avconv.c

    if (pkt->pts != AV_NOPTS_VALUE)
        opkt.pts = av_rescale_q(pkt->pts, ist->st->time_base, ost->st->time_base) - ost_tb_start_time;
    else
        opkt.pts = AV_NOPTS_VALUE;

    if (pkt->dts == AV_NOPTS_VALUE)
        opkt.dts = av_rescale_q(ist->last_dts, AV_TIME_BASE_Q, ost->st->time_base);
    else
        opkt.dts = av_rescale_q(pkt->dts, ist->st->time_base, ost->st->time_base);
    opkt.dts -= ost_tb_start_time;

    opkt.duration = av_rescale_q(pkt->duration, ist->st->time_base, ost->st->time_base);
    opkt.flags    = pkt->flags;

    // FIXME remove the following 2 lines they shall be replaced by the bitstream filters
    if (  ost->st->codec->codec_id != AV_CODEC_ID_H264
       && ost->st->codec->codec_id != AV_CODEC_ID_MPEG1VIDEO
       && ost->st->codec->codec_id != AV_CODEC_ID_MPEG2VIDEO
       && ost->st->codec->codec_id != AV_CODEC_ID_VC1
       ) {
        if (av_parser_change(ist->st->parser, ost->st->codec, &opkt.data, &opkt.size, pkt->data, pkt->size, pkt->flags & AV_PKT_FLAG_KEY))
            opkt.destruct = av_destruct_packet;
    } else {
        opkt.data = pkt->data;
        opkt.size = pkt->size;
    }

    write_frame(of->ctx, &opkt, ost);
    ost->st->codec->frame_number++;
    av_free_packet(&opkt);
}

static void rate_emu_sleep(InputStream *ist)
{
    if (input_files[ist->file_index]->rate_emu) {
        int64_t pts = av_rescale(ist->last_dts, 1000000, AV_TIME_BASE);
        int64_t now = av_gettime() - ist->start;
        if (pts > now)
            av_usleep(pts - now);
    }
}

int guess_input_channel_layout(InputStream *ist)
{
    AVCodecContext *dec = ist->st->codec;

    if (!dec->channel_layout) {
        char layout_name[256];

        dec->channel_layout = av_get_default_channel_layout(dec->channels);
        if (!dec->channel_layout)
            return 0;
        av_get_channel_layout_string(layout_name, sizeof(layout_name),
                                     dec->channels, dec->channel_layout);
        av_log(NULL, AV_LOG_WARNING, "Guessed Channel Layout for  Input Stream "
               "#%d.%d : %s\n", ist->file_index, ist->st->index, layout_name);
    }
    return 1;
}

static int decode_audio(InputStream *ist, AVPacket *pkt, int *got_output)
{
    AVFrame *decoded_frame;
    AVCodecContext *avctx = ist->st->codec;
    int bps = av_get_bytes_per_sample(ist->st->codec->sample_fmt);
    int i, ret, resample_changed;

    if (!ist->decoded_frame && !(ist->decoded_frame = avcodec_alloc_frame()))
        return AVERROR(ENOMEM);
    else
        avcodec_get_frame_defaults(ist->decoded_frame);
    decoded_frame = ist->decoded_frame;

    ret = avcodec_decode_audio4(avctx, decoded_frame, got_output, pkt);
    if (!*got_output || ret < 0) {
        if (!pkt->size) {
            for (i = 0; i < ist->nb_filters; i++)
                av_buffersrc_buffer(ist->filters[i]->filter, NULL);
        }
        return ret;
    }

    /* if the decoder provides a pts, use it instead of the last packet pts.
       the decoder could be delaying output by a packet or more. */
    if (decoded_frame->pts != AV_NOPTS_VALUE)
        ist->next_dts = decoded_frame->pts;
    else if (pkt->pts != AV_NOPTS_VALUE) {
        decoded_frame->pts = pkt->pts;
        pkt->pts           = AV_NOPTS_VALUE;
    }

    // preprocess audio (volume)
    if (audio_volume != 256) {
        int decoded_data_size = decoded_frame->nb_samples * avctx->channels * bps;
        void *samples = decoded_frame->data[0];
        switch (avctx->sample_fmt) {
        case AV_SAMPLE_FMT_U8:
        {
            uint8_t *volp = samples;
            for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
                int v = (((*volp - 128) * audio_volume + 128) >> 8) + 128;
                *volp++ = av_clip_uint8(v);
            }
            break;
        }
        case AV_SAMPLE_FMT_S16:
        {
            int16_t *volp = samples;
            for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
                int v = ((*volp) * audio_volume + 128) >> 8;
                *volp++ = av_clip_int16(v);
            }
            break;
        }
        case AV_SAMPLE_FMT_S32:
        {
            int32_t *volp = samples;
            for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
                int64_t v = (((int64_t)*volp * audio_volume + 128) >> 8);
                *volp++ = av_clipl_int32(v);
            }
            break;
        }
        case AV_SAMPLE_FMT_FLT:
        {
            float *volp = samples;
            float scale = audio_volume / 256.f;
            for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
                *volp++ *= scale;
            }
            break;
        }
        case AV_SAMPLE_FMT_DBL:
        {
            double *volp = samples;
            double scale = audio_volume / 256.;
            for (i = 0; i < (decoded_data_size / sizeof(*volp)); i++) {
                *volp++ *= scale;
            }
            break;
        }
        default:
            av_log(NULL, AV_LOG_FATAL,
                   "Audio volume adjustment on sample format %s is not supported.\n",
                   av_get_sample_fmt_name(ist->st->codec->sample_fmt));
            exit_program(1);
        }
    }

