ffmpeg.c

    if(!ist->wrap_correction_done && is->start_time != AV_NOPTS_VALUE && ist->st->pts_wrap_bits < 64){
        int64_t stime, stime2;
        // Correcting starttime based on the enabled streams
        // FIXME this ideally should be done before the first use of starttime but we do not know which are the enabled streams at that point.
        //       so we instead do it here as part of discontinuity handling
        if (   ist->next_dts == AV_NOPTS_VALUE
            && ifile->ts_offset == -is->start_time
            && (is->iformat->flags & AVFMT_TS_DISCONT)) {
            int64_t new_start_time = INT64_MAX;
            for (i=0; i<is->nb_streams; i++) {
                AVStream *st = is->streams[i];
                if(st->discard == AVDISCARD_ALL || st->start_time == AV_NOPTS_VALUE)
                    continue;
                new_start_time = FFMIN(new_start_time, av_rescale_q(st->start_time, st->time_base, AV_TIME_BASE_Q));
            }
            if (new_start_time > is->start_time) {
                av_log(is, AV_LOG_VERBOSE, "Correcting start time by %"PRId64"\n", new_start_time - is->start_time);
                ifile->ts_offset = -new_start_time;
            }
        }

        stime = av_rescale_q(is->start_time, AV_TIME_BASE_Q, ist->st->time_base);
        stime2= stime + (1ULL<<ist->st->pts_wrap_bits);
        ist->wrap_correction_done = 1;

        if(stime2 > stime && pkt.dts != AV_NOPTS_VALUE && pkt.dts > stime + (1LL<<(ist->st->pts_wrap_bits-1))) {
            pkt.dts -= 1ULL<<ist->st->pts_wrap_bits;
            ist->wrap_correction_done = 0;
        }
        if(stime2 > stime && pkt.pts != AV_NOPTS_VALUE && pkt.pts > stime + (1LL<<(ist->st->pts_wrap_bits-1))) {
            pkt.pts -= 1ULL<<ist->st->pts_wrap_bits;
            ist->wrap_correction_done = 0;
        }
    }

    if (pkt.dts != AV_NOPTS_VALUE)
        pkt.dts += av_rescale_q(ifile->ts_offset, AV_TIME_BASE_Q, ist->st->time_base);
    if (pkt.pts != AV_NOPTS_VALUE)
        pkt.pts += av_rescale_q(ifile->ts_offset, AV_TIME_BASE_Q, ist->st->time_base);

    if (pkt.pts != AV_NOPTS_VALUE)
        pkt.pts *= ist->ts_scale;
    if (pkt.dts != AV_NOPTS_VALUE)
        pkt.dts *= ist->ts_scale;

    if (pkt.dts != AV_NOPTS_VALUE && ist->next_dts == AV_NOPTS_VALUE && !copy_ts
        && (is->iformat->flags & AVFMT_TS_DISCONT) && ifile->last_ts != AV_NOPTS_VALUE) {
        int64_t pkt_dts = av_rescale_q(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q);
        int64_t delta   = pkt_dts - ifile->last_ts;
        if(delta < -1LL*dts_delta_threshold*AV_TIME_BASE ||
            (delta > 1LL*dts_delta_threshold*AV_TIME_BASE &&
                ist->st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE)){
            ifile->ts_offset -= delta;
            av_log(NULL, AV_LOG_DEBUG,
                   "Inter stream timestamp discontinuity %"PRId64", new offset= %"PRId64"\n",
                   delta, ifile->ts_offset);
            pkt.dts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
            if (pkt.pts != AV_NOPTS_VALUE)
                pkt.pts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
        }
    }

