avconv.c

                codec->height = icodec->height;
                break;
            case AVMEDIA_TYPE_DATA:
                break;
            default:
                abort();
            }
        } else {
            if (!ost->enc)
                ost->enc = avcodec_find_encoder(ost->st->codec->codec_id);
            switch(codec->codec_type) {
            case AVMEDIA_TYPE_AUDIO:
                ost->fifo= av_fifo_alloc(1024);
                if (!ost->fifo) {
                    return AVERROR(ENOMEM);
                }
                ost->reformat_pair = MAKE_SFMT_PAIR(AV_SAMPLE_FMT_NONE,AV_SAMPLE_FMT_NONE);
                if (!codec->sample_rate) {
                    codec->sample_rate = icodec->sample_rate;
                    if (icodec->lowres)
                        codec->sample_rate >>= icodec->lowres;
                }
                choose_sample_rate(ost->st, ost->enc);
                codec->time_base = (AVRational){1, codec->sample_rate};
                if (codec->sample_fmt == AV_SAMPLE_FMT_NONE)
                    codec->sample_fmt = icodec->sample_fmt;
                choose_sample_fmt(ost->st, ost->enc);
                if (!codec->channels)
                    codec->channels = icodec->channels;
                codec->channel_layout = icodec->channel_layout;
                if (av_get_channel_layout_nb_channels(codec->channel_layout) != codec->channels)
                    codec->channel_layout = 0;
                ost->audio_resample = codec->sample_rate != icodec->sample_rate || audio_sync_method > 1;
                icodec->request_channels = codec->channels;
                ist->decoding_needed = 1;
                ost->encoding_needed = 1;
                ost->resample_sample_fmt  = icodec->sample_fmt;
                ost->resample_sample_rate = icodec->sample_rate;
                ost->resample_channels    = icodec->channels;
                break;
            case AVMEDIA_TYPE_VIDEO:
                if (codec->pix_fmt == PIX_FMT_NONE)
                    codec->pix_fmt = icodec->pix_fmt;
                choose_pixel_fmt(ost->st, ost->enc);

                if (ost->st->codec->pix_fmt == PIX_FMT_NONE) {
                    fprintf(stderr, "Video pixel format is unknown, stream cannot be encoded\n");
                    exit_program(1);
                }

                if (!codec->width || !codec->height) {
                    codec->width  = icodec->width;
                    codec->height = icodec->height;
                }

                ost->video_resample = codec->width   != icodec->width  ||
                                      codec->height  != icodec->height ||
                                      codec->pix_fmt != icodec->pix_fmt;
                if (ost->video_resample) {
#if !CONFIG_AVFILTER
                    avcodec_get_frame_defaults(&ost->pict_tmp);
                    if(avpicture_alloc((AVPicture*)&ost->pict_tmp, codec->pix_fmt,
                                       codec->width, codec->height)) {
                        fprintf(stderr, "Cannot allocate temp picture, check pix fmt\n");
                        exit_program(1);
                    }
                    ost->img_resample_ctx = sws_getContext(
                        icodec->width,
                        icodec->height,
                        icodec->pix_fmt,
                        codec->width,
                        codec->height,
                        codec->pix_fmt,
                        ost->sws_flags, NULL, NULL, NULL);
                    if (ost->img_resample_ctx == NULL) {
                        fprintf(stderr, "Cannot get resampling context\n");
                        exit_program(1);
                    }
#endif
                    codec->bits_per_raw_sample= 0;
                }

                ost->resample_height = icodec->height;
                ost->resample_width  = icodec->width;
                ost->resample_pix_fmt= icodec->pix_fmt;
                ost->encoding_needed = 1;
                ist->decoding_needed = 1;

                if (!ost->frame_rate.num)
                    ost->frame_rate = ist->st->r_frame_rate.num ? ist->st->r_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];
                }
                codec->time_base = (AVRational){ost->frame_rate.den, ost->frame_rate.num};