    rate_emu_sleep(ist);

    resample_changed = ist->resample_sample_fmt     != decoded_frame->format         ||
                       ist->resample_channels       != avctx->channels               ||
                       ist->resample_channel_layout != decoded_frame->channel_layout ||
                       ist->resample_sample_rate    != decoded_frame->sample_rate;
    if (resample_changed) {
        char layout1[64], layout2[64];

        if (!guess_input_channel_layout(ist)) {
            av_log(NULL, AV_LOG_FATAL, "Unable to find default channel "
                   "layout for Input Stream #%d.%d\n", ist->file_index,
                   ist->st->index);
            exit_program(1);
        }
        decoded_frame->channel_layout = avctx->channel_layout;

        av_get_channel_layout_string(layout1, sizeof(layout1), ist->resample_channels,
                                     ist->resample_channel_layout);
        av_get_channel_layout_string(layout2, sizeof(layout2), avctx->channels,
                                     decoded_frame->channel_layout);

        av_log(NULL, AV_LOG_INFO,
               "Input stream #%d:%d frame changed from rate:%d fmt:%s ch:%d chl:%s to rate:%d fmt:%s ch:%d chl:%s\n",
               ist->file_index, ist->st->index,
               ist->resample_sample_rate,  av_get_sample_fmt_name(ist->resample_sample_fmt),
               ist->resample_channels, layout1,
               decoded_frame->sample_rate, av_get_sample_fmt_name(decoded_frame->format),
               avctx->channels, layout2);

        ist->resample_sample_fmt     = decoded_frame->format;
        ist->resample_sample_rate    = decoded_frame->sample_rate;
        ist->resample_channel_layout = decoded_frame->channel_layout;
        ist->resample_channels       = avctx->channels;

        for (i = 0; i < nb_filtergraphs; i++)
            if (ist_in_filtergraph(filtergraphs[i], ist) &&
                configure_filtergraph(filtergraphs[i]) < 0) {
                av_log(NULL, AV_LOG_FATAL, "Error reinitializing filters!\n");
                exit_program(1);
            }
    }

    if (decoded_frame->pts != AV_NOPTS_VALUE)
        decoded_frame->pts = av_rescale_q(decoded_frame->pts,
                                          ist->st->time_base,
                                          (AVRational){1, ist->st->codec->sample_rate});
    for (i = 0; i < ist->nb_filters; i++)
        av_buffersrc_write_frame(ist->filters[i]->filter, decoded_frame);

    return ret;
}

static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output)
{
    AVFrame *decoded_frame;
    void *buffer_to_free = NULL;
    int i, ret = 0, resample_changed;
    float quality;

    if (!ist->decoded_frame && !(ist->decoded_frame = avcodec_alloc_frame()))
        return AVERROR(ENOMEM);
    else
        avcodec_get_frame_defaults(ist->decoded_frame);
    decoded_frame = ist->decoded_frame;

    ret = avcodec_decode_video2(ist->st->codec,
                                decoded_frame, got_output, pkt);
    if (!*got_output || ret < 0) {
        if (!pkt->size) {
            for (i = 0; i < ist->nb_filters; i++)
                av_buffersrc_buffer(ist->filters[i]->filter, NULL);
        }
        return ret;
    }

    quality = same_quant ? decoded_frame->quality : 0;
    decoded_frame->pts = guess_correct_pts(&ist->pts_ctx, decoded_frame->pkt_pts,
                                           decoded_frame->pkt_dts);
    pkt->size = 0;
    pre_process_video_frame(ist, (AVPicture *)decoded_frame, &buffer_to_free);

    rate_emu_sleep(ist);

    if (ist->st->sample_aspect_ratio.num)
        decoded_frame->sample_aspect_ratio = ist->st->sample_aspect_ratio;

