avconv.c

            *stream_spec = *arg == ':' ? arg + 1 : "";
            break;
        case 'c':
        case 'p':
            if (*(++arg) == ':')
                *index = strtol(++arg, NULL, 0);
            break;
        default:
            av_log(NULL, AV_LOG_FATAL, "Invalid metadata type %c.\n", *arg);
            exit_program(1);
        }
    } else
        *type = 'g';
}

static int copy_metadata(char *outspec, char *inspec, AVFormatContext *oc, AVFormatContext *ic, OptionsContext *o)
{
    AVDictionary **meta_in = NULL;
    AVDictionary **meta_out;
    int i, ret = 0;
    char type_in, type_out;
    const char *istream_spec = NULL, *ostream_spec = NULL;
    int idx_in = 0, idx_out = 0;

    parse_meta_type(inspec,  &type_in,  &idx_in,  &istream_spec);
    parse_meta_type(outspec, &type_out, &idx_out, &ostream_spec);

    if (type_in == 'g' || type_out == 'g')
        o->metadata_global_manual = 1;
    if (type_in == 's' || type_out == 's')
        o->metadata_streams_manual = 1;
    if (type_in == 'c' || type_out == 'c')
        o->metadata_chapters_manual = 1;

#define METADATA_CHECK_INDEX(index, nb_elems, desc)\
    if ((index) < 0 || (index) >= (nb_elems)) {\
        av_log(NULL, AV_LOG_FATAL, "Invalid %s index %d while processing metadata maps.\n",\
                (desc), (index));\
        exit_program(1);\
    }

#define SET_DICT(type, meta, context, index)\
        switch (type) {\
        case 'g':\
            meta = &context->metadata;\
            break;\
        case 'c':\
            METADATA_CHECK_INDEX(index, context->nb_chapters, "chapter")\
            meta = &context->chapters[index]->metadata;\
            break;\
        case 'p':\
            METADATA_CHECK_INDEX(index, context->nb_programs, "program")\
            meta = &context->programs[index]->metadata;\
            break;\
        }\

    SET_DICT(type_in, meta_in, ic, idx_in);
    SET_DICT(type_out, meta_out, oc, idx_out);

    /* for input streams choose first matching stream */
    if (type_in == 's') {
        for (i = 0; i < ic->nb_streams; i++) {
            if ((ret = check_stream_specifier(ic, ic->streams[i], istream_spec)) > 0) {
                meta_in = &ic->streams[i]->metadata;
                break;
            } else if (ret < 0)
                exit_program(1);
        }
        if (!meta_in) {
            av_log(NULL, AV_LOG_FATAL, "Stream specifier %s does not match  any streams.\n", istream_spec);
            exit_program(1);
        }
    }

    if (type_out == 's') {
        for (i = 0; i < oc->nb_streams; i++) {
            if ((ret = check_stream_specifier(oc, oc->streams[i], ostream_spec)) > 0) {
                meta_out = &oc->streams[i]->metadata;
                av_dict_copy(meta_out, *meta_in, AV_DICT_DONT_OVERWRITE);
            } else if (ret < 0)
                exit_program(1);
        }
    } else
        av_dict_copy(meta_out, *meta_in, AV_DICT_DONT_OVERWRITE);

    return 0;
}

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

    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;
}

static AVCodec *choose_decoder(OptionsContext *o, AVFormatContext *s, AVStream *st)
{
    char *codec_name = NULL;

    MATCH_PER_STREAM_OPT(codec_names, str, codec_name, s, st);
    if (codec_name) {
        AVCodec *codec = find_codec_or_die(codec_name, st->codec->codec_type, 0);
        st->codec->codec_id = codec->id;
        return codec;
    } else
        return avcodec_find_decoder(st->codec->codec_id);
}

/**
 * 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;