#if CONFIG_AVFILTER
                if (configure_video_filters(ist, ost)) {
                    fprintf(stderr, "Error opening filters!\n");
                    exit(1);
                }
#endif
                break;
            case AVMEDIA_TYPE_SUBTITLE:
                ost->encoding_needed = 1;
                ist->decoding_needed = 1;
                break;
            default:
                abort();
                break;
            }
            /* two pass mode */
            if (ost->encoding_needed &&
                (codec->flags & (CODEC_FLAG_PASS1 | CODEC_FLAG_PASS2))) {
                char logfilename[1024];
                FILE *f;

                snprintf(logfilename, sizeof(logfilename), "%s-%d.log",
                         pass_logfilename_prefix ? pass_logfilename_prefix : DEFAULT_PASS_LOGFILENAME_PREFIX,
                         i);
                if (codec->flags & CODEC_FLAG_PASS1) {
                    f = fopen(logfilename, "wb");
                    if (!f) {
                        fprintf(stderr, "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 (read_file(logfilename, &logbuffer, &logbuffer_size) < 0) {
                        fprintf(stderr, "Error reading log file '%s' for pass-2 encoding\n", logfilename);
                        exit_program(1);
                    }
                    codec->stats_in = logbuffer;
                }
            }
        }
        if(codec->codec_type == AVMEDIA_TYPE_VIDEO){
            int size= codec->width * codec->height;
            bit_buffer_size= FFMAX(bit_buffer_size, 6*size + 200);
        }
    }

    if (!bit_buffer)
        bit_buffer = av_malloc(bit_buffer_size);
    if (!bit_buffer) {
        fprintf(stderr, "Cannot allocate %d bytes output buffer\n",
                bit_buffer_size);
        return AVERROR(ENOMEM);
    }

    /* 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 = input_streams[ost->source_index].st->codec;
            if (!codec) {
                snprintf(error, sizeof(error), "Encoder (codec id %d) not found for output stream #%d.%d",
                         ost->st->codec->codec_id, ost->file_index, ost->index);
                ret = AVERROR(EINVAL);
                goto dump_format;
            }
            if (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 (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, output_streams, nb_output_streams, 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++) {
        os = output_files[i].ctx;
        if (avformat_write_header(os, &output_files[i].opts) < 0) {
            snprintf(error, sizeof(error), "Could not write header for output file #%d (incorrect codec parameters ?)", i);
            ret = AVERROR(EINVAL);
            goto dump_format;
        }
        assert_avoptions(output_files[i].opts);
        if (strcmp(os->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 */
    if (verbose >= 0) {
        fprintf(stderr, "Stream mapping:\n");
        for (i = 0; i < nb_output_streams;i ++) {
            ost = &output_streams[i];
            fprintf(stderr, "  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])
                fprintf(stderr, " [sync #%d.%d]",
                        ost->sync_ist->file_index,
                        ost->sync_ist->st->index);
            if (ost->st->stream_copy)
                fprintf(stderr, " (copy)");
            else
                fprintf(stderr, " (%s -> %s)", input_streams[ost->source_index].dec ?
                        input_streams[ost->source_index].dec->name : "?",
                        ost->enc ? ost->enc->name : "?");
            fprintf(stderr, "\n");
        }
    }

    if (ret) {
        fprintf(stderr, "%s\n", error);
        return ret;
    }

    if (want_sdp) {
        print_sdp(output_files, nb_output_files);
    }

    return 0;
}

/*
 * The following code is the main loop of the file converter
 */
static int transcode(OutputFile *output_files,
                     int nb_output_files,
                     InputFile *input_files,
                     int nb_input_files)
{
    int ret, i;
    AVFormatContext *is, *os;
    OutputStream *ost;
    InputStream *ist;
    uint8_t *no_packet;
    int no_packet_count=0;
    int64_t timer_start;

    if (!(no_packet = av_mallocz(nb_input_files)))
        exit_program(1);

    ret = transcode_init(output_files, nb_output_files, input_files, nb_input_files);
    if (ret < 0)
        goto fail;

    if (verbose >= 0)
        fprintf(stderr, "Press ctrl-c to stop encoding\n");
    term_init();

    timer_start = av_gettime();

    for(; received_sigterm == 0;) {
        int file_index, ist_index;
        AVPacket pkt;
        int64_t ipts_min;
        double opts_min;

        ipts_min = INT64_MAX;
        opts_min= 1e100;