    if (pkt.dts != AV_NOPTS_VALUE && ist->next_dts != AV_NOPTS_VALUE &&
        !copy_ts) {
        int64_t pkt_dts = av_rescale_q(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q);
        int64_t delta   = pkt_dts - ist->next_dts;
        if (is->iformat->flags & AVFMT_TS_DISCONT) {
        if(delta < -1LL*dts_delta_threshold*AV_TIME_BASE ||
            (delta > 1LL*dts_delta_threshold*AV_TIME_BASE &&
                ist->st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE) ||
            pkt_dts + AV_TIME_BASE/10 < ist->pts){
            ifile->ts_offset -= delta;
            av_log(NULL, AV_LOG_DEBUG,
                   "timestamp discontinuity %"PRId64", new offset= %"PRId64"\n",
                   delta, ifile->ts_offset);
            pkt.dts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
            if (pkt.pts != AV_NOPTS_VALUE)
                pkt.pts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
        }
        } else {
            if ( delta < -1LL*dts_error_threshold*AV_TIME_BASE ||
                (delta > 1LL*dts_error_threshold*AV_TIME_BASE && ist->st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE)
               ) {
                av_log(NULL, AV_LOG_WARNING, "DTS %"PRId64", next:%"PRId64" st:%d invalid dropping\n", pkt.dts, ist->next_dts, pkt.stream_index);
                pkt.dts = AV_NOPTS_VALUE;
            }
            if (pkt.pts != AV_NOPTS_VALUE){
                int64_t pkt_pts = av_rescale_q(pkt.pts, ist->st->time_base, AV_TIME_BASE_Q);
                delta   = pkt_pts - ist->next_dts;
                if ( delta < -1LL*dts_error_threshold*AV_TIME_BASE ||
                    (delta > 1LL*dts_error_threshold*AV_TIME_BASE && ist->st->codec->codec_type != AVMEDIA_TYPE_SUBTITLE)
                   ) {
                    av_log(NULL, AV_LOG_WARNING, "PTS %"PRId64", next:%"PRId64" invalid dropping st:%d\n", pkt.pts, ist->next_dts, pkt.stream_index);
                    pkt.pts = AV_NOPTS_VALUE;
                }
            }
        }
    }

    if (pkt.dts != AV_NOPTS_VALUE)
        ifile->last_ts = av_rescale_q(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q);

    if (debug_ts) {
        av_log(NULL, AV_LOG_INFO, "demuxer+ffmpeg -> ist_index:%d type:%s pkt_pts:%s pkt_pts_time:%s pkt_dts:%s pkt_dts_time:%s off:%s off_time:%s\n",
               ifile->ist_index + pkt.stream_index, av_get_media_type_string(ist->st->codec->codec_type),
               av_ts2str(pkt.pts), av_ts2timestr(pkt.pts, &ist->st->time_base),
               av_ts2str(pkt.dts), av_ts2timestr(pkt.dts, &ist->st->time_base),
               av_ts2str(input_files[ist->file_index]->ts_offset),
               av_ts2timestr(input_files[ist->file_index]->ts_offset, &AV_TIME_BASE_Q));
    }

    sub2video_heartbeat(ist, pkt.pts);

    ret = output_packet(ist, &pkt);
    if (ret < 0) {
        char buf[128];
        av_strerror(ret, buf, sizeof(buf));
        av_log(NULL, AV_LOG_ERROR, "Error while decoding stream #%d:%d: %s\n",
                ist->file_index, ist->st->index, buf);
        if (exit_on_error)
            exit_program(1);
    }

discard_packet:
    av_free_packet(&pkt);

    return 0;
}

/**
 * Perform a step of transcoding for the specified filter graph.
 *
 * @param[in]  graph     filter graph to consider
 * @param[out] best_ist  input stream where a frame would allow to continue
 * @return  0 for success, <0 for error
 */
static int transcode_from_filter(FilterGraph *graph, InputStream **best_ist)
{
    int i, ret;
    int nb_requests, nb_requests_max = 0;
    InputFilter *ifilter;
    InputStream *ist;