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

        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;
        st->discard  = AVDISCARD_ALL;
        ist->opts = filter_codec_opts(codec_opts, ist->st->codec->codec_id, ic, st);

        ist->ts_scale = 1.0;
        MATCH_PER_STREAM_OPT(ts_scale, dbl, ist->ts_scale, ic, st);

        ist->dec = choose_decoder(o, ic, st);

        switch (dec->codec_type) {
        case AVMEDIA_TYPE_VIDEO:
            if (dec->lowres) {
                dec->flags |= CODEC_FLAG_EMU_EDGE;
                dec->height >>= dec->lowres;
                dec->width  >>= dec->lowres;
            }

            break;
        case AVMEDIA_TYPE_AUDIO:
        case AVMEDIA_TYPE_DATA:
        case AVMEDIA_TYPE_SUBTITLE:
        case AVMEDIA_TYPE_ATTACHMENT:
        case AVMEDIA_TYPE_UNKNOWN:
            break;
        default:
            abort();
        }
    }
}

static void assert_file_overwrite(const char *filename)
{
    if (!file_overwrite &&
        (strchr(filename, ':') == NULL || filename[1] == ':' ||
         av_strstart(filename, "file:", NULL))) {
        if (avio_check(filename, 0) == 0) {
            if (!using_stdin) {
                fprintf(stderr,"File '%s' already exists. Overwrite ? [y/N] ", filename);
                fflush(stderr);
                if (!read_yesno()) {
                    fprintf(stderr, "Not overwriting - exiting\n");
                    exit_program(1);
                }
            }
            else {
                fprintf(stderr,"File '%s' already exists. Exiting.\n", filename);
                exit_program(1);
            }
        }
    }
}

static void dump_attachment(AVStream *st, const char *filename)
{
    int ret;
    AVIOContext *out = NULL;
    AVDictionaryEntry *e;

    if (!st->codec->extradata_size) {
        av_log(NULL, AV_LOG_WARNING, "No extradata to dump in stream #%d:%d.\n",
               nb_input_files - 1, st->index);
        return;
    }
    if (!*filename && (e = av_dict_get(st->metadata, "filename", NULL, 0)))
        filename = e->value;
    if (!*filename) {
        av_log(NULL, AV_LOG_FATAL, "No filename specified and no 'filename' tag"
               "in stream #%d:%d.\n", nb_input_files - 1, st->index);
        exit_program(1);
    }

    assert_file_overwrite(filename);

    if ((ret = avio_open2(&out, filename, AVIO_FLAG_WRITE, &int_cb, NULL)) < 0) {
        av_log(NULL, AV_LOG_FATAL, "Could not open file %s for writing.\n",
               filename);
        exit_program(1);
    }

    avio_write(out, st->codec->extradata, st->codec->extradata_size);
    avio_flush(out);
    avio_close(out);
}

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))) {
            av_log(NULL, AV_LOG_FATAL, "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;
    ic->interrupt_callback = int_cb;

    /* 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_decoder(o, ic, ic->streams[i]);

    /* 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) {
        av_log(NULL, AV_LOG_FATAL, "%s: could not find codec parameters\n", filename);
        avformat_close_input(&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) {
            av_log(NULL, AV_LOG_WARNING, "%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 */
    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 < o->nb_dump_attachment; i++) {
        int j;

        for (j = 0; j < ic->nb_streams; j++) {
            AVStream *st = ic->streams[j];

            if (check_stream_specifier(ic, st, o->dump_attachment[i].specifier) == 1)
                dump_attachment(st, o->dump_attachment[i].u.str);
        }
    }

    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 uint8_t *get_line(AVIOContext *s)
{
    AVIOContext *line;
    uint8_t *buf;
    char c;

    if (avio_open_dyn_buf(&line) < 0) {
        av_log(NULL, AV_LOG_FATAL, "Could not alloc buffer for reading preset.\n");
        exit_program(1);
    }

    while ((c = avio_r8(s)) && c != '\n')
        avio_w8(line, c);
    avio_w8(line, 0);
    avio_close_dyn_buf(line, &buf);

    return buf;
}

static int get_preset_file_2(const char *preset_name, const char *codec_name, AVIOContext **s)
{
    int i, ret = 1;
    char filename[1000];
    const char *base[3] = { getenv("AVCONV_DATADIR"),
                            getenv("HOME"),
                            AVCONV_DATADIR,
                            };

    for (i = 0; i < FF_ARRAY_ELEMS(base) && ret; i++) {
        if (!base[i])
            continue;
        if (codec_name) {
            snprintf(filename, sizeof(filename), "%s%s/%s-%s.avpreset", base[i],
                     i != 1 ? "" : "/.avconv", codec_name, preset_name);
            ret = avio_open2(s, filename, AVIO_FLAG_READ, &int_cb, NULL);
        }
        if (ret) {
            snprintf(filename, sizeof(filename), "%s%s/%s.avpreset", base[i],
                     i != 1 ? "" : "/.avconv", preset_name);
            ret = avio_open2(s, filename, AVIO_FLAG_READ, &int_cb, NULL);
        }
    }
    return ret;
}

static void choose_encoder(OptionsContext *o, AVFormatContext *s, OutputStream *ost)
{
    char *codec_name = NULL;