        /* select the stream that we must read now by looking at the
           smallest output pts */
        file_index = -1;
        for (i = 0; i < nb_output_streams; i++) {
            OutputFile *of;
            int64_t ipts;
            double  opts;
            ost = &output_streams[i];
            of = &output_files[ost->file_index];
            os = output_files[ost->file_index].ctx;
            ist = &input_streams[ost->source_index];
            if (ost->is_past_recording_time || no_packet[ist->file_index] ||
                (os->pb && avio_tell(os->pb) >= of->limit_filesize))
                continue;
            opts = ost->st->pts.val * av_q2d(ost->st->time_base);
            ipts = ist->pts;
            if (!input_files[ist->file_index].eof_reached){
                if(ipts < ipts_min) {
                    ipts_min = ipts;
                    if(input_sync ) file_index = ist->file_index;
                }
                if(opts < opts_min) {
                    opts_min = opts;
                    if(!input_sync) file_index = ist->file_index;
                }
            }
            if (ost->frame_number >= ost->max_frames) {
                int j;
                for (j = 0; j < of->ctx->nb_streams; j++)
                    output_streams[of->ost_index + j].is_past_recording_time = 1;
                continue;
            }
        }
        /* if none, if is finished */
        if (file_index < 0) {
            if(no_packet_count){
                no_packet_count=0;
                memset(no_packet, 0, nb_input_files);
                usleep(10000);
                continue;
            }
            break;
        }

        /* read a frame from it and output it in the fifo */
        is = input_files[file_index].ctx;
        ret= av_read_frame(is, &pkt);
        if(ret == AVERROR(EAGAIN)){
            no_packet[file_index]=1;
            no_packet_count++;
            continue;
        }
        if (ret < 0) {
            input_files[file_index].eof_reached = 1;
            if (opt_shortest)
                break;
            else
                continue;
        }

        no_packet_count=0;
        memset(no_packet, 0, nb_input_files);

        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 >= input_files[file_index].nb_streams)
            goto discard_packet;
        ist_index = input_files[file_index].ist_index + pkt.stream_index;
        ist = &input_streams[ist_index];
        if (ist->discard)
            goto discard_packet;

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

//        fprintf(stderr, "next:%"PRId64" dts:%"PRId64" off:%"PRId64" %d\n", ist->next_pts, pkt.dts, input_files[ist->file_index].ts_offset, ist->st->codec->codec_type);
        if (pkt.dts != AV_NOPTS_VALUE && ist->next_pts != AV_NOPTS_VALUE
            && (is->iformat->flags & AVFMT_TS_DISCONT)) {
            int64_t pkt_dts= av_rescale_q(pkt.dts, ist->st->time_base, AV_TIME_BASE_Q);
            int64_t delta= pkt_dts - ist->next_pts;
            if((FFABS(delta) > 1LL*dts_delta_threshold*AV_TIME_BASE || pkt_dts+1<ist->pts)&& !copy_ts){
                input_files[ist->file_index].ts_offset -= delta;
                if (verbose > 2)
                    fprintf(stderr, "timestamp discontinuity %"PRId64", new offset= %"PRId64"\n",
                            delta, input_files[ist->file_index].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);
            }
        }

        //fprintf(stderr,"read #%d.%d size=%d\n", ist->file_index, ist->st->index, pkt.size);
        if (output_packet(ist, ist_index, output_streams, nb_output_streams, &pkt) < 0) {

            if (verbose >= 0)
                fprintf(stderr, "Error while decoding stream #%d.%d\n",
                        ist->file_index, ist->st->index);
            if (exit_on_error)
                exit_program(1);
            av_free_packet(&pkt);
            continue;
        }

    discard_packet:
        av_free_packet(&pkt);

        /* dump report by using the output first video and audio streams */
        print_report(output_files, output_streams, nb_output_streams, 0, timer_start);
    }

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

    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(output_files, output_streams, nb_output_streams, 1, timer_start);

    /* 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);
        }
#if CONFIG_AVFILTER
        avfilter_graph_free(&ost->graph);
#endif
    }

    /* 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:
    av_freep(&bit_buffer);
    av_freep(&no_packet);

    if (output_streams) {
        for (i = 0; i < nb_output_streams; i++) {
            ost = &output_streams[i];
            if (ost) {
                if (ost->st->stream_copy)
                    av_freep(&ost->st->codec->extradata);
                if (ost->logfile) {
                    fclose(ost->logfile);
                    ost->logfile = NULL;
                }
                av_fifo_free(ost->fifo); /* works even if fifo is not
                                             initialized but set to zero */
                av_freep(&ost->st->codec->subtitle_header);
                av_free(ost->pict_tmp.data[0]);
                av_free(ost->forced_kf_pts);
                if (ost->video_resample)
                    sws_freeContext(ost->img_resample_ctx);
                if (ost->resample)
                    audio_resample_close(ost->resample);
                if (ost->reformat_ctx)
                    av_audio_convert_free(ost->reformat_ctx);
                av_dict_free(&ost->opts);
            }
        }
    }
    return ret;
}

