movenc.c

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/*
 * Copyright (c) 2015 Martin Storsjo
 *
 * 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 "config.h"
 
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "libavutil/md5.h"
 
#include "libavformat/avformat.h"
 
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
 
#if !HAVE_GETOPT
#include "compat/getopt.c"
#endif
 
#define HASH_SIZE 16
 
static const uint8_t h264_extradata[] = {
    0x01, 0x4d, 0x40, 0x1e, 0xff, 0xe1, 0x00, 0x02, 0x67, 0x4d, 0x01, 0x00, 0x02, 0x68, 0xef
};
static const uint8_t aac_extradata[] = {
    0x12, 0x10
};
 
 
static const char *format = "mp4";
AVFormatContext *ctx;
uint8_t iobuf[32768];
AVDictionary *opts;
 
int write_file;
const char *cur_name;
FILE* out;
int out_size;
struct AVMD5* md5;
uint8_t hash[HASH_SIZE];
 
AVStream *video_st, *audio_st;
int64_t audio_dts, video_dts;
 
int bframes;
int64_t duration;
int64_t audio_duration;
int frames;
int gop_size;
int64_t next_p_pts;
enum AVPictureType last_picture;
int skip_write;
int skip_write_audio;
int clear_duration;
int force_iobuf_size;
int do_interleave;
int fake_pkt_duration;
 
int num_warnings;
 
int check_faults;
 
 
static void count_warnings(void *avcl, int level, const char *fmt, va_list vl)
{
    if (level == AV_LOG_WARNING)
        num_warnings++;
}
 
static void init_count_warnings(void)
{
    av_log_set_callback(count_warnings);
    num_warnings = 0;
}
 
static void reset_count_warnings(void)
{
    av_log_set_callback(av_log_default_callback);
}
 
static int io_write(void *opaque, uint8_t *buf, int size)
{
    out_size += size;
    av_md5_update(md5, buf, size);
    if (out)
        fwrite(buf, 1, size, out);
    return size;
}
 
static int io_write_data_type(void *opaque, uint8_t *buf, int size,
                              enum AVIODataMarkerType type, int64_t time)
{
    char timebuf[30], content[5] = { 0 };
    const char *str;
    switch (type) {
    case AVIO_DATA_MARKER_HEADER:         str = "header";   break;
    case AVIO_DATA_MARKER_SYNC_POINT:     str = "sync";     break;
    case AVIO_DATA_MARKER_BOUNDARY_POINT: str = "boundary"; break;
    case AVIO_DATA_MARKER_UNKNOWN:        str = "unknown";  break;
    case AVIO_DATA_MARKER_TRAILER:        str = "trailer";  break;
    default:                              str = "unknown";  break;
    }
    if (time == AV_NOPTS_VALUE)
        snprintf(timebuf, sizeof(timebuf), "nopts");
    else
        snprintf(timebuf, sizeof(timebuf), "%"PRId64, time);
    // There can be multiple header/trailer callbacks, only log the box type
    // for header at out_size == 0
    if (type != AVIO_DATA_MARKER_UNKNOWN &&
        type != AVIO_DATA_MARKER_TRAILER &&
        (type != AVIO_DATA_MARKER_HEADER || out_size == 0) &&
        size >= 8)
        memcpy(content, &buf[4], 4);
    else
        snprintf(content, sizeof(content), "-");
    printf("write_data len %d, time %s, type %s atom %s\n", size, timebuf, str, content);
    return io_write(opaque, buf, size);
}
 
static void init_out(const char *name)
{
    char buf[100];
    cur_name = name;
    snprintf(buf, sizeof(buf), "%s.%s", cur_name, format);
 
    av_md5_init(md5);
    if (write_file) {
        out = fopen(buf, "wb");
        if (!out)
            perror(buf);
    }
    out_size = 0;
}
 
static void close_out(void)
{
    int i;
    av_md5_final(md5, hash);
    for (i = 0; i < HASH_SIZE; i++)
        printf("%02x", hash[i]);
    printf(" %d %s\n", out_size, cur_name);
    if (out)
        fclose(out);
    out = NULL;
}
 