    resample_changed = ist->resample_width   != decoded_frame->width  ||
                       ist->resample_height  != decoded_frame->height ||
                       ist->resample_pix_fmt != decoded_frame->format;
    if (resample_changed) {
        av_log(NULL, AV_LOG_INFO,
               "Input stream #%d:%d frame changed from size:%dx%d fmt:%s to size:%dx%d fmt:%s\n",
               ist->file_index, ist->st->index,
               ist->resample_width,  ist->resample_height,  av_get_pix_fmt_name(ist->resample_pix_fmt),
               decoded_frame->width, decoded_frame->height, av_get_pix_fmt_name(decoded_frame->format));

        ret = poll_filters();
        if (ret < 0 && (ret != AVERROR_EOF && ret != AVERROR(EAGAIN)))
            av_log(NULL, AV_LOG_ERROR, "Error while filtering.\n");

        ist->resample_width   = decoded_frame->width;
        ist->resample_height  = decoded_frame->height;
        ist->resample_pix_fmt = decoded_frame->format;

        for (i = 0; i < nb_filtergraphs; i++)
            if (ist_in_filtergraph(filtergraphs[i], ist) &&
                configure_filtergraph(filtergraphs[i]) < 0) {
                av_log(NULL, AV_LOG_FATAL, "Error reinitializing filters!\n");
                exit_program(1);
            }
    }

    for (i = 0; i < ist->nb_filters; i++) {
        // XXX what an ugly hack
        if (ist->filters[i]->graph->nb_outputs == 1)
            ist->filters[i]->graph->outputs[0]->ost->last_quality = quality;

        if (ist->st->codec->codec->capabilities & CODEC_CAP_DR1) {
            FrameBuffer      *buf = decoded_frame->opaque;
            AVFilterBufferRef *fb = avfilter_get_video_buffer_ref_from_arrays(
                                        decoded_frame->data, decoded_frame->linesize,
                                        AV_PERM_READ | AV_PERM_PRESERVE,
                                        ist->st->codec->width, ist->st->codec->height,
                                        ist->st->codec->pix_fmt);

            avfilter_copy_frame_props(fb, decoded_frame);
            fb->buf->priv           = buf;
            fb->buf->free           = filter_release_buffer;

            buf->refcount++;
            av_buffersrc_buffer(ist->filters[i]->filter, fb);
        } else
            av_buffersrc_write_frame(ist->filters[i]->filter, decoded_frame);
    }

    av_free(buffer_to_free);
    return ret;
}

static int transcode_subtitles(InputStream *ist, AVPacket *pkt, int *got_output)
{
    AVSubtitle subtitle;
    int i, ret = avcodec_decode_subtitle2(ist->st->codec,
                                          &subtitle, got_output, pkt);
    if (ret < 0)
        return ret;
    if (!*got_output)
        return ret;

    rate_emu_sleep(ist);

    for (i = 0; i < nb_output_streams; i++) {
        OutputStream *ost = output_streams[i];

        if (!check_output_constraints(ist, ost) || !ost->encoding_needed)
            continue;

        do_subtitle_out(output_files[ost->file_index]->ctx, ost, ist, &subtitle, pkt->pts);
    }

    avsubtitle_free(&subtitle);
    return ret;
}

/* pkt = NULL means EOF (needed to flush decoder buffers) */
static int output_packet(InputStream *ist, const AVPacket *pkt)
{
    int i;
    int got_output;
    AVPacket avpkt;

    if (ist->next_dts == AV_NOPTS_VALUE)
        ist->next_dts = ist->last_dts;

    if (pkt == NULL) {
        /* EOF handling */
        av_init_packet(&avpkt);
        avpkt.data = NULL;
        avpkt.size = 0;
        goto handle_eof;
    } else {
        avpkt = *pkt;
    }

    if (pkt->dts != AV_NOPTS_VALUE)
        ist->next_dts = ist->last_dts = av_rescale_q(pkt->dts, ist->st->time_base, AV_TIME_BASE_Q);

    // while we have more to decode or while the decoder did output something on EOF
    while (ist->decoding_needed && (avpkt.size > 0 || (!pkt && got_output))) {
        int ret = 0;
    handle_eof:

        ist->last_dts = ist->next_dts;

        if (avpkt.size && avpkt.size != pkt->size) {
            av_log(NULL, ist->showed_multi_packet_warning ? AV_LOG_VERBOSE : AV_LOG_WARNING,
                   "Multiple frames in a packet from stream %d\n", pkt->stream_index);
            ist->showed_multi_packet_warning = 1;
        }