static int opt_verbose(const char *opt, const char *arg)
{
    verbose = parse_number_or_die(opt, arg, OPT_INT64, -10, 10);
    return 0;
}

static double parse_frame_aspect_ratio(const char *arg)
{
    int x = 0, y = 0;
    double ar = 0;
    const char *p;
    char *end;

    p = strchr(arg, ':');
    if (p) {
        x = strtol(arg, &end, 10);
        if (end == p)
            y = strtol(end+1, &end, 10);
        if (x > 0 && y > 0)
            ar = (double)x / (double)y;
    } else
        ar = strtod(arg, NULL);

    if (!ar) {
        fprintf(stderr, "Incorrect aspect ratio specification.\n");
        exit_program(1);
    }
    return ar;
}

static int opt_audio_codec(OptionsContext *o, const char *opt, const char *arg)
{
    return parse_option(o, "codec:a", arg, options);
}

static int opt_video_codec(OptionsContext *o, const char *opt, const char *arg)
{
    return parse_option(o, "codec:v", arg, options);
}

static int opt_subtitle_codec(OptionsContext *o, const char *opt, const char *arg)
{
    return parse_option(o, "codec:s", arg, options);
}

static int opt_data_codec(OptionsContext *o, const char *opt, const char *arg)
{
    return parse_option(o, "codec:d", arg, options);
}

static int opt_map(OptionsContext *o, const char *opt, const char *arg)
{
    StreamMap *m = NULL;
    int i, negative = 0, file_idx;
    int sync_file_idx = -1, sync_stream_idx;
    char *p, *sync;
    char *map;

    if (*arg == '-') {
        negative = 1;
        arg++;
    }
    map = av_strdup(arg);

    /* parse sync stream first, just pick first matching stream */
    if (sync = strchr(map, ',')) {
        *sync = 0;
        sync_file_idx = strtol(sync + 1, &sync, 0);
        if (sync_file_idx >= nb_input_files || sync_file_idx < 0) {
            av_log(NULL, AV_LOG_FATAL, "Invalid sync file index: %d.\n", sync_file_idx);
            exit_program(1);
        }
        if (*sync)
            sync++;
        for (i = 0; i < input_files[sync_file_idx].nb_streams; i++)
            if (check_stream_specifier(input_files[sync_file_idx].ctx,
                                       input_files[sync_file_idx].ctx->streams[i], sync) == 1) {
                sync_stream_idx = i;
                break;
            }
        if (i == input_files[sync_file_idx].nb_streams) {
            av_log(NULL, AV_LOG_FATAL, "Sync stream specification in map %s does not "
                                       "match any streams.\n", arg);
            exit_program(1);
        }
    }


    file_idx = strtol(map, &p, 0);
    if (file_idx >= nb_input_files || file_idx < 0) {
        av_log(NULL, AV_LOG_FATAL, "Invalid input file index: %d.\n", file_idx);
        exit_program(1);
    }
    if (negative)
        /* disable some already defined maps */
        for (i = 0; i < o->nb_stream_maps; i++) {
            m = &o->stream_maps[i];
            if (check_stream_specifier(input_files[m->file_index].ctx,
                                       input_files[m->file_index].ctx->streams[m->stream_index],
                                       *p == ':' ? p + 1 : p) > 0)
                m->disabled = 1;
        }
    else
        for (i = 0; i < input_files[file_idx].nb_streams; i++) {
            if (check_stream_specifier(input_files[file_idx].ctx, input_files[file_idx].ctx->streams[i],
                        *p == ':' ? p + 1 : p) <= 0)
                continue;
            o->stream_maps = grow_array(o->stream_maps, sizeof(*o->stream_maps),
                                        &o->nb_stream_maps, o->nb_stream_maps + 1);
            m = &o->stream_maps[o->nb_stream_maps - 1];

            m->file_index   = file_idx;
            m->stream_index = i;

            if (sync_file_idx >= 0) {
                m->sync_file_index   = sync_file_idx;
                m->sync_stream_index = sync_stream_idx;
            } else {
                m->sync_file_index   = file_idx;
                m->sync_stream_index = i;
            }
        }

    if (!m) {
        av_log(NULL, AV_LOG_FATAL, "Stream map '%s' matches no streams.\n", arg);
        exit_program(1);
    }

