; head ts %s\n", i,
                           av_ts2timestr(st1->head_ts, &st1->tb));

                st1->finished = 1;
            }
        }
    }

    /* mark the whole queue as finished if all streams are finished */
    for (unsigned int i = 0; i < sq->nb_streams; i++) {
        if (!sq->streams[i].finished)
            return;
    }
    sq->finished = 1;

    av_log(sq->logctx, AV_LOG_DEBUG, "sq: finish queue\n");
}

static void queue_head_update(SyncQueue *sq)
{
    av_assert0(sq->have_limiting);

    if (sq->head_stream < 0) {
        unsigned first_limiting = UINT_MAX;

        /* wait for one timestamp in each stream before determining
         * the queue head */
        for (unsigned int i = 0; i < sq->nb_streams; i++) {
            SyncQueueStream *st = &sq->streams[i];
            if (!st->limiting)
                continue;
            if (st->head_ts == AV_NOPTS_VALUE)
                return;
            if (first_limiting == UINT_MAX)
                first_limiting = i;
        }

        // placeholder value, correct one will be found below
        av_assert0(first_limiting < UINT_MAX);
        sq->head_stream = first_limiting;
    }

    for (unsigned int i = 0; i < sq->nb_streams; i++) {
        SyncQueueStream *st_head  = &sq->streams[sq->head_stream];
        SyncQueueStream *st_other = &sq->streams[i];
        if (st_other->limiting && st_other->head_ts != AV_NOPTS_VALUE &&
            av_compare_ts(st_other->head_ts, st_other->tb,
                          st_head->head_ts,  st_head->tb) < 0)
            sq->head_stream = i;
    }
}

/* update this stream's head timestamp */
static void stream_update_ts(SyncQueue *sq, unsigned int stream_idx, int64_t ts)
{
    SyncQueueStream *st = &sq->streams[stream_idx];

    if (ts == AV_NOPTS_VALUE ||
        (st->head_ts != AV_NOPTS_VALUE && st->head_ts >= ts))
        return;

    st->head_ts = ts;

    /* if this stream is now ahead of some finished stream, then
     * this stream is also finished */
    if (sq->head_finished_stream >= 0 &&
        av_compare_ts(sq->streams[sq->head_finished_stream].head_ts,
                      sq->streams[sq->head_finished_stream].tb,
                      ts, st->tb) <= 0)
        finish_stream(sq, stream_idx);

    /* update the overall head timestamp if it could have changed */
    if (st->limiting &&
        (sq->head_stream < 0 || sq->head_stream == stream_idx))
        queue_head_update(sq);
}

/* If the queue for the given stream (or all streams when stream_idx=-1)
 * is overflowing, trigger a fake heartbeat on lagging streams.
 *
 * @return 1 if heartbeat triggered, 0 otherwise
 */
static int overflow_heartbeat(SyncQueue *sq, int stream_idx)
{
    SyncQueueStream *st;
    SyncQueueFrame frame;
    int64_t tail_ts = AV_NOPTS_VALUE;

    /* if no stream specified, pick the one that is most ahead */
    if (stream_idx < 0) {
        int64_t ts = AV_NOPTS_VALUE;

        for (int i = 0; i < sq->nb_streams; i++) {
            st = &sq->streams[i];
            if (st->head_ts != AV_NOPTS_VALUE &&
                (ts == AV_NOPTS_VALUE ||
                 av_compare_ts(ts, sq->streams[stream_idx].tb,
                               st->head_ts, st->tb) < 0)) {
                ts = st->head_ts;
                stream_idx = i;
            }
        }
        /* no stream has a timestamp yet -> nothing to do */
        if (stream_idx < 0)
            return 0;
    }

    st = &sq->streams[stream_idx];

    /* get the chosen stream's tail timestamp */
    for (size_t i = 0; tail_ts == AV_NOPTS_VALUE &&
                       av_fifo_peek(st->fifo, &frame, 1, i) >= 0; i++)
        tail_ts = frame_end(sq, frame, 0);

    /* overflow triggers when the tail is over specified duration behind the head */
    if (tail_ts == AV_NOPTS_VALUE || tail_ts >= st->head_ts ||
        av_rescale_q(st->head_ts - tail_ts, st->tb, AV_TIME_BASE_Q) < sq->buf_size_us)
        return 0;