        switch (ist->st->codec->codec_type) {
        case AVMEDIA_TYPE_AUDIO:
            ret = decode_audio    (ist, &avpkt, &got_output);
            break;
        case AVMEDIA_TYPE_VIDEO:
            ret = decode_video    (ist, &avpkt, &got_output);
            if (avpkt.duration)
                ist->next_dts += av_rescale_q(avpkt.duration, ist->st->time_base, AV_TIME_BASE_Q);
            else if (ist->st->avg_frame_rate.num)
                ist->next_dts += av_rescale_q(1, av_inv_q(ist->st->avg_frame_rate),
                                              AV_TIME_BASE_Q);
            else if (ist->st->codec->time_base.num != 0) {
                int ticks      = ist->st->parser ? ist->st->parser->repeat_pict + 1 :
                                                   ist->st->codec->ticks_per_frame;
                ist->next_dts += av_rescale_q(ticks, ist->st->codec->time_base, AV_TIME_BASE_Q);
            }
            break;
        case AVMEDIA_TYPE_SUBTITLE:
            ret = transcode_subtitles(ist, &avpkt, &got_output);
            break;
        default:
            return -1;
        }

        if (ret < 0)
            return ret;
        // touch data and size only if not EOF
        if (pkt) {
            avpkt.data += ret;
            avpkt.size -= ret;
        }
        if (!got_output) {
            continue;
        }
    }

    /* handle stream copy */
    if (!ist->decoding_needed) {
        rate_emu_sleep(ist);
        ist->last_dts = ist->next_dts;
        switch (ist->st->codec->codec_type) {
        case AVMEDIA_TYPE_AUDIO:
            ist->next_dts += ((int64_t)AV_TIME_BASE * ist->st->codec->frame_size) /
                             ist->st->codec->sample_rate;
            break;
        case AVMEDIA_TYPE_VIDEO:
            if (ist->st->codec->time_base.num != 0) {
                int ticks = ist->st->parser ? ist->st->parser->repeat_pict + 1 : ist->st->codec->ticks_per_frame;
                ist->next_dts += ((int64_t)AV_TIME_BASE *
                                  ist->st->codec->time_base.num * ticks) /
                                  ist->st->codec->time_base.den;
            }
            break;
        }
    }
    for (i = 0; pkt && i < nb_output_streams; i++) {
        OutputStream *ost = output_streams[i];

        if (!check_output_constraints(ist, ost) || ost->encoding_needed)
            continue;

        do_streamcopy(ist, ost, pkt);
    }

    return 0;
}

static void print_sdp(void)
{
    char sdp[2048];
    int i;
    AVFormatContext **avc = av_malloc(sizeof(*avc) * nb_output_files);

    if (!avc)
        exit_program(1);
    for (i = 0; i < nb_output_files; i++)
        avc[i] = output_files[i]->ctx;

    av_sdp_create(avc, nb_output_files, sdp, sizeof(sdp));
    printf("SDP:\n%s\n", sdp);
    fflush(stdout);
    av_freep(&avc);
}

static int init_input_stream(int ist_index, char *error, int error_len)
{
    int i;
    InputStream *ist = input_streams[ist_index];
    if (ist->decoding_needed) {
        AVCodec *codec = ist->dec;
        if (!codec) {
            snprintf(error, error_len, "Decoder (codec id %d) not found for input stream #%d:%d",
                    ist->st->codec->codec_id, ist->file_index, ist->st->index);
            return AVERROR(EINVAL);
        }

        /* update requested sample format for the decoder based on the
           corresponding encoder sample format */
        for (i = 0; i < nb_output_streams; i++) {
            OutputStream *ost = output_streams[i];
            if (ost->source_index == ist_index) {
                update_sample_fmt(ist->st->codec, codec, ost->st->codec);
                break;
            }
        }

        if (codec->type == AVMEDIA_TYPE_VIDEO && codec->capabilities & CODEC_CAP_DR1) {
            ist->st->codec->get_buffer     = codec_get_buffer;
            ist->st->codec->release_buffer = codec_release_buffer;
            ist->st->codec->opaque         = &ist->buffer_pool;
        }

        if (!av_dict_get(ist->opts, "threads", NULL, 0))
            av_dict_set(&ist->opts, "threads", "auto", 0);
        if (avcodec_open2(ist->st->codec, codec, &ist->opts) < 0) {
            snprintf(error, error_len, "Error while opening decoder for input stream #%d:%d",
                    ist->file_index, ist->st->index);
            return AVERROR(EINVAL);
        }
        assert_codec_experimental(ist->st->codec, 0);
        assert_avoptions(ist->opts);
    }

    ist->last_dts = ist->st->avg_frame_rate.num ? - ist->st->codec->has_b_frames * AV_TIME_BASE / av_q2d(ist->st->avg_frame_rate) : 0;
    ist->next_dts = AV_NOPTS_VALUE;
    init_pts_correction(&ist->pts_ctx);
    ist->is_start = 1;

    return 0;
}

static InputStream *get_input_stream(OutputStream *ost)
{
    if (ost->source_index >= 0)
        return input_streams[ost->source_index];

    if (ost->filter) {
        FilterGraph *fg = ost->filter->graph;
        int i;

        for (i = 0; i < fg->nb_inputs; i++)
            if (fg->inputs[i]->ist->st->codec->codec_type == ost->st->codec->codec_type)
                return fg->inputs[i]->ist;
    }