    av_freep(&map);
    return 0;
}

static void parse_meta_type(char *arg, char *type, int *index)
{
    if (*arg) {
        *type = *arg;
        switch (*arg) {
        case 'g':
            break;
        case 's':
        case 'c':
        case 'p':
            if (*(++arg) == ':')
                *index = strtol(++arg, NULL, 0);
            break;
        default:
            fprintf(stderr, "Invalid metadata type %c.\n", *arg);
            exit_program(1);
        }
    } else
        *type = 'g';
}

static int opt_map_metadata(OptionsContext *o, const char *opt, const char *arg)
{
    MetadataMap *m, *m1;
    char *p;

    o->meta_data_maps = grow_array(o->meta_data_maps, sizeof(*o->meta_data_maps),
                                   &o->nb_meta_data_maps, o->nb_meta_data_maps + 1);

    m = &o->meta_data_maps[o->nb_meta_data_maps - 1][1];
    m->file = strtol(arg, &p, 0);
    parse_meta_type(*p ? p + 1 : p, &m->type, &m->index);

    m1 = &o->meta_data_maps[o->nb_meta_data_maps - 1][0];
    if (p = strchr(opt, ':'))
        parse_meta_type(p + 1, &m1->type, &m1->index);
    else
        m1->type = 'g';

    if (m->type == 'g' || m1->type == 'g')
        o->metadata_global_manual = 1;
    if (m->type == 's' || m1->type == 's')
        o->metadata_streams_manual = 1;
    if (m->type == 'c' || m1->type == 'c')
        o->metadata_chapters_manual = 1;

    return 0;
}

static enum CodecID find_codec_or_die(const char *name, enum AVMediaType type, int encoder)
{
    const char *codec_string = encoder ? "encoder" : "decoder";
    AVCodec *codec;

    if(!name)
        return CODEC_ID_NONE;
    codec = encoder ?
        avcodec_find_encoder_by_name(name) :
        avcodec_find_decoder_by_name(name);
    if(!codec) {
        av_log(NULL, AV_LOG_FATAL, "Unknown %s '%s'\n", codec_string, name);
        exit_program(1);
    }
    if(codec->type != type) {
        av_log(NULL, AV_LOG_FATAL, "Invalid %s type '%s'\n", codec_string, name);
        exit_program(1);
    }
    return codec->id;
}

static AVCodec *choose_codec(OptionsContext *o, AVFormatContext *s, AVStream *st, enum AVMediaType type)
{
    char *codec_name = NULL;

    MATCH_PER_STREAM_OPT(codec_names, str, codec_name, s, st);

    if (!codec_name) {
        if (s->oformat) {
            st->codec->codec_id = av_guess_codec(s->oformat, NULL, s->filename, NULL, type);
            return avcodec_find_encoder(st->codec->codec_id);
        }
    } else if (!strcmp(codec_name, "copy"))
        st->stream_copy = 1;
    else {
        st->codec->codec_id = find_codec_or_die(codec_name, type, s->iformat == NULL);
        return s->oformat ? avcodec_find_encoder_by_name(codec_name) :
                            avcodec_find_decoder_by_name(codec_name);
    }

    return NULL;
}

/**
 * Add all the streams from the given input file to the global
 * list of input streams.
 */
static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
{
    int i, rfps, rfps_base;

    for (i = 0; i < ic->nb_streams; i++) {
        AVStream *st = ic->streams[i];
        AVCodecContext *dec = st->codec;
        InputStream *ist;
        double scale = 1.0;

        input_streams = grow_array(input_streams, sizeof(*input_streams), &nb_input_streams, nb_input_streams + 1);
        ist = &input_streams[nb_input_streams - 1];
        ist->st = st;
        ist->file_index = nb_input_files;
        ist->discard = 1;
        ist->opts = filter_codec_opts(codec_opts, ist->st->codec->codec_id, ic, st);