    /* signal a fake timestamp for all streams that prevent tail_ts from being output */
    tail_ts++;
    for (unsigned int i = 0; i < sq->nb_streams; i++) {
        SyncQueueStream *st1 = &sq->streams[i];
        int64_t ts;

        if (st == st1 || st1->finished ||
            (st1->head_ts != AV_NOPTS_VALUE &&
             av_compare_ts(tail_ts, st->tb, st1->head_ts, st1->tb) <= 0))
            continue;

        ts = av_rescale_q(tail_ts, st->tb, st1->tb);
        if (st1->head_ts != AV_NOPTS_VALUE)
            ts = FFMAX(st1->head_ts + 1, ts);

        av_log(sq->logctx, AV_LOG_DEBUG, "sq: %u overflow heardbeat %s -> %s\n",
               i, av_ts2timestr(st1->head_ts, &st1->tb), av_ts2timestr(ts, &st1->tb));

        stream_update_ts(sq, i, ts);
    }

    return 1;
}

int sq_send(SyncQueue *sq, unsigned int stream_idx, SyncQueueFrame frame)
{
    SyncQueueStream *st;
    SyncQueueFrame dst;
    int64_t ts;
    int ret, nb_samples;

    av_assert0(stream_idx < sq->nb_streams);
    st = &sq->streams[stream_idx];

    if (frame_null(sq, frame)) {
        av_log(sq->logctx, AV_LOG_DEBUG, "sq: %u EOF\n", stream_idx);
        finish_stream(sq, stream_idx);
        return 0;
    }
    if (st->finished)
        return AVERROR_EOF;

    tb_update(sq, st, frame);

    ret = objpool_get(sq->pool, (void**)&dst);
    if (ret < 0)
        return ret;

    frame_move(sq, dst, frame);

    nb_samples = frame_samples(sq, dst);
    // make sure frame duration is consistent with sample count
    if (nb_samples) {
        av_assert0(dst.f->sample_rate > 0);
        dst.f->duration = av_rescale_q(nb_samples, (AVRational){ 1, dst.f->sample_rate },
                                       dst.f->time_base);
    }

    ts = frame_end(sq, dst, 0);

    av_log(sq->logctx, AV_LOG_DEBUG, "sq: send %u ts %s\n", stream_idx,
           av_ts2timestr(ts, &st->tb));

    ret = av_fifo_write(st->fifo, &dst, 1);
    if (ret < 0) {
        frame_move(sq, frame, dst);
        objpool_release(sq->pool, (void**)&dst);
        return ret;
    }

    stream_update_ts(sq, stream_idx, ts);

    st->samples_queued += nb_samples;
    st->samples_sent   += nb_samples;

    if (st->frame_samples)
        st->frames_sent = st->samples_sent / st->frame_samples;
    else
        st->frames_sent++;

    if (st->frames_sent >= st->frames_max) {
        av_log(sq->logctx, AV_LOG_DEBUG, "sq: %u frames_max %"PRIu64" reached\n",
               stream_idx, st->frames_max);

        finish_stream(sq, stream_idx);
    }

    return 0;
}

static void offset_audio(AVFrame *f, int nb_samples)
{
    const int planar = av_sample_fmt_is_planar(f->format);
    const int planes = planar ? f->ch_layout.nb_channels : 1;
    const int    bps = av_get_bytes_per_sample(f->format);
    const int offset = nb_samples * bps * (planar ? 1 : f->ch_layout.nb_channels);

    av_assert0(bps > 0);
    av_assert0(nb_samples < f->nb_samples);

    for (int i = 0; i < planes; i++) {
        f->extended_data[i] += offset;
        if (i < FF_ARRAY_ELEMS(f->data))
            f->data[i] = f->extended_data[i];
    }
    f->linesize[0] -= offset;
    f->nb_samples  -= nb_samples;
    f->duration     = av_rescale_q(f->nb_samples, (AVRational){ 1, f->sample_rate },
                                   f->time_base);
    f->pts         += av_rescale_q(nb_samples,    (AVRational){ 1, f->sample_rate },
                                   f->time_base);
}

static int frame_is_aligned(const SyncQueue *sq, const AVFrame *frame)
{
    // only checks linesize[0], so only works for audio
    av_assert0(frame->nb_samples > 0);
    av_assert0(sq->align_mask);

    // only check data[0], because we always offset all data pointers
    // by the same offset, so if one is aligned, all are
    if (!((uintptr_t)frame->data[0] & sq->align_mask) &&
        !(frame->linesize[0]        & sq->align_mask) &&
        frame->linesize[0] > sq->align_mask)
        return 1;

    return 0;
}

static int receive_samples(SyncQueue *sq, SyncQueueStream *st,
                           AVFrame *dst, int nb_samples)
{
    SyncQueueFrame src;
    int ret;

    av_assert0(st->samples_queued >= nb_samples);

    ret = av_fifo_peek(st->fifo, &src, 1, 0);
    av_assert0(ret >= 0);

