static int process_input(int file_index)

{

    InputFile *ifile = input_files[file_index];

    AVFormatContext *is;

    InputStream *ist;

    AVPacket pkt;

    int ret, i, j;

    int64_t duration;

    int64_t pkt_dts;



    is  = ifile->ctx;

    ret = get_input_packet(ifile, &pkt);



    if (ret == AVERROR(EAGAIN)) {

        ifile->eagain = 1;

        return ret;

    }

    if (ret < 0 && ifile->loop) {

        if ((ret = seek_to_start(ifile, is)) < 0)

            return ret;

        ret = get_input_packet(ifile, &pkt);

    }

    if (ret < 0) {

        if (ret != AVERROR_EOF) {

            print_error(is->filename, ret);

            if (exit_on_error)

                exit_program(1);

        }



        for (i = 0; i < ifile->nb_streams; i++) {

            ist = input_streams[ifile->ist_index + i];

            if (ist->decoding_needed) {

                ret = process_input_packet(ist, NULL, 0);

                if (ret>0)

                    return 0;

            }



            /* mark all outputs that don't go through lavfi as finished */

            for (j = 0; j < nb_output_streams; j++) {

                OutputStream *ost = output_streams[j];



                if (ost->source_index == ifile->ist_index + i &&

                    (ost->stream_copy || ost->enc->type == AVMEDIA_TYPE_SUBTITLE))

                    finish_output_stream(ost);

            }

        }



        ifile->eof_reached = 1;

        return AVERROR(EAGAIN);

    }



    reset_eagain();



    if (do_pkt_dump) {

        av_pkt_dump_log2(NULL, AV_LOG_DEBUG, &pkt, do_hex_dump,

                         is->streams[pkt.stream_index]);

    }

    /* the following test is needed in case new streams appear

       dynamically in stream : we ignore them */

    if (pkt.stream_index >= ifile->nb_streams) {

        report_new_stream(file_index, &pkt);

        goto discard_packet;

    }



    ist = input_streams[ifile->ist_index + pkt.stream_index];



    ist->data_size += pkt.size;

    ist->nb_packets++;



    if (ist->discard)

        goto discard_packet;



    if (exit_on_error && (pkt.flags & AV_PKT_FLAG_CORRUPT)) {

        av_log(NULL, AV_LOG_FATAL, "%s: corrupt input packet in stream %d\n", is->filename, pkt.stream_index);

        exit_program(1);

    }



    if (debug_ts) {

        av_log(NULL, AV_LOG_INFO, "demuxer -> ist_index:%d type:%s "

               "next_dts:%s next_dts_time:%s next_pts:%s next_pts_time:%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->dec_ctx->codec_type),

               av_ts2str(ist->next_dts), av_ts2timestr(ist->next_dts, &AV_TIME_BASE_Q),

               av_ts2str(ist->next_pts), av_ts2timestr(ist->next_pts, &AV_TIME_BASE_Q),

               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));

    }



    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;

        }

    }



    /* add the stream-global side data to the first packet */

    if (ist->nb_packets == 1) {

        if (ist->st->nb_side_data)

            av_packet_split_side_data(&pkt);

        for (i = 0; i < ist->st->nb_side_data; i++) {

            AVPacketSideData *src_sd = &ist->st->side_data[i];

            uint8_t *dst_data;



            if (av_packet_get_side_data(&pkt, src_sd->type, NULL))

                continue;

            if (ist->autorotate && src_sd->type == AV_PKT_DATA_DISPLAYMATRIX)

                continue;



            dst_data = av_packet_new_side_data(&pkt, src_sd->type, src_sd->size);

            if (!dst_data)

                exit_program(1);



            memcpy(dst_data, src_sd->data, src_sd->size);

        }

    }



    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;



    pkt_dts = av_rescale_q_rnd(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);

    if ((ist->dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO ||

         ist->dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) &&

        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 delta   = pkt_dts - ifile->last_ts;

        if (delta < -1LL*dts_delta_threshold*AV_TIME_BASE ||

            delta >  1LL*dts_delta_threshold*AV_TIME_BASE){

            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);

        }

    }



    duration = av_rescale_q(ifile->duration, ifile->time_base, ist->st->time_base);

    if (pkt.pts != AV_NOPTS_VALUE) {

        pkt.pts += duration;

        ist->max_pts = FFMAX(pkt.pts, ist->max_pts);

        ist->min_pts = FFMIN(pkt.pts, ist->min_pts);

    }



    if (pkt.dts != AV_NOPTS_VALUE)

        pkt.dts += duration;



    pkt_dts = av_rescale_q_rnd(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q, AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX);

    if ((ist->dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO ||

         ist->dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) &&

         pkt_dts != AV_NOPTS_VALUE && ist->next_dts != AV_NOPTS_VALUE &&

        !copy_ts) {

        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 ||

                pkt_dts + AV_TIME_BASE/10 < FFMAX(ist->pts, ist->dts)) {

                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) {

                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) {

                    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->dec_ctx->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);



    process_input_packet(ist, &pkt, 0);



discard_packet:

    av_packet_unref(&pkt);



    return 0;

}