    *best_ist = NULL;
    ret = avfilter_graph_request_oldest(graph->graph);
    if (ret >= 0)
        return reap_filters();

    if (ret == AVERROR_EOF) {
        ret = reap_filters();
        for (i = 0; i < graph->nb_outputs; i++)
            close_output_stream(graph->outputs[i]->ost);
        return ret;
    }
    if (ret != AVERROR(EAGAIN))
        return ret;

    for (i = 0; i < graph->nb_inputs; i++) {
        ifilter = graph->inputs[i];
        ist = ifilter->ist;
        if (input_files[ist->file_index]->eagain ||
            input_files[ist->file_index]->eof_reached)
            continue;
        nb_requests = av_buffersrc_get_nb_failed_requests(ifilter->filter);
        if (nb_requests > nb_requests_max) {
            nb_requests_max = nb_requests;
            *best_ist = ist;
        }
    }

    if (!*best_ist)
        for (i = 0; i < graph->nb_outputs; i++)
            graph->outputs[i]->ost->unavailable = 1;

    return 0;
}

/**
 * Run a single step of transcoding.
 *
 * @return  0 for success, <0 for error
 */
static int transcode_step(void)
{
    OutputStream *ost;
    InputStream  *ist;
    int ret;

    ost = choose_output();
    if (!ost) {
        if (got_eagain()) {
            reset_eagain();
            av_usleep(10000);
            return 0;
        }
        av_log(NULL, AV_LOG_VERBOSE, "No more inputs to read from, finishing.\n");
        return AVERROR_EOF;
    }

    if (ost->filter) {
        if ((ret = transcode_from_filter(ost->filter->graph, &ist)) < 0)
            return ret;
        if (!ist)
            return 0;
    } else {
        av_assert0(ost->source_index >= 0);
        ist = input_streams[ost->source_index];
    }

    ret = process_input(ist->file_index);
    if (ret == AVERROR(EAGAIN)) {
        if (input_files[ist->file_index]->eagain)
            ost->unavailable = 1;
        return 0;
    }
    if (ret < 0)
        return ret == AVERROR_EOF ? 0 : ret;

    return reap_filters();
}

/*
 * The following code is the main loop of the file converter
 */
static int transcode(void)
{
    int ret, i;
    AVFormatContext *os;
    OutputStream *ost;
    InputStream *ist;
    int64_t timer_start;

    ret = transcode_init();
    if (ret < 0)
        goto fail;

    if (stdin_interaction) {
        av_log(NULL, AV_LOG_INFO, "Press [q] to stop, [?] for help\n");
    }

    timer_start = av_gettime();

#if HAVE_PTHREADS
    if ((ret = init_input_threads()) < 0)
        goto fail;
#endif

    while (!received_sigterm) {
        int64_t cur_time= av_gettime();

        /* if 'q' pressed, exits */
        if (stdin_interaction)
            if (check_keyboard_interaction(cur_time) < 0)
                break;

        /* check if there's any stream where output is still needed */
        if (!need_output()) {
            av_log(NULL, AV_LOG_VERBOSE, "No more output streams to write to, finishing.\n");
            break;
        }

        ret = transcode_step();
        if (ret < 0) {
            if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN))
                continue;

            av_log(NULL, AV_LOG_ERROR, "Error while filtering.\n");
            break;
        }

        /* dump report by using the output first video and audio streams */
        print_report(0, timer_start, cur_time);
    }
#if HAVE_PTHREADS
    free_input_threads();
#endif

    /* at the end of stream, we must flush the decoder buffers */
    for (i = 0; i < nb_input_streams; i++) {
        ist = input_streams[i];
        if (!input_files[ist->file_index]->eof_reached && ist->decoding_needed) {
            output_packet(ist, NULL);
        }
    }
    flush_encoders();

    term_exit();

    /* write the trailer if needed and close file */
    for (i = 0; i < nb_output_files; i++) {
        os = output_files[i]->ctx;
        av_write_trailer(os);
    }

    /* dump report by using the first video and audio streams */
    print_report(1, timer_start, av_gettime());

    /* close each encoder */
    for (i = 0; i < nb_output_streams; i++) {
        ost = output_streams[i];
        if (ost->encoding_needed) {
            av_freep(&ost->st->codec->stats_in);
            avcodec_close(ost->st->codec);
        }
    }

    /* close each decoder */
    for (i = 0; i < nb_input_streams; i++) {
        ist = input_streams[i];
        if (ist->decoding_needed) {
            avcodec_close(ist->st->codec);
        }
    }