    // peeked frame has enough samples and its data is aligned
    // -> we can just make a reference and limit its sample count
    if (src.f->nb_samples > nb_samples && frame_is_aligned(sq, src.f)) {
        ret = av_frame_ref(dst, src.f);
        if (ret < 0)
            return ret;

        dst->nb_samples = nb_samples;
        offset_audio(src.f, nb_samples);
        st->samples_queued -= nb_samples;

        goto finish;
    }

    // otherwise allocate a new frame and copy the data
    ret = av_channel_layout_copy(&dst->ch_layout, &src.f->ch_layout);
    if (ret < 0)
        return ret;

    dst->format     = src.f->format;
    dst->nb_samples = nb_samples;

    ret = av_frame_get_buffer(dst, 0);
    if (ret < 0)
        goto fail;

    ret = av_frame_copy_props(dst, src.f);
    if (ret < 0)
        goto fail;

    dst->nb_samples = 0;
    while (dst->nb_samples < nb_samples) {
        int to_copy;

        ret = av_fifo_peek(st->fifo, &src, 1, 0);
        av_assert0(ret >= 0);

        to_copy = FFMIN(nb_samples - dst->nb_samples, src.f->nb_samples);

        av_samples_copy(dst->extended_data, src.f->extended_data, dst->nb_samples,
                        0, to_copy, dst->ch_layout.nb_channels, dst->format);

        if (to_copy < src.f->nb_samples)
            offset_audio(src.f, to_copy);
        else {
            av_frame_unref(src.f);
            objpool_release(sq->pool, (void**)&src);
            av_fifo_drain2(st->fifo, 1);
        }
        st->samples_queued -= to_copy;

        dst->nb_samples += to_copy;
    }

finish:
    dst->duration   = av_rescale_q(nb_samples, (AVRational){ 1, dst->sample_rate },
                                   dst->time_base);

    return 0;

fail:
    av_frame_unref(dst);
    return ret;
}

static int receive_for_stream(SyncQueue *sq, unsigned int stream_idx,
                              SyncQueueFrame frame)
{
    SyncQueueStream *st_head = sq->head_stream >= 0 ?
                               &sq->streams[sq->head_stream] : NULL;
    SyncQueueStream *st;

    av_assert0(stream_idx < sq->nb_streams);
    st = &sq->streams[stream_idx];

    if (av_fifo_can_read(st->fifo) &&
        (st->frame_samples <= st->samples_queued || st->finished)) {
        int nb_samples = st->frame_samples;
        SyncQueueFrame peek;
        int64_t ts;
        int cmp = 1;

        if (st->finished)
            nb_samples = FFMIN(nb_samples, st->samples_queued);

        av_fifo_peek(st->fifo, &peek, 1, 0);
        ts = frame_end(sq, peek, nb_samples);

        /* check if this stream's tail timestamp does not overtake
         * the overall queue head */
        if (ts != AV_NOPTS_VALUE && st_head)
            cmp = av_compare_ts(ts, st->tb, st_head->head_ts, st_head->tb);

        /* We can release frames that do not end after the queue head.
         * Frames with no timestamps are just passed through with no conditions.
         * Frames are also passed through when there are no limiting streams.
         */
        if (cmp <= 0 || ts == AV_NOPTS_VALUE || !sq->have_limiting) {
            if (nb_samples &&
                (nb_samples != peek.f->nb_samples || !frame_is_aligned(sq, peek.f))) {
                int ret = receive_samples(sq, st, frame.f, nb_samples);
                if (ret < 0)
                    return ret;
            } else {
                frame_move(sq, frame, peek);
                objpool_release(sq->pool, (void**)&peek);
                av_fifo_drain2(st->fifo, 1);
                av_assert0(st->samples_queued >= frame_samples(sq, frame));
                st->samples_queued -= frame_samples(sq, frame);
            }

            av_log(sq->logctx, AV_LOG_DEBUG,
                   "sq: receive %u ts %s queue head %d ts %s\n", stream_idx,
                   av_ts2timestr(frame_end(sq, frame, 0), &st->tb),
                   sq->head_stream,
                   st_head ? av_ts2timestr(st_head->head_ts, &st_head->tb) : "N/A");

            return 0;
        }
    }

    return (sq->finished || (st->finished && !av_fifo_can_read(st->fifo))) ?
            AVERROR_EOF : AVERROR(EAGAIN);
}

static int receive_internal(SyncQueue *sq, int stream_idx, SyncQueueFrame frame)
{
    int nb_eof = 0;
    int ret;