static void check_func(int value, int line, const char *msg, ...)
{
    if (!value) {
        va_list ap;
        va_start(ap, msg);
        printf("%d: ", line);
        vprintf(msg, ap);
        printf("\n");
        check_faults++;
        va_end(ap);
    }
}
#define check(value, ...) check_func(value, __LINE__, __VA_ARGS__)
 
static void init_fps(int bf, int audio_preroll, int fps)
{
    AVStream *st;
    int iobuf_size = force_iobuf_size ? force_iobuf_size : sizeof(iobuf);
    ctx = avformat_alloc_context();
    if (!ctx)
        exit(1);
    ctx->oformat = av_guess_format(format, NULL, NULL);
    if (!ctx->oformat)
        exit(1);
    ctx->pb = avio_alloc_context(iobuf, iobuf_size, AVIO_FLAG_WRITE, NULL, NULL, io_write, NULL);
    if (!ctx->pb)
        exit(1);
    ctx->pb->write_data_type = io_write_data_type;
    ctx->flags |= AVFMT_FLAG_BITEXACT;
 
    st = avformat_new_stream(ctx, NULL);
    if (!st)
        exit(1);
    st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
    st->codecpar->codec_id = AV_CODEC_ID_H264;
    st->codecpar->width = 640;
    st->codecpar->height = 480;
    st->time_base.num = 1;
    st->time_base.den = 30;
    st->codecpar->extradata_size = sizeof(h264_extradata);
    st->codecpar->extradata = av_mallocz(st->codecpar->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!st->codecpar->extradata)
        exit(1);
    memcpy(st->codecpar->extradata, h264_extradata, sizeof(h264_extradata));
    video_st = st;
 
    st = avformat_new_stream(ctx, NULL);
    if (!st)
        exit(1);
    st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
    st->codecpar->codec_id = AV_CODEC_ID_AAC;
    st->codecpar->sample_rate = 44100;
    st->codecpar->channels = 2;
    st->time_base.num = 1;
    st->time_base.den = 44100;
    st->codecpar->extradata_size = sizeof(aac_extradata);
    st->codecpar->extradata = av_mallocz(st->codecpar->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE);
    if (!st->codecpar->extradata)
        exit(1);
    memcpy(st->codecpar->extradata, aac_extradata, sizeof(aac_extradata));
    audio_st = st;
 
    if (avformat_write_header(ctx, &opts) < 0)
        exit(1);
    av_dict_free(&opts);
 
    frames = 0;
    gop_size = 30;
    duration = video_st->time_base.den / fps;
    audio_duration = 1024LL * audio_st->time_base.den / audio_st->codecpar->sample_rate;
    if (audio_preroll)
        audio_preroll = 2048LL * audio_st->time_base.den / audio_st->codecpar->sample_rate;
 
    bframes = bf;
    video_dts = bframes ? -duration : 0;
    audio_dts = -audio_preroll;
}
 
static void init(int bf, int audio_preroll)
{
    init_fps(bf, audio_preroll, 30);
}
 
static void mux_frames(int n, int c)
{
    int end_frames = frames + n;
    while (1) {
        AVPacket pkt;
        uint8_t pktdata[8] = { 0 };
        av_init_packet(&pkt);
 
        if (av_compare_ts(audio_dts, audio_st->time_base, video_dts, video_st->time_base) < 0) {
            pkt.dts = pkt.pts = audio_dts;
            pkt.stream_index = 1;
            pkt.duration = audio_duration;
            audio_dts += audio_duration;
        } else {
            if (frames == end_frames)
                break;
            pkt.dts = video_dts;
            pkt.stream_index = 0;
            pkt.duration = duration;
            if ((frames % gop_size) == 0) {
                pkt.flags |= AV_PKT_FLAG_KEY;
                last_picture = AV_PICTURE_TYPE_I;
                pkt.pts = pkt.dts + duration;
                video_dts = pkt.pts;
            } else {
                if (last_picture == AV_PICTURE_TYPE_P) {
                    last_picture = AV_PICTURE_TYPE_B;
                    pkt.pts = pkt.dts;
                    video_dts = next_p_pts;
                } else {
                    last_picture = AV_PICTURE_TYPE_P;
                    if (((frames + 1) % gop_size) == 0) {
                        pkt.pts = pkt.dts + duration;
                        video_dts = pkt.pts;
                    } else {
                        next_p_pts = pkt.pts = pkt.dts + 2 * duration;
                        video_dts += duration;
                    }
                }
            }
            if (!bframes)
                pkt.pts = pkt.dts;
            if (fake_pkt_duration)
                pkt.duration = fake_pkt_duration;
            frames++;
        }
 