    /* finished ! */
    ret = 0;

 fail:
#if HAVE_PTHREADS
    free_input_threads();
#endif

    if (output_streams) {
        for (i = 0; i < nb_output_streams; i++) {
            ost = output_streams[i];
            if (ost) {
                if (ost->stream_copy)
                    av_freep(&ost->st->codec->extradata);
                if (ost->logfile) {
                    fclose(ost->logfile);
                    ost->logfile = NULL;
                }
                av_freep(&ost->st->codec->subtitle_header);
                av_freep(&ost->forced_kf_pts);
                av_freep(&ost->apad);
                av_dict_free(&ost->opts);
                av_dict_free(&ost->swr_opts);
                av_dict_free(&ost->resample_opts);
            }
        }
    }
    return ret;
}


static int64_t getutime(void)
{
#if HAVE_GETRUSAGE
    struct rusage rusage;

    getrusage(RUSAGE_SELF, &rusage);
    return (rusage.ru_utime.tv_sec * 1000000LL) + rusage.ru_utime.tv_usec;
#elif HAVE_GETPROCESSTIMES
    HANDLE proc;
    FILETIME c, e, k, u;
    proc = GetCurrentProcess();
    GetProcessTimes(proc, &c, &e, &k, &u);
    return ((int64_t) u.dwHighDateTime << 32 | u.dwLowDateTime) / 10;
#else
    return av_gettime();
#endif
}

static int64_t getmaxrss(void)
{
#if HAVE_GETRUSAGE && HAVE_STRUCT_RUSAGE_RU_MAXRSS
    struct rusage rusage;
    getrusage(RUSAGE_SELF, &rusage);
    return (int64_t)rusage.ru_maxrss * 1024;
#elif HAVE_GETPROCESSMEMORYINFO
    HANDLE proc;
    PROCESS_MEMORY_COUNTERS memcounters;
    proc = GetCurrentProcess();
    memcounters.cb = sizeof(memcounters);
    GetProcessMemoryInfo(proc, &memcounters, sizeof(memcounters));
    return memcounters.PeakPagefileUsage;
#else
    return 0;
#endif
}

static void log_callback_null(void *ptr, int level, const char *fmt, va_list vl)
{
}

int main(int argc, char **argv)
{
    int ret;
    int64_t ti;

    register_exit(ffmpeg_cleanup);

    setvbuf(stderr,NULL,_IONBF,0); /* win32 runtime needs this */

    av_log_set_flags(AV_LOG_SKIP_REPEATED);
    parse_loglevel(argc, argv, options);

    if(argc>1 && !strcmp(argv[1], "-d")){
        run_as_daemon=1;
        av_log_set_callback(log_callback_null);
        argc--;
        argv++;
    }

    avcodec_register_all();
#if CONFIG_AVDEVICE
    avdevice_register_all();
#endif
    avfilter_register_all();
    av_register_all();
    avformat_network_init();

    show_banner(argc, argv, options);

    term_init();

    /* parse options and open all input/output files */
    ret = ffmpeg_parse_options(argc, argv);
    if (ret < 0)
        exit_program(1);

    if (nb_output_files <= 0 && nb_input_files == 0) {
        show_usage();
        av_log(NULL, AV_LOG_WARNING, "Use -h to get full help or, even better, run 'man %s'\n", program_name);
        exit_program(1);
    }

    /* file converter / grab */
    if (nb_output_files <= 0) {
        av_log(NULL, AV_LOG_FATAL, "At least one output file must be specified\n");
        exit_program(1);
    }

//     if (nb_input_files == 0) {
//         av_log(NULL, AV_LOG_FATAL, "At least one input file must be specified\n");
//         exit_program(1);
//     }

    current_time = ti = getutime();
    if (transcode() < 0)
        exit_program(1);
    ti = getutime() - ti;
    if (do_benchmark) {
        printf("bench: utime=%0.3fs\n", ti / 1000000.0);
    }
    av_log(NULL, AV_LOG_DEBUG, "%"PRIu64" frames successfully decoded, %"PRIu64" decoding errors\n",
           decode_error_stat[0], decode_error_stat[1]);
    if ((decode_error_stat[0] + decode_error_stat[1]) * max_error_rate < decode_error_stat[1])
        exit_program(69);

    exit_program(received_nb_signals ? 255 : 0);
    return 0;
}