    MATCH_PER_STREAM_OPT(codec_names, str, codec_name, s, ost->st);
    if (!codec_name) {
        ost->st->codec->codec_id = av_guess_codec(s->oformat, NULL, s->filename,
                                                  NULL, ost->st->codec->codec_type);
        ost->enc = avcodec_find_encoder(ost->st->codec->codec_id);
    } else if (!strcmp(codec_name, "copy"))
        ost->stream_copy = 1;
    else {
        ost->enc = find_codec_or_die(codec_name, ost->st->codec->codec_type, 1);
        ost->st->codec->codec_id = ost->enc->id;
    }
}

static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, enum AVMediaType type)
{
    OutputStream *ost;
    AVStream *st = avformat_new_stream(oc, NULL);
    int idx      = oc->nb_streams - 1, ret = 0;
    char *bsf = NULL, *next, *codec_tag = NULL;
    AVBitStreamFilterContext *bsfc, *bsfc_prev = NULL;
    double qscale = -1;
    char *buf = NULL, *arg = NULL, *preset = NULL;
    AVIOContext *s = NULL;

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

    if (oc->nb_streams - 1 < o->nb_streamid_map)
        st->id = o->streamid_map[oc->nb_streams - 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;
    choose_encoder(o, oc, ost);
    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(presets, str, preset, oc, st);
    if (preset && (!(ret = get_preset_file_2(preset, ost->enc->name, &s)))) {
        do  {
            buf = get_line(s);
            if (!buf[0] || buf[0] == '#') {
                av_free(buf);
                continue;
            }
            if (!(arg = strchr(buf, '='))) {
                av_log(NULL, AV_LOG_FATAL, "Invalid line found in the preset file.\n");
                exit_program(1);
            }
            *arg++ = 0;
            av_dict_set(&ost->opts, buf, arg, AV_DICT_DONT_OVERWRITE);
            av_free(buf);
        } while (!s->eof_reached);
        avio_close(s);
    }
    if (ret) {
        av_log(NULL, AV_LOG_FATAL,
               "Preset %s specified for stream %d:%d, but could not be opened.\n",
               preset, ost->file_index, ost->index);
        exit_program(1);
    }

    ost->max_frames = INT64_MAX;
    MATCH_PER_STREAM_OPT(max_frames, i64, ost->max_frames, oc, st);

    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;
    }

    if (oc->oformat->flags & AVFMT_GLOBALHEADER)
        st->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;

    av_opt_get_int(sws_opts, "sws_flags", 0, &ost->sws_flags);
    return ost;
}

static void parse_matrix_coeffs(uint16_t *dest, const char *str)
{
    int i;
    const char *p = str;
    for (i = 0;; i++) {
        dest[i] = atoi(p);
        if (i == 63)
            break;
        p = strchr(p, ',');
        if (!p) {
            av_log(NULL, AV_LOG_FATAL, "Syntax error in matrix \"%s\" at coeff %d\n", str, i);
            exit_program(1);
        }
        p++;
    }
}

static OutputStream *new_video_stream(OptionsContext *o, AVFormatContext *oc)
{
    AVStream *st;
    OutputStream *ost;
    AVCodecContext *video_enc;

    ost = new_output_stream(o, oc, AVMEDIA_TYPE_VIDEO);
    st  = ost->st;
    video_enc = st->codec;

    if (!ost->stream_copy) {
        const char *p = NULL;
        char *forced_key_frames = NULL, *frame_rate = NULL, *frame_size = NULL;
        char *frame_aspect_ratio = NULL, *frame_pix_fmt = NULL;
        char *intra_matrix = NULL, *inter_matrix = NULL, *filters = NULL;
        int i;

        MATCH_PER_STREAM_OPT(frame_rates, str, frame_rate, oc, st);
        if (frame_rate && av_parse_video_rate(&ost->frame_rate, frame_rate) < 0) {
            av_log(NULL, AV_LOG_FATAL, "Invalid framerate value: %s\n", frame_rate);
            exit_program(1);
        }