        if (clear_duration)
            pkt.duration = 0;
        AV_WB32(pktdata + 4, pkt.pts);
        pkt.data = pktdata;
        pkt.size = 8;
        if (skip_write)
            continue;
        if (skip_write_audio && pkt.stream_index == 1)
            continue;
 
        if (c) {
            pkt.pts += (1LL<<32);
            pkt.dts += (1LL<<32);
        }
 
        if (do_interleave)
            av_interleaved_write_frame(ctx, &pkt);
        else
            av_write_frame(ctx, &pkt);
    }
}
 
static void mux_gops(int n)
{
    mux_frames(gop_size * n, 0);
}
 
static void skip_gops(int n)
{
    skip_write = 1;
    mux_gops(n);
    skip_write = 0;
}
 
static void signal_init_ts(void)
{
    AVPacket pkt;
    av_init_packet(&pkt);
    pkt.size = 0;
    pkt.data = NULL;
 
    pkt.stream_index = 0;
    pkt.dts = video_dts;
    pkt.pts = 0;
    av_write_frame(ctx, &pkt);
 
    pkt.stream_index = 1;
    pkt.dts = pkt.pts = audio_dts;
    av_write_frame(ctx, &pkt);
}
 
static void finish(void)
{
    av_write_trailer(ctx);
    avio_context_free(&ctx->pb);
    avformat_free_context(ctx);
    ctx = NULL;
}
 
static void help(void)
{
    printf("movenc-test [-w]\n"
           "-w          write output into files\n");
}
 
int main(int argc, char **argv)
{
    int c;
    uint8_t header[HASH_SIZE];
    uint8_t content[HASH_SIZE];
    int empty_moov_pos;
    int prev_pos;
 
    for (;;) {
        c = getopt(argc, argv, "wh");
        if (c == -1)
            break;
        switch (c) {
        case 'w':
            write_file = 1;
            break;
        default:
        case 'h':
            help();
            return 0;
        }
    }
 
    md5 = av_md5_alloc();
    if (!md5)
        return 1;
 
    // Write a fragmented file with an initial moov that actually contains some
    // samples. One moov+mdat with 1 second of data and one moof+mdat with 1
    // second of data.
    init_out("non-empty-moov");
    av_dict_set(&opts, "movflags", "frag_keyframe", 0);
    init(0, 0);
    mux_gops(2);
    finish();
    close_out();
 
    // Write a similar file, but with B-frames and audio preroll, handled
    // via an edit list.
    init_out("non-empty-moov-elst");
    av_dict_set(&opts, "movflags", "frag_keyframe", 0);
    av_dict_set(&opts, "use_editlist", "1", 0);
    init(1, 1);
    mux_gops(2);
    finish();
    close_out();
 
    // Use B-frames but no audio-preroll, but without an edit list.
    // Due to avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO, the dts
    // of the first audio packet is > 0, but it is set to zero since edit
    // lists aren't used, increasing the duration of the first packet instead.
    init_out("non-empty-moov-no-elst");
    av_dict_set(&opts, "movflags", "frag_keyframe", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(1, 0);
    mux_gops(2);
    finish();
    close_out();
 
    format = "ismv";
    // Write an ISMV, with B-frames and audio preroll.
    init_out("ismv");
    av_dict_set(&opts, "movflags", "frag_keyframe", 0);
    init(1, 1);
    mux_gops(2);
    finish();
    close_out();
    format = "mp4";
 