        MATCH_PER_STREAM_OPT(ts_scale, dbl, scale, ic, st);
        ist->ts_scale = scale;

        ist->dec = choose_codec(o, ic, st, dec->codec_type);
        if (!ist->dec)
            ist->dec = avcodec_find_decoder(dec->codec_id);

        switch (dec->codec_type) {
        case AVMEDIA_TYPE_AUDIO:
            if (o->audio_disable)
                st->discard= AVDISCARD_ALL;
            break;
        case AVMEDIA_TYPE_VIDEO:
            rfps      = ic->streams[i]->r_frame_rate.num;
            rfps_base = ic->streams[i]->r_frame_rate.den;
            if (dec->lowres) {
                dec->flags |= CODEC_FLAG_EMU_EDGE;
                dec->height >>= dec->lowres;
                dec->width  >>= dec->lowres;
            }

            if (dec->time_base.den != rfps*dec->ticks_per_frame || dec->time_base.num != rfps_base) {

                if (verbose >= 0)
                    fprintf(stderr,"\nSeems stream %d codec frame rate differs from container frame rate: %2.2f (%d/%d) -> %2.2f (%d/%d)\n",
                            i, (float)dec->time_base.den / dec->time_base.num, dec->time_base.den, dec->time_base.num,

                    (float)rfps / rfps_base, rfps, rfps_base);
            }

            if (o->video_disable)
                st->discard= AVDISCARD_ALL;
            else if(video_discard)
                st->discard= video_discard;
            break;
        case AVMEDIA_TYPE_DATA:
            break;
        case AVMEDIA_TYPE_SUBTITLE:
            if (o->subtitle_disable)
                st->discard = AVDISCARD_ALL;
            break;
        case AVMEDIA_TYPE_ATTACHMENT:
        case AVMEDIA_TYPE_UNKNOWN:
            break;
        default:
            abort();
        }
    }
}

static int opt_input_file(OptionsContext *o, const char *opt, const char *filename)
{
    AVFormatContext *ic;
    AVInputFormat *file_iformat = NULL;
    int err, i, ret;
    int64_t timestamp;
    uint8_t buf[128];
    AVDictionary **opts;
    int orig_nb_streams;                     // number of streams before avformat_find_stream_info

    if (o->format) {
        if (!(file_iformat = av_find_input_format(o->format))) {
            fprintf(stderr, "Unknown input format: '%s'\n", o->format);
            exit_program(1);
        }
    }

    if (!strcmp(filename, "-"))
        filename = "pipe:";

    using_stdin |= !strncmp(filename, "pipe:", 5) ||
                    !strcmp(filename, "/dev/stdin");

    /* get default parameters from command line */
    ic = avformat_alloc_context();
    if (!ic) {
        print_error(filename, AVERROR(ENOMEM));
        exit_program(1);
    }
    if (o->nb_audio_sample_rate) {
        snprintf(buf, sizeof(buf), "%d", o->audio_sample_rate[o->nb_audio_sample_rate - 1].u.i);
        av_dict_set(&format_opts, "sample_rate", buf, 0);
    }
    if (o->nb_audio_channels) {
        snprintf(buf, sizeof(buf), "%d", o->audio_channels[o->nb_audio_channels - 1].u.i);
        av_dict_set(&format_opts, "channels", buf, 0);
    }
    if (o->nb_frame_rates) {
        av_dict_set(&format_opts, "framerate", o->frame_rates[o->nb_frame_rates - 1].u.str, 0);
    }
    if (o->nb_frame_sizes) {
        av_dict_set(&format_opts, "video_size", o->frame_sizes[o->nb_frame_sizes - 1].u.str, 0);
    }
    if (o->nb_frame_pix_fmts)
        av_dict_set(&format_opts, "pixel_format", o->frame_pix_fmts[o->nb_frame_pix_fmts - 1].u.str, 0);

    ic->flags |= AVFMT_FLAG_NONBLOCK;

    /* open the input file with generic libav function */
    err = avformat_open_input(&ic, filename, file_iformat, &format_opts);
    if (err < 0) {
        print_error(filename, err);
        exit_program(1);
    }
    assert_avoptions(format_opts);

    /* apply forced codec ids */
    for (i = 0; i < ic->nb_streams; i++)
        choose_codec(o, ic, ic->streams[i], ic->streams[i]->codec->codec_type);

    /* Set AVCodecContext options for avformat_find_stream_info */
    opts = setup_find_stream_info_opts(ic, codec_opts);
    orig_nb_streams = ic->nb_streams;

    /* If not enough info to get the stream parameters, we decode the
       first frames to get it. (used in mpeg case for example) */
    ret = avformat_find_stream_info(ic, opts);
    if (ret < 0 && verbose >= 0) {
        fprintf(stderr, "%s: could not find codec parameters\n", filename);
        av_close_input_file(ic);
        exit_program(1);
    }

    timestamp = o->start_time;
    /* add the stream start time */
    if (ic->start_time != AV_NOPTS_VALUE)
        timestamp += ic->start_time;