        MATCH_PER_STREAM_OPT(frame_sizes, str, frame_size, oc, st);
        if (frame_size && av_parse_video_size(&video_enc->width, &video_enc->height, frame_size) < 0) {
            av_log(NULL, AV_LOG_FATAL, "Invalid frame size: %s.\n", frame_size);
            exit_program(1);
        }

        MATCH_PER_STREAM_OPT(frame_aspect_ratios, str, frame_aspect_ratio, oc, st);
        if (frame_aspect_ratio)
            ost->frame_aspect_ratio = parse_frame_aspect_ratio(frame_aspect_ratio);

        MATCH_PER_STREAM_OPT(frame_pix_fmts, str, frame_pix_fmt, oc, st);
        if (frame_pix_fmt && (video_enc->pix_fmt = av_get_pix_fmt(frame_pix_fmt)) == PIX_FMT_NONE) {
            av_log(NULL, AV_LOG_FATAL, "Unknown pixel format requested: %s.\n", frame_pix_fmt);
            exit_program(1);
        }
        st->sample_aspect_ratio = video_enc->sample_aspect_ratio;

        MATCH_PER_STREAM_OPT(intra_matrices, str, intra_matrix, oc, st);
        if (intra_matrix) {
            if (!(video_enc->intra_matrix = av_mallocz(sizeof(*video_enc->intra_matrix) * 64))) {
                av_log(NULL, AV_LOG_FATAL, "Could not allocate memory for intra matrix.\n");
                exit_program(1);
            }
            parse_matrix_coeffs(video_enc->intra_matrix, intra_matrix);
        }
        MATCH_PER_STREAM_OPT(inter_matrices, str, inter_matrix, oc, st);
        if (inter_matrix) {
            if (!(video_enc->inter_matrix = av_mallocz(sizeof(*video_enc->inter_matrix) * 64))) {
                av_log(NULL, AV_LOG_FATAL, "Could not allocate memory for inter matrix.\n");
                exit_program(1);
            }
            parse_matrix_coeffs(video_enc->inter_matrix, inter_matrix);
        }

        MATCH_PER_STREAM_OPT(rc_overrides, str, p, oc, st);
        for (i = 0; p; i++) {
            int start, end, q;
            int e = sscanf(p, "%d,%d,%d", &start, &end, &q);
            if (e != 3) {
                av_log(NULL, AV_LOG_FATAL, "error parsing rc_override\n");
                exit_program(1);
            }
            video_enc->rc_override =
                av_realloc(video_enc->rc_override,
                           sizeof(RcOverride) * (i + 1));
            video_enc->rc_override[i].start_frame = start;
            video_enc->rc_override[i].end_frame   = end;
            if (q > 0) {
                video_enc->rc_override[i].qscale         = q;
                video_enc->rc_override[i].quality_factor = 1.0;
            }
            else {
                video_enc->rc_override[i].qscale         = 0;
                video_enc->rc_override[i].quality_factor = -q/100.0;
            }
            p = strchr(p, '/');
            if (p) p++;
        }
        video_enc->rc_override_count = i;
        if (!video_enc->rc_initial_buffer_occupancy)
            video_enc->rc_initial_buffer_occupancy = video_enc->rc_buffer_size * 3 / 4;
        video_enc->intra_dc_precision = intra_dc_precision - 8;

        /* two pass mode */
        if (do_pass) {
            if (do_pass == 1) {
                video_enc->flags |= CODEC_FLAG_PASS1;
            } else {
                video_enc->flags |= CODEC_FLAG_PASS2;
            }
        }

        MATCH_PER_STREAM_OPT(forced_key_frames, str, forced_key_frames, oc, st);
        if (forced_key_frames)
            parse_forced_key_frames(forced_key_frames, ost, video_enc);

        MATCH_PER_STREAM_OPT(force_fps, i, ost->force_fps, oc, st);

        ost->top_field_first = -1;
        MATCH_PER_STREAM_OPT(top_field_first, i, ost->top_field_first, oc, st);

        MATCH_PER_STREAM_OPT(filters, str, filters, oc, st);
        if (filters)
            ost->avfilter = av_strdup(filters);
    } else {
        MATCH_PER_STREAM_OPT(copy_initial_nonkeyframes, i, ost->copy_initial_nonkeyframes, oc ,st);
    }

    return ost;
}

static OutputStream *new_audio_stream(OptionsContext *o, AVFormatContext *oc)
{
    AVStream *st;
    OutputStream *ost;
    AVCodecContext *audio_enc;

    ost = new_output_stream(o, oc, AVMEDIA_TYPE_AUDIO);
    st  = ost->st;

    audio_enc = st->codec;
    audio_enc->codec_type = AVMEDIA_TYPE_AUDIO;

    if (!ost->stream_copy) {
        char *sample_fmt = NULL;