    // An initial moov that doesn't contain any samples, followed by two
    // moof+mdat pairs.
    init_out("empty-moov");
    av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(0, 0);
    mux_gops(2);
    finish();
    close_out();
    memcpy(content, hash, HASH_SIZE);
 
    // Similar to the previous one, but with input that doesn't start at
    // pts/dts 0. avoid_negative_ts behaves in the same way as
    // in non-empty-moov-no-elst above.
    init_out("empty-moov-no-elst");
    av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov", 0);
    init(1, 0);
    mux_gops(2);
    finish();
    close_out();
 
    // Same as the previous one, but disable avoid_negative_ts (which
    // would require using an edit list, but with empty_moov, one can't
    // write a sensible edit list, when the start timestamps aren't known).
    // This should trigger a warning - we check that the warning is produced.
    init_count_warnings();
    init_out("empty-moov-no-elst-no-adjust");
    av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov", 0);
    av_dict_set(&opts, "avoid_negative_ts", "0", 0);
    init(1, 0);
    mux_gops(2);
    finish();
    close_out();
 
    reset_count_warnings();
    check(num_warnings > 0, "No warnings printed for unhandled start offset");
 
    // Verify that delay_moov produces the same as empty_moov for
    // simple input
    init_out("delay-moov");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(0, 0);
    mux_gops(2);
    finish();
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "delay_moov differs from empty_moov");
 
    // Test writing content that requires an edit list using delay_moov
    init_out("delay-moov-elst");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov", 0);
    init(1, 1);
    mux_gops(2);
    finish();
    close_out();
 
    // Test writing a file with one track lacking packets, with delay_moov.
    skip_write_audio = 1;
    init_out("delay-moov-empty-track");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov", 0);
    init(0, 0);
    mux_gops(2);
    // The automatic flushing shouldn't output anything, since we're still
    // waiting for data for some tracks
    check(out_size == 0, "delay_moov flushed prematurely");
    // When closed (or manually flushed), all the written data should still
    // be output.
    finish();
    close_out();
    check(out_size > 0, "delay_moov didn't output anything");
 
    // Check that manually flushing still outputs things as expected. This
    // produces two fragments, while the one above produces only one.
    init_out("delay-moov-empty-track-flush");
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov", 0);
    init(0, 0);
    mux_gops(1);
    av_write_frame(ctx, NULL); // Force writing the moov
    check(out_size > 0, "No moov written");
    av_write_frame(ctx, NULL);
    mux_gops(1);
    av_write_frame(ctx, NULL);
    finish();
    close_out();
 
    skip_write_audio = 0;
 
 
 
    // Verify that the header written by delay_moov when manually flushed
    // is identical to the one by empty_moov.
    init_out("empty-moov-header");
    av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(0, 0);
    close_out();
    memcpy(header, hash, HASH_SIZE);
    init_out("empty-moov-content");
    mux_gops(2);
    // Written 2 seconds of content, with an automatic flush after 1 second.
    check(out_size > 0, "No automatic flush?");
    empty_moov_pos = prev_pos = out_size;
    // Manually flush the second fragment
    av_write_frame(ctx, NULL);
    check(out_size > prev_pos, "No second fragment flushed?");
    prev_pos = out_size;
    // Check that an extra flush doesn't output any more data
    av_write_frame(ctx, NULL);
    check(out_size == prev_pos, "More data written?");
    close_out();
    memcpy(content, hash, HASH_SIZE);
    // Ignore the trailer written here
    finish();
 
    init_out("delay-moov-header");
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(0, 0);
    check(out_size == 0, "Output written during init with delay_moov");
    mux_gops(1); // Write 1 second of content
    av_write_frame(ctx, NULL); // Force writing the moov
    close_out();
    check(!memcmp(hash, header, HASH_SIZE), "delay_moov header differs from empty_moov");
    init_out("delay-moov-content");
    av_write_frame(ctx, NULL); // Flush the first fragment
    check(out_size == empty_moov_pos, "Manually flushed content differs from automatically flushed, %d vs %d", out_size, empty_moov_pos);
    mux_gops(1); // Write the rest of the content
    av_write_frame(ctx, NULL); // Flush the second fragment
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "delay_moov content differs from empty_moov");
    finish();
 