    return NULL;
}

static void parse_forced_key_frames(char *kf, OutputStream *ost,
                                    AVCodecContext *avctx)
{
    char *p;
    int n = 1, i;
    int64_t t;

    for (p = kf; *p; p++)
        if (*p == ',')
            n++;
    ost->forced_kf_count = n;
    ost->forced_kf_pts   = av_malloc(sizeof(*ost->forced_kf_pts) * n);
    if (!ost->forced_kf_pts) {
        av_log(NULL, AV_LOG_FATAL, "Could not allocate forced key frames array.\n");
        exit_program(1);
    }

    p = kf;
    for (i = 0; i < n; i++) {
        char *next = strchr(p, ',');

        if (next)
            *next++ = 0;

        t = parse_time_or_die("force_key_frames", p, 1);
        ost->forced_kf_pts[i] = av_rescale_q(t, AV_TIME_BASE_Q, avctx->time_base);

        p = next;
    }
}

static int transcode_init(void)
{
    int ret = 0, i, j, k;
    AVFormatContext *oc;
    AVCodecContext *codec;
    OutputStream *ost;
    InputStream *ist;
    char error[1024];
    int want_sdp = 1;

    /* init framerate emulation */
    for (i = 0; i < nb_input_files; i++) {
        InputFile *ifile = input_files[i];
        if (ifile->rate_emu)
            for (j = 0; j < ifile->nb_streams; j++)
                input_streams[j + ifile->ist_index]->start = av_gettime();
    }

    /* output stream init */
    for (i = 0; i < nb_output_files; i++) {
        oc = output_files[i]->ctx;
        if (!oc->nb_streams && !(oc->oformat->flags & AVFMT_NOSTREAMS)) {
            av_dump_format(oc, i, oc->filename, 1);
            av_log(NULL, AV_LOG_ERROR, "Output file #%d does not contain any stream\n", i);
            return AVERROR(EINVAL);
        }
    }

    /* init complex filtergraphs */
    for (i = 0; i < nb_filtergraphs; i++)
        if ((ret = avfilter_graph_config(filtergraphs[i]->graph, NULL)) < 0)
            return ret;

    /* for each output stream, we compute the right encoding parameters */
    for (i = 0; i < nb_output_streams; i++) {
        AVCodecContext *icodec = NULL;
        ost = output_streams[i];
        oc  = output_files[ost->file_index]->ctx;
        ist = get_input_stream(ost);

        if (ost->attachment_filename)
            continue;

        codec  = ost->st->codec;

        if (ist) {
            icodec = ist->st->codec;

            ost->st->disposition          = ist->st->disposition;
            codec->bits_per_raw_sample    = icodec->bits_per_raw_sample;
            codec->chroma_sample_location = icodec->chroma_sample_location;
        }

        if (ost->stream_copy) {
            uint64_t extra_size;

            av_assert0(ist && !ost->filter);

            extra_size = (uint64_t)icodec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE;

            if (extra_size > INT_MAX) {
                return AVERROR(EINVAL);
            }

            /* if stream_copy is selected, no need to decode or encode */
            codec->codec_id   = icodec->codec_id;
            codec->codec_type = icodec->codec_type;

            if (!codec->codec_tag) {
                if (!oc->oformat->codec_tag ||
                     av_codec_get_id (oc->oformat->codec_tag, icodec->codec_tag) == codec->codec_id ||
                     av_codec_get_tag(oc->oformat->codec_tag, icodec->codec_id) <= 0)
                    codec->codec_tag = icodec->codec_tag;
            }

            codec->bit_rate       = icodec->bit_rate;
            codec->rc_max_rate    = icodec->rc_max_rate;
            codec->rc_buffer_size = icodec->rc_buffer_size;
            codec->field_order    = icodec->field_order;
            codec->extradata      = av_mallocz(extra_size);
            if (!codec->extradata) {
                return AVERROR(ENOMEM);
            }
            memcpy(codec->extradata, icodec->extradata, icodec->extradata_size);
            codec->extradata_size = icodec->extradata_size;
            if (!copy_tb) {
                codec->time_base      = icodec->time_base;
                codec->time_base.num *= icodec->ticks_per_frame;
                av_reduce(&codec->time_base.num, &codec->time_base.den,
                          codec->time_base.num, codec->time_base.den, INT_MAX);
            } else
                codec->time_base = ist->st->time_base;