        MATCH_PER_STREAM_OPT(audio_channels, i, audio_enc->channels, oc, st);

        MATCH_PER_STREAM_OPT(sample_fmts, str, sample_fmt, oc, st);
        if (sample_fmt &&
            (audio_enc->sample_fmt = av_get_sample_fmt(sample_fmt)) == AV_SAMPLE_FMT_NONE) {
            av_log(NULL, AV_LOG_FATAL, "Invalid sample format '%s'\n", sample_fmt);
            exit_program(1);
        }

        MATCH_PER_STREAM_OPT(audio_sample_rate, i, audio_enc->sample_rate, oc, st);
    }

    return ost;
}

static OutputStream *new_data_stream(OptionsContext *o, AVFormatContext *oc)
{
    OutputStream *ost;

    ost = new_output_stream(o, oc, AVMEDIA_TYPE_DATA);
    if (!ost->stream_copy) {
        av_log(NULL, AV_LOG_FATAL, "Data stream encoding not supported yet (only streamcopy)\n");
        exit_program(1);
    }

    return ost;
}

static OutputStream *new_attachment_stream(OptionsContext *o, AVFormatContext *oc)
{
    OutputStream *ost = new_output_stream(o, oc, AVMEDIA_TYPE_ATTACHMENT);
    ost->stream_copy = 1;
    return ost;
}

static OutputStream *new_subtitle_stream(OptionsContext *o, AVFormatContext *oc)
{
    AVStream *st;
    OutputStream *ost;
    AVCodecContext *subtitle_enc;

    ost = new_output_stream(o, oc, AVMEDIA_TYPE_SUBTITLE);
    st  = ost->st;
    subtitle_enc = st->codec;

    subtitle_enc->codec_type = AVMEDIA_TYPE_SUBTITLE;

    return ost;
}

/* arg format is "output-stream-index:streamid-value". */
static int opt_streamid(OptionsContext *o, const char *opt, const char *arg)
{
    int idx;
    char *p;
    char idx_str[16];

    av_strlcpy(idx_str, arg, sizeof(idx_str));
    p = strchr(idx_str, ':');
    if (!p) {
        av_log(NULL, AV_LOG_FATAL,
               "Invalid value '%s' for option '%s', required syntax is 'index:value'\n",
               arg, opt);
        exit_program(1);
    }
    *p++ = '\0';
    idx = parse_number_or_die(opt, idx_str, OPT_INT, 0, INT_MAX);
    o->streamid_map = grow_array(o->streamid_map, sizeof(*o->streamid_map), &o->nb_streamid_map, idx+1);
    o->streamid_map[idx] = parse_number_or_die(opt, p, OPT_INT, 0, INT_MAX);
    return 0;
}

static int copy_chapters(InputFile *ifile, OutputFile *ofile, int copy_metadata)
{
    AVFormatContext *is = ifile->ctx;
    AVFormatContext *os = ofile->ctx;
    int i;

    for (i = 0; i < is->nb_chapters; i++) {
        AVChapter *in_ch = is->chapters[i], *out_ch;
        int64_t ts_off   = av_rescale_q(ofile->start_time - ifile->ts_offset,
                                       AV_TIME_BASE_Q, in_ch->time_base);
        int64_t rt       = (ofile->recording_time == INT64_MAX) ? INT64_MAX :
                           av_rescale_q(ofile->recording_time, AV_TIME_BASE_Q, in_ch->time_base);


        if (in_ch->end < ts_off)
            continue;
        if (rt != INT64_MAX && in_ch->start > rt + ts_off)
            break;

        out_ch = av_mallocz(sizeof(AVChapter));
        if (!out_ch)
            return AVERROR(ENOMEM);

        out_ch->id        = in_ch->id;
        out_ch->time_base = in_ch->time_base;
        out_ch->start     = FFMAX(0,  in_ch->start - ts_off);
        out_ch->end       = FFMIN(rt, in_ch->end   - ts_off);

        if (copy_metadata)
            av_dict_copy(&out_ch->metadata, in_ch->metadata, 0);

        os->nb_chapters++;
        os->chapters = av_realloc(os->chapters, sizeof(AVChapter) * os->nb_chapters);
        if (!os->chapters)
            return AVERROR(ENOMEM);
        os->chapters[os->nb_chapters - 1] = out_ch;
    }
    return 0;
}

static void opt_output_file(void *optctx, const char *filename)
{
    OptionsContext *o = optctx;
    AVFormatContext *oc;
    int i, err;
    AVOutputFormat *file_oformat;
    OutputStream *ost;
    InputStream  *ist;