    /* if seeking requested, we execute it */
    if (o->start_time != 0) {
        ret = av_seek_frame(ic, -1, timestamp, AVSEEK_FLAG_BACKWARD);
        if (ret < 0) {
            fprintf(stderr, "%s: could not seek to position %0.3f\n",
                    filename, (double)timestamp / AV_TIME_BASE);
        }
    }

    /* update the current parameters so that they match the one of the input stream */
    add_input_streams(o, ic);

    /* dump the file content */
    if (verbose >= 0)
        av_dump_format(ic, nb_input_files, filename, 0);

    input_files = grow_array(input_files, sizeof(*input_files), &nb_input_files, nb_input_files + 1);
    input_files[nb_input_files - 1].ctx        = ic;
    input_files[nb_input_files - 1].ist_index  = nb_input_streams - ic->nb_streams;
    input_files[nb_input_files - 1].ts_offset  = o->input_ts_offset - (copy_ts ? 0 : timestamp);
    input_files[nb_input_files - 1].nb_streams = ic->nb_streams;
    input_files[nb_input_files - 1].rate_emu   = o->rate_emu;

    for (i = 0; i < orig_nb_streams; i++)
        av_dict_free(&opts[i]);
    av_freep(&opts);

    reset_options(o);
    return 0;
}

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);
    }
    for (i = 0; i < n; i++) {
        p = i ? strchr(p, ',') + 1 : kf;
        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);
    }
}

static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, enum AVMediaType type)
{
    OutputStream *ost;
    AVStream *st = av_new_stream(oc, oc->nb_streams < o->nb_streamid_map ? o->streamid_map[oc->nb_streams] : 0);
    int idx      = oc->nb_streams - 1;
    int64_t max_frames = INT64_MAX;
    char *bsf = NULL, *next, *codec_tag = NULL;
    AVBitStreamFilterContext *bsfc, *bsfc_prev = NULL;
    double qscale = -1;

    if (!st) {
        av_log(NULL, AV_LOG_FATAL, "Could not alloc stream.\n");
        exit_program(1);
    }

    output_streams = grow_array(output_streams, sizeof(*output_streams), &nb_output_streams,
                                nb_output_streams + 1);
    ost = &output_streams[nb_output_streams - 1];
    ost->file_index = nb_output_files;
    ost->index = idx;
    ost->st    = st;
    st->codec->codec_type = type;
    ost->enc = choose_codec(o, oc, st, type);
    if (ost->enc) {
        ost->opts  = filter_codec_opts(codec_opts, ost->enc->id, oc, st);
    }

    avcodec_get_context_defaults3(st->codec, ost->enc);
    st->codec->codec_type = type; // XXX hack, avcodec_get_context_defaults2() sets type to unknown for stream copy

    MATCH_PER_STREAM_OPT(max_frames, i64, max_frames, oc, st);
    ost->max_frames = max_frames;

    MATCH_PER_STREAM_OPT(bitstream_filters, str, bsf, oc, st);
    while (bsf) {
        if (next = strchr(bsf, ','))
            *next++ = 0;
        if (!(bsfc = av_bitstream_filter_init(bsf))) {
            av_log(NULL, AV_LOG_FATAL, "Unknown bitstream filter %s\n", bsf);
            exit_program(1);
        }
        if (bsfc_prev)
            bsfc_prev->next = bsfc;
        else
            ost->bitstream_filters = bsfc;

        bsfc_prev = bsfc;
        bsf       = next;
    }

    MATCH_PER_STREAM_OPT(codec_tags, str, codec_tag, oc, st);
    if (codec_tag) {
        uint32_t tag = strtol(codec_tag, &next, 0);
        if (*next)
            tag = AV_RL32(codec_tag);
        st->codec->codec_tag = tag;
    }

    MATCH_PER_STREAM_OPT(qscale, dbl, qscale, oc, st);
    if (qscale >= 0 || same_quant) {
        st->codec->flags |= CODEC_FLAG_QSCALE;
        st->codec->global_quality = FF_QP2LAMBDA * qscale;
    }

    ost->sws_flags = av_get_int(sws_opts, "sws_flags", NULL);
    return ost;
}

static void parse_matrix_coeffs(uint16_t *dest, const char *str)
{