            switch (codec->codec_type) {
            case AVMEDIA_TYPE_AUDIO:
                if (audio_volume != 256) {
                    av_log(NULL, AV_LOG_FATAL, "-acodec copy and -vol are incompatible (frames are not decoded)\n");
                    exit_program(1);
                }
                codec->channel_layout     = icodec->channel_layout;
                codec->sample_rate        = icodec->sample_rate;
                codec->channels           = icodec->channels;
                codec->frame_size         = icodec->frame_size;
                codec->audio_service_type = icodec->audio_service_type;
                codec->block_align        = icodec->block_align;
                break;
            case AVMEDIA_TYPE_VIDEO:
                codec->pix_fmt            = icodec->pix_fmt;
                codec->width              = icodec->width;
                codec->height             = icodec->height;
                codec->has_b_frames       = icodec->has_b_frames;
                if (!codec->sample_aspect_ratio.num) {
                    codec->sample_aspect_ratio   =
                    ost->st->sample_aspect_ratio =
                        ist->st->sample_aspect_ratio.num ? ist->st->sample_aspect_ratio :
                        ist->st->codec->sample_aspect_ratio.num ?
                        ist->st->codec->sample_aspect_ratio : (AVRational){0, 1};
                }
                break;
            case AVMEDIA_TYPE_SUBTITLE:
                codec->width  = icodec->width;
                codec->height = icodec->height;
                break;
            case AVMEDIA_TYPE_DATA:
            case AVMEDIA_TYPE_ATTACHMENT:
                break;
            default:
                abort();
            }
        } else {
            if (!ost->enc) {
                /* should only happen when a default codec is not present. */
                snprintf(error, sizeof(error), "Automatic encoder selection "
                         "failed for output stream #%d:%d. Default encoder for "
                         "format %s is probably disabled. Please choose an "
                         "encoder manually.\n", ost->file_index, ost->index,
                         oc->oformat->name);
                ret = AVERROR(EINVAL);
                goto dump_format;
            }

            if (ist)
                ist->decoding_needed = 1;
            ost->encoding_needed = 1;

            /*
             * We want CFR output if and only if one of those is true:
             * 1) user specified output framerate with -r
             * 2) user specified -vsync cfr
             * 3) output format is CFR and the user didn't force vsync to
             *    something else than CFR
             *
             * in such a case, set ost->frame_rate
             */
            if (codec->codec_type == AVMEDIA_TYPE_VIDEO &&
                !ost->frame_rate.num && ist &&
                (video_sync_method ==  VSYNC_CFR ||
                 (video_sync_method ==  VSYNC_AUTO &&
                  !(oc->oformat->flags & (AVFMT_NOTIMESTAMPS | AVFMT_VARIABLE_FPS))))) {
                ost->frame_rate = ist->framerate.num ? ist->framerate :
                                  ist->st->avg_frame_rate.num ?
                                  ist->st->avg_frame_rate :
                                  (AVRational){25, 1};

                if (ost->enc && ost->enc->supported_framerates && !ost->force_fps) {
                    int idx = av_find_nearest_q_idx(ost->frame_rate, ost->enc->supported_framerates);
                    ost->frame_rate = ost->enc->supported_framerates[idx];
                }
            }

            if (!ost->filter &&
                (codec->codec_type == AVMEDIA_TYPE_VIDEO ||
                 codec->codec_type == AVMEDIA_TYPE_AUDIO)) {
                    FilterGraph *fg;
                    fg = init_simple_filtergraph(ist, ost);
                    if (configure_filtergraph(fg)) {
                        av_log(NULL, AV_LOG_FATAL, "Error opening filters!\n");
                        exit(1);
                    }
            }

            switch (codec->codec_type) {
            case AVMEDIA_TYPE_AUDIO:
                codec->sample_fmt     = ost->filter->filter->inputs[0]->format;
                codec->sample_rate    = ost->filter->filter->inputs[0]->sample_rate;
                codec->channel_layout = ost->filter->filter->inputs[0]->channel_layout;
                codec->channels       = av_get_channel_layout_nb_channels(codec->channel_layout);
                codec->time_base      = (AVRational){ 1, codec->sample_rate };
                break;
            case AVMEDIA_TYPE_VIDEO:
                codec->time_base = ost->filter->filter->inputs[0]->time_base;

                codec->width  = ost->filter->filter->inputs[0]->w;
                codec->height = ost->filter->filter->inputs[0]->h;
                codec->sample_aspect_ratio = ost->st->sample_aspect_ratio =
                    ost->frame_aspect_ratio ? // overridden by the -aspect cli option
                    av_d2q(ost->frame_aspect_ratio * codec->height/codec->width, 255) :
                    ost->filter->filter->inputs[0]->sample_aspect_ratio;
                codec->pix_fmt = ost->filter->filter->inputs[0]->format;

                if (icodec &&
                    (codec->width   != icodec->width  ||
                     codec->height  != icodec->height ||
                     codec->pix_fmt != icodec->pix_fmt)) {
                    codec->bits_per_raw_sample = 0;
                }