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

    oc = avformat_alloc_context();
    if (!oc) {
        print_error(filename, AVERROR(ENOMEM));
        exit_program(1);
    }

    if (o->format) {
        file_oformat = av_guess_format(o->format, NULL, NULL);
        if (!file_oformat) {
            av_log(NULL, AV_LOG_FATAL, "Requested output format '%s' is not a suitable output format\n", o->format);
            exit_program(1);
        }
    } else {
        file_oformat = av_guess_format(NULL, filename, NULL);
        if (!file_oformat) {
            av_log(NULL, AV_LOG_FATAL, "Unable to find a suitable output format for '%s'\n",
                   filename);
            exit_program(1);
        }
    }

    oc->oformat = file_oformat;
    oc->interrupt_callback = int_cb;
    av_strlcpy(oc->filename, filename, sizeof(oc->filename));

    if (!o->nb_stream_maps) {
        /* pick the "best" stream of each type */
#define NEW_STREAM(type, index)\
        if (index >= 0) {\
            ost = new_ ## type ## _stream(o, oc);\
            ost->source_index = index;\
            ost->sync_ist     = &input_streams[index];\
            input_streams[index].discard = 0;\
            input_streams[index].st->discard = AVDISCARD_NONE;\
        }

        /* video: highest resolution */
        if (!o->video_disable && oc->oformat->video_codec != CODEC_ID_NONE) {
            int area = 0, idx = -1;
            for (i = 0; i < nb_input_streams; i++) {
                ist = &input_streams[i];
                if (ist->st->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
                    ist->st->codec->width * ist->st->codec->height > area) {
                    area = ist->st->codec->width * ist->st->codec->height;
                    idx = i;
                }
            }
            NEW_STREAM(video, idx);
        }

        /* audio: most channels */
        if (!o->audio_disable && oc->oformat->audio_codec != CODEC_ID_NONE) {
            int channels = 0, idx = -1;
            for (i = 0; i < nb_input_streams; i++) {
                ist = &input_streams[i];
                if (ist->st->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
                    ist->st->codec->channels > channels) {
                    channels = ist->st->codec->channels;
                    idx = i;
                }
            }
            NEW_STREAM(audio, idx);
        }

        /* subtitles: pick first */
        if (!o->subtitle_disable && oc->oformat->subtitle_codec != CODEC_ID_NONE) {
            for (i = 0; i < nb_input_streams; i++)
                if (input_streams[i].st->codec->codec_type == AVMEDIA_TYPE_SUBTITLE) {
                    NEW_STREAM(subtitle, i);
                    break;
                }
        }
        /* do something with data? */
    } else {
        for (i = 0; i < o->nb_stream_maps; i++) {
            StreamMap *map = &o->stream_maps[i];

            if (map->disabled)
                continue;

            ist = &input_streams[input_files[map->file_index].ist_index + map->stream_index];
            switch (ist->st->codec->codec_type) {
            case AVMEDIA_TYPE_VIDEO:    ost = new_video_stream(o, oc);    break;
            case AVMEDIA_TYPE_AUDIO:    ost = new_audio_stream(o, oc);    break;
            case AVMEDIA_TYPE_SUBTITLE: ost = new_subtitle_stream(o, oc); break;
            case AVMEDIA_TYPE_DATA:     ost = new_data_stream(o, oc);     break;
            case AVMEDIA_TYPE_ATTACHMENT: ost = new_attachment_stream(o, oc); break;
            default:
                av_log(NULL, AV_LOG_FATAL, "Cannot map stream #%d:%d - unsupported type.\n",
                       map->file_index, map->stream_index);
                exit_program(1);
            }

            ost->source_index = input_files[map->file_index].ist_index + map->stream_index;
            ost->sync_ist     = &input_streams[input_files[map->sync_file_index].ist_index +
                                           map->sync_stream_index];
            ist->discard = 0;
            ist->st->discard = AVDISCARD_NONE;
        }
    }