    /* read a frame for a specific stream */
    if (stream_idx >= 0) {
        ret = receive_for_stream(sq, stream_idx, frame);
        return (ret < 0) ? ret : stream_idx;
    }

    /* read a frame for any stream with available output */
    for (unsigned int i = 0; i < sq->nb_streams; i++) {
        ret = receive_for_stream(sq, i, frame);
        if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) {
            nb_eof += (ret == AVERROR_EOF);
            continue;
        }
        return (ret < 0) ? ret : i;
    }

    return (nb_eof == sq->nb_streams) ? AVERROR_EOF : AVERROR(EAGAIN);
}

int sq_receive(SyncQueue *sq, int stream_idx, SyncQueueFrame frame)
{
    int ret = receive_internal(sq, stream_idx, frame);

    /* try again if the queue overflowed and triggered a fake heartbeat
     * for lagging streams */
    if (ret == AVERROR(EAGAIN) && overflow_heartbeat(sq, stream_idx))
        ret = receive_internal(sq, stream_idx, frame);

    return ret;
}

int sq_add_stream(SyncQueue *sq, int limiting)
{
    SyncQueueStream *tmp, *st;

    tmp = av_realloc_array(sq->streams, sq->nb_streams + 1, sizeof(*sq->streams));
    if (!tmp)
        return AVERROR(ENOMEM);
    sq->streams = tmp;

    st = &sq->streams[sq->nb_streams];
    memset(st, 0, sizeof(*st));

    st->fifo = av_fifo_alloc2(1, sizeof(SyncQueueFrame), AV_FIFO_FLAG_AUTO_GROW);
    if (!st->fifo)
        return AVERROR(ENOMEM);

    /* we set a valid default, so that a pathological stream that never
     * receives even a real timebase (and no frames) won't stall all other
     * streams forever; cf. overflow_heartbeat() */
    st->tb      = (AVRational){ 1, 1 };
    st->head_ts = AV_NOPTS_VALUE;
    st->frames_max = UINT64_MAX;
    st->limiting   = limiting;

    sq->have_limiting |= limiting;

    return sq->nb_streams++;
}

void sq_limit_frames(SyncQueue *sq, unsigned int stream_idx, uint64_t frames)
{
    SyncQueueStream *st;

    av_assert0(stream_idx < sq->nb_streams);
    st = &sq->streams[stream_idx];

    st->frames_max = frames;
    if (st->frames_sent >= st->frames_max)
        finish_stream(sq, stream_idx);
}

void sq_frame_samples(SyncQueue *sq, unsigned int stream_idx,
                      int frame_samples)
{
    SyncQueueStream *st;

    av_assert0(sq->type == SYNC_QUEUE_FRAMES);
    av_assert0(stream_idx < sq->nb_streams);
    st = &sq->streams[stream_idx];

    st->frame_samples = frame_samples;

    sq->align_mask = av_cpu_max_align() - 1;
}

SyncQueue *sq_alloc(enum SyncQueueType type, int64_t buf_size_us, void *logctx)
{
    SyncQueue *sq = av_mallocz(sizeof(*sq));

    if (!sq)
        return NULL;

    sq->type                 = type;
    sq->buf_size_us          = buf_size_us;
    sq->logctx               = logctx;

    sq->head_stream          = -1;
    sq->head_finished_stream = -1;

    sq->pool = (type == SYNC_QUEUE_PACKETS) ? objpool_alloc_packets() :
                                              objpool_alloc_frames();
    if (!sq->pool) {
        av_freep(&sq);
        return NULL;
    }

    return sq;
}

void sq_free(SyncQueue **psq)
{
    SyncQueue *sq = *psq;

    if (!sq)
        return;

    for (unsigned int i = 0; i < sq->nb_streams; i++) {
        SyncQueueFrame frame;
        while (av_fifo_read(sq->streams[i].fifo, &frame, 1) >= 0)
            objpool_release(sq->pool, (void**)&frame);

        av_fifo_freep2(&sq->streams[i].fifo);
    }

    av_freep(&sq->streams);

    objpool_free(&sq->pool);

    av_freep(psq);
}