                if (ost->forced_keyframes)
                    parse_forced_key_frames(ost->forced_keyframes, ost,
                                            ost->st->codec);
                break;
            case AVMEDIA_TYPE_SUBTITLE:
                codec->time_base = (AVRational){1, 1000};
                break;
            default:
                abort();
                break;
            }
            /* two pass mode */
            if ((codec->flags & (CODEC_FLAG_PASS1 | CODEC_FLAG_PASS2))) {
                char logfilename[1024];
                FILE *f;

                snprintf(logfilename, sizeof(logfilename), "%s-%d.log",
                         ost->logfile_prefix ? ost->logfile_prefix :
                                               DEFAULT_PASS_LOGFILENAME_PREFIX,
                         i);
                if (!strcmp(ost->enc->name, "libx264")) {
                    av_dict_set(&ost->opts, "stats", logfilename, AV_DICT_DONT_OVERWRITE);
                } else {
                    if (codec->flags & CODEC_FLAG_PASS1) {
                        f = fopen(logfilename, "wb");
                        if (!f) {
                            av_log(NULL, AV_LOG_FATAL, "Cannot write log file '%s' for pass-1 encoding: %s\n",
                                   logfilename, strerror(errno));
                            exit_program(1);
                        }
                        ost->logfile = f;
                    } else {
                        char  *logbuffer;
                        size_t logbuffer_size;
                        if (cmdutils_read_file(logfilename, &logbuffer, &logbuffer_size) < 0) {
                            av_log(NULL, AV_LOG_FATAL, "Error reading log file '%s' for pass-2 encoding\n",
                                   logfilename);
                            exit_program(1);
                        }
                        codec->stats_in = logbuffer;
                    }
                }
            }
        }
    }

    /* open each encoder */
    for (i = 0; i < nb_output_streams; i++) {
        ost = output_streams[i];
        if (ost->encoding_needed) {
            AVCodec      *codec = ost->enc;
            AVCodecContext *dec = NULL;

            if ((ist = get_input_stream(ost)))
                dec = ist->st->codec;
            if (dec && dec->subtitle_header) {
                ost->st->codec->subtitle_header = av_malloc(dec->subtitle_header_size);
                if (!ost->st->codec->subtitle_header) {
                    ret = AVERROR(ENOMEM);
                    goto dump_format;
                }
                memcpy(ost->st->codec->subtitle_header, dec->subtitle_header, dec->subtitle_header_size);
                ost->st->codec->subtitle_header_size = dec->subtitle_header_size;
            }
            if (!av_dict_get(ost->opts, "threads", NULL, 0))
                av_dict_set(&ost->opts, "threads", "auto", 0);
            if (avcodec_open2(ost->st->codec, codec, &ost->opts) < 0) {
                snprintf(error, sizeof(error), "Error while opening encoder for output stream #%d:%d - maybe incorrect parameters such as bit_rate, rate, width or height",
                        ost->file_index, ost->index);
                ret = AVERROR(EINVAL);
                goto dump_format;
            }
            assert_codec_experimental(ost->st->codec, 1);
            assert_avoptions(ost->opts);
            if (ost->st->codec->bit_rate && ost->st->codec->bit_rate < 1000)
                av_log(NULL, AV_LOG_WARNING, "The bitrate parameter is set too low."
                                             "It takes bits/s as argument, not kbits/s\n");
            extra_size += ost->st->codec->extradata_size;

            if (ost->st->codec->me_threshold)
                input_streams[ost->source_index]->st->codec->debug |= FF_DEBUG_MV;
        }
    }

    /* init input streams */
    for (i = 0; i < nb_input_streams; i++)
        if ((ret = init_input_stream(i, error, sizeof(error))) < 0)
            goto dump_format;

    /* discard unused programs */
    for (i = 0; i < nb_input_files; i++) {
        InputFile *ifile = input_files[i];
        for (j = 0; j < ifile->ctx->nb_programs; j++) {
            AVProgram *p = ifile->ctx->programs[j];
            int discard  = AVDISCARD_ALL;

            for (k = 0; k < p->nb_stream_indexes; k++)
                if (!input_streams[ifile->ist_index + p->stream_index[k]]->discard) {
                    discard = AVDISCARD_DEFAULT;
                    break;
                }
            p->discard = discard;
        }
    }

    /* open files and write file headers */
    for (i = 0; i < nb_output_files; i++) {
        oc = output_files[i]->ctx;
        oc->interrupt_callback = int_cb;
        if ((ret = avformat_write_header(oc, &output_files[i]->opts)) < 0) {
            char errbuf[128];
            const char *errbuf_ptr = errbuf;
            if (av_strerror(ret, errbuf, sizeof(errbuf)) < 0)
                errbuf_ptr = strerror(AVUNERROR(ret));
            snprintf(error, sizeof(error), "Could not write header for output file #%d (incorrect codec parameters ?): %s", i, errbuf_ptr);
            ret = AVERROR(EINVAL);
            goto dump_format;
        }
        assert_avoptions(output_files[i]->opts);
        if (strcmp(oc->oformat->name, "rtp")) {
            want_sdp = 0;
        }
    }

 dump_format:
    /* dump the file output parameters - cannot be done before in case
       of stream copy */
    for (i = 0; i < nb_output_files; i++) {
        av_dump_format(output_files[i]->ctx, i, output_files[i]->ctx->filename, 1);
    }