    /* handle attached files */
    for (i = 0; i < o->nb_attachments; i++) {
        AVIOContext *pb;
        uint8_t *attachment;
        const char *p;
        int64_t len;

        if ((err = avio_open2(&pb, o->attachments[i], AVIO_FLAG_READ, &int_cb, NULL)) < 0) {
            av_log(NULL, AV_LOG_FATAL, "Could not open attachment file %s.\n",
                   o->attachments[i]);
            exit_program(1);
        }
        if ((len = avio_size(pb)) <= 0) {
            av_log(NULL, AV_LOG_FATAL, "Could not get size of the attachment %s.\n",
                   o->attachments[i]);
            exit_program(1);
        }
        if (!(attachment = av_malloc(len))) {
            av_log(NULL, AV_LOG_FATAL, "Attachment %s too large to fit into memory.\n",
                   o->attachments[i]);
            exit_program(1);
        }
        avio_read(pb, attachment, len);

        ost = new_attachment_stream(o, oc);
        ost->stream_copy               = 0;
        ost->source_index              = -1;
        ost->attachment_filename       = o->attachments[i];
        ost->st->codec->extradata      = attachment;
        ost->st->codec->extradata_size = len;

        p = strrchr(o->attachments[i], '/');
        av_dict_set(&ost->st->metadata, "filename", (p && *p) ? p + 1 : o->attachments[i], AV_DICT_DONT_OVERWRITE);
        avio_close(pb);
    }

    output_files = grow_array(output_files, sizeof(*output_files), &nb_output_files, nb_output_files + 1);
    output_files[nb_output_files - 1].ctx       = oc;
    output_files[nb_output_files - 1].ost_index = nb_output_streams - oc->nb_streams;
    output_files[nb_output_files - 1].recording_time = o->recording_time;
    if (o->recording_time != INT64_MAX)
        oc->duration = o->recording_time;
    output_files[nb_output_files - 1].start_time     = o->start_time;
    output_files[nb_output_files - 1].limit_filesize = o->limit_filesize;
    av_dict_copy(&output_files[nb_output_files - 1].opts, format_opts, 0);

    /* check filename in case of an image number is expected */
    if (oc->oformat->flags & AVFMT_NEEDNUMBER) {
        if (!av_filename_number_test(oc->filename)) {
            print_error(oc->filename, AVERROR(EINVAL));
            exit_program(1);
        }
    }

    if (!(oc->oformat->flags & AVFMT_NOFILE)) {
        /* test if it already exists to avoid losing precious files */
        assert_file_overwrite(filename);

        /* open the file */
        if ((err = avio_open2(&oc->pb, filename, AVIO_FLAG_WRITE,
                              &oc->interrupt_callback,
                              &output_files[nb_output_files - 1].opts)) < 0) {
            print_error(filename, err);
            exit_program(1);
        }
    }

    if (o->mux_preload) {
        uint8_t buf[64];
        snprintf(buf, sizeof(buf), "%d", (int)(o->mux_preload*AV_TIME_BASE));
        av_dict_set(&output_files[nb_output_files - 1].opts, "preload", buf, 0);
    }
    oc->max_delay = (int)(o->mux_max_delay * AV_TIME_BASE);
    oc->flags |= AVFMT_FLAG_NONBLOCK;

    /* copy metadata */
    for (i = 0; i < o->nb_metadata_map; i++) {
        char *p;
        int in_file_index = strtol(o->metadata_map[i].u.str, &p, 0);

        if (in_file_index < 0)
            continue;
        if (in_file_index >= nb_input_files) {
            av_log(NULL, AV_LOG_FATAL, "Invalid input file index %d while processing metadata maps\n", in_file_index);
            exit_program(1);
        }
        copy_metadata(o->metadata_map[i].specifier, *p ? p + 1 : p, oc, input_files[in_file_index].ctx, o);
    }

    /* copy chapters */
    if (o->chapters_input_file >= nb_input_files) {
        if (o->chapters_input_file == INT_MAX) {
            /* copy chapters from the first input file that has them*/
            o->chapters_input_file = -1;
            for (i = 0; i < nb_input_files; i++)
                if (input_files[i].ctx->nb_chapters) {
                    o->chapters_input_file = i;
                    break;
                }
        } else {
            av_log(NULL, AV_LOG_FATAL, "Invalid input file index %d in chapter mapping.\n",
                   o->chapters_input_file);
            exit_program(1);