 
    // Verify that we can produce an identical second fragment without
    // writing the first one. First write the reference fragments that
    // we want to reproduce.
    av_dict_set(&opts, "movflags", "frag_custom+empty_moov+dash", 0);
    init(0, 0);
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the first fragment
    init_out("empty-moov-second-frag");
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    memcpy(content, hash, HASH_SIZE);
    finish();
 
    // Produce the same second fragment without actually writing the first
    // one before.
    av_dict_set(&opts, "movflags", "frag_custom+empty_moov+dash+frag_discont", 0);
    av_dict_set(&opts, "fragment_index", "2", 0);
    av_dict_set(&opts, "avoid_negative_ts", "0", 0);
    av_dict_set(&opts, "use_editlist", "0", 0);
    init(0, 0);
    skip_gops(1);
    init_out("empty-moov-second-frag-discont");
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "discontinuously written fragment differs");
    finish();
 
    // Produce the same thing by using delay_moov, which requires a slightly
    // different call sequence.
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash+frag_discont", 0);
    av_dict_set(&opts, "fragment_index", "2", 0);
    init(0, 0);
    skip_gops(1);
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the moov
    init_out("delay-moov-second-frag-discont");
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "discontinuously written fragment differs");
    finish();
 
 
    // Test discontinuously written fragments with B-frames (where the
    // assumption of starting at pts=0 works) but not with audio preroll
    // (which can't be guessed).
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash", 0);
    init(1, 0);
    mux_gops(1);
    init_out("delay-moov-elst-init");
    av_write_frame(ctx, NULL); // Output the moov
    close_out();
    memcpy(header, hash, HASH_SIZE);
    av_write_frame(ctx, NULL); // Output the first fragment
    init_out("delay-moov-elst-second-frag");
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    memcpy(content, hash, HASH_SIZE);
    finish();
 
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash+frag_discont", 0);
    av_dict_set(&opts, "fragment_index", "2", 0);
    init(1, 0);
    skip_gops(1);
    mux_gops(1); // Write the second fragment
    init_out("delay-moov-elst-init-discont");
    av_write_frame(ctx, NULL); // Output the moov
    close_out();
    check(!memcmp(hash, header, HASH_SIZE), "discontinuously written header differs");
    init_out("delay-moov-elst-second-frag-discont");
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "discontinuously written fragment differs");
    finish();
 
 
    // Test discontinuously written fragments with B-frames and audio preroll,
    // properly signaled.
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash", 0);
    init(1, 1);
    mux_gops(1);
    init_out("delay-moov-elst-signal-init");
    av_write_frame(ctx, NULL); // Output the moov
    close_out();
    memcpy(header, hash, HASH_SIZE);
    av_write_frame(ctx, NULL); // Output the first fragment
    init_out("delay-moov-elst-signal-second-frag");
    mux_gops(1);
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    memcpy(content, hash, HASH_SIZE);
    finish();
 
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash+frag_discont", 0);
    av_dict_set(&opts, "fragment_index", "2", 0);
    init(1, 1);
    signal_init_ts();
    skip_gops(1);
    mux_gops(1); // Write the second fragment
    init_out("delay-moov-elst-signal-init-discont");
    av_write_frame(ctx, NULL); // Output the moov
    close_out();
    check(!memcmp(hash, header, HASH_SIZE), "discontinuously written header differs");
    init_out("delay-moov-elst-signal-second-frag-discont");
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    check(!memcmp(hash, content, HASH_SIZE), "discontinuously written fragment differs");
    finish();
 
 
    // Test muxing discontinuous fragments with very large (> (1<<31)) timestamps.
    av_dict_set(&opts, "movflags", "frag_custom+delay_moov+dash+frag_discont", 0);
    av_dict_set(&opts, "fragment_index", "2", 0);
    init(1, 1);
    signal_init_ts();
    skip_gops(1);
    mux_frames(gop_size, 1); // Write the second fragment
    init_out("delay-moov-elst-signal-init-discont-largets");
    av_write_frame(ctx, NULL); // Output the moov
    close_out();
    init_out("delay-moov-elst-signal-second-frag-discont-largets");
    av_write_frame(ctx, NULL); // Output the second fragment
    close_out();
    finish();
 