    /* dump the stream mapping */
    av_log(NULL, AV_LOG_INFO, "Stream mapping:\n");
    for (i = 0; i < nb_input_streams; i++) {
        ist = input_streams[i];

        for (j = 0; j < ist->nb_filters; j++) {
            if (ist->filters[j]->graph->graph_desc) {
                av_log(NULL, AV_LOG_INFO, "  Stream #%d:%d (%s) -> %s",
                       ist->file_index, ist->st->index, ist->dec ? ist->dec->name : "?",
                       ist->filters[j]->name);
                if (nb_filtergraphs > 1)
                    av_log(NULL, AV_LOG_INFO, " (graph %d)", ist->filters[j]->graph->index);
                av_log(NULL, AV_LOG_INFO, "\n");
            }
        }
    }

    for (i = 0; i < nb_output_streams; i++) {
        ost = output_streams[i];

        if (ost->attachment_filename) {
            /* an attached file */
            av_log(NULL, AV_LOG_INFO, "  File %s -> Stream #%d:%d\n",
                   ost->attachment_filename, ost->file_index, ost->index);
            continue;
        }

        if (ost->filter && ost->filter->graph->graph_desc) {
            /* output from a complex graph */
            av_log(NULL, AV_LOG_INFO, "  %s", ost->filter->name);
            if (nb_filtergraphs > 1)
                av_log(NULL, AV_LOG_INFO, " (graph %d)", ost->filter->graph->index);

            av_log(NULL, AV_LOG_INFO, " -> Stream #%d:%d (%s)\n", ost->file_index,
                   ost->index, ost->enc ? ost->enc->name : "?");
            continue;
        }

        av_log(NULL, AV_LOG_INFO, "  Stream #%d:%d -> #%d:%d",
               input_streams[ost->source_index]->file_index,
               input_streams[ost->source_index]->st->index,
               ost->file_index,
               ost->index);
        if (ost->sync_ist != input_streams[ost->source_index])
            av_log(NULL, AV_LOG_INFO, " [sync #%d:%d]",
                   ost->sync_ist->file_index,
                   ost->sync_ist->st->index);
        if (ost->stream_copy)
            av_log(NULL, AV_LOG_INFO, " (copy)");
        else
            av_log(NULL, AV_LOG_INFO, " (%s -> %s)", input_streams[ost->source_index]->dec ?
                   input_streams[ost->source_index]->dec->name : "?",
                   ost->enc ? ost->enc->name : "?");
        av_log(NULL, AV_LOG_INFO, "\n");
    }

    if (ret) {
        av_log(NULL, AV_LOG_ERROR, "%s\n", error);
        return ret;
    }

    if (want_sdp) {
        print_sdp();
    }

    return 0;
}

/**
 * @return 1 if there are still streams where more output is wanted,
 *         0 otherwise
 */
static int need_output(void)
{
    int i;

    for (i = 0; i < nb_output_streams; i++) {
        OutputStream *ost    = output_streams[i];
        OutputFile *of       = output_files[ost->file_index];
        AVFormatContext *os  = output_files[ost->file_index]->ctx;

        if (ost->finished ||
            (os->pb && avio_tell(os->pb) >= of->limit_filesize))
            continue;
        if (ost->frame_number >= ost->max_frames) {
            int j;
            for (j = 0; j < of->ctx->nb_streams; j++)
                output_streams[of->ost_index + j]->finished = 1;
            continue;
        }

        return 1;
    }

    return 0;
}

static InputFile *select_input_file(void)
{
    InputFile *ifile = NULL;
    int64_t ipts_min = INT64_MAX;
    int i;

    for (i = 0; i < nb_input_streams; i++) {
        InputStream *ist = input_streams[i];
        int64_t ipts     = ist->last_dts;

        if (ist->discard || input_files[ist->file_index]->eagain)
            continue;
        if (!input_files[ist->file_index]->eof_reached) {
            if (ipts < ipts_min) {
                ipts_min = ipts;
                ifile    = input_files[ist->file_index];
            }
        }
    }

    return ifile;
}

#if HAVE_PTHREADS
static void *input_thread(void *arg)
{
    InputFile *f = arg;
    int ret = 0;

    while (!transcoding_finished && ret >= 0) {
        AVPacket pkt;
        ret = av_read_frame(f->ctx, &pkt);

        if (ret == AVERROR(EAGAIN)) {
            av_usleep(10000);