    // Test VFR content, with sidx atoms (which declare the pts duration
    // of a fragment, forcing overriding the start pts of the next one).
    // Here, the fragment duration in pts is significantly different from
    // the duration in dts. The video stream starts at dts=-10,pts=0, and
    // the second fragment starts at dts=155,pts=156. The trun duration sum
    // of the first fragment is 165, which also is written as
    // baseMediaDecodeTime in the tfdt in the second fragment. The sidx for
    // the first fragment says earliest_presentation_time = 0 and
    // subsegment_duration = 156, which also matches the sidx in the second
    // fragment. For the audio stream, the pts and dts durations also don't
    // match - the input stream starts at pts=-2048, but that part is excluded
    // by the edit list.
    init_out("vfr");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov+dash", 0);
    init_fps(1, 1, 3);
    mux_frames(gop_size/2, 0);
    duration /= 10;
    mux_frames(gop_size/2, 0);
    mux_gops(1);
    finish();
    close_out();
 
    // Test VFR content, with cleared duration fields. In these cases,
    // the muxer must guess the duration of the last packet of each
    // fragment. As long as the framerate doesn't vary (too much) at the
    // fragment edge, it works just fine. Additionally, when automatically
    // cutting fragments, the muxer already know the timestamps of the next
    // packet for one stream (in most cases the video stream), avoiding
    // having to use guesses for that one.
    init_count_warnings();
    clear_duration = 1;
    init_out("vfr-noduration");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov+dash", 0);
    init_fps(1, 1, 3);
    mux_frames(gop_size/2, 0);
    duration /= 10;
    mux_frames(gop_size/2, 0);
    mux_gops(1);
    finish();
    close_out();
    clear_duration = 0;
    reset_count_warnings();
    check(num_warnings > 0, "No warnings printed for filled in durations");
 
    // Test with an IO buffer size that is too small to hold a full fragment;
    // this will cause write_data_type to be called with the type unknown.
    force_iobuf_size = 1500;
    init_out("large_frag");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov", 0);
    init_fps(1, 1, 3);
    mux_gops(2);
    finish();
    close_out();
    force_iobuf_size = 0;
 
    // Test VFR content with bframes with interleaving.
    // Here, using av_interleaved_write_frame allows the muxer to get the
    // fragment end durations right. We always set the packet duration to
    // the expected, but we simulate dropped frames at one point.
    do_interleave = 1;
    init_out("vfr-noduration-interleave");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov", 0);
    av_dict_set(&opts, "frag_duration", "650000", 0);
    init_fps(1, 1, 30);
    mux_frames(gop_size/2, 0);
    // Pretend that the packet duration is the normal, even if
    // we actually skip a bunch of frames. (I.e., simulate that
    // we don't know of the framedrop in advance.)
    fake_pkt_duration = duration;
    duration *= 10;
    mux_frames(1, 0);
    fake_pkt_duration = 0;
    duration /= 10;
    mux_frames(gop_size/2 - 1, 0);
    mux_gops(1);
    finish();
    close_out();
    clear_duration = 0;
    do_interleave = 0;
 
    // Write a fragmented file with b-frames and audio preroll,
    // with negative cts values, removing the edit list for the
    // video track.
    init_out("delay-moov-elst-neg-cts");
    av_dict_set(&opts, "movflags", "frag_keyframe+delay_moov+negative_cts_offsets", 0);
    init(1, 1);
    mux_gops(2);
    finish();
    close_out();
 
    // Write a fragmented file with b-frames without audio preroll,
    // with negative cts values, avoiding any edit lists, allowing
    // to use empty_moov instead of delay_moov.
    init_out("empty-moov-neg-cts");
    av_dict_set(&opts, "movflags", "frag_keyframe+empty_moov+negative_cts_offsets", 0);
    init(1, 0);
    mux_gops(2);
    finish();
    close_out();
 
    av_free(md5);
 
    return check_faults > 0 ? 1 : 0;
}