cmdutils.c

                if (s->streams[i]->codec->codec_type == type && index-- == 0)
                   return i == st->index;
            return 0;
        }
        return 1;
    } else if (*spec == 'p' && *(spec + 1) == ':') {
        int prog_id, i, j;
        char *endptr;
        spec += 2;
        prog_id = strtol(spec, &endptr, 0);
        for (i = 0; i < s->nb_programs; i++) {
            if (s->programs[i]->id != prog_id)
                continue;

            if (*endptr++ == ':') {
                int stream_idx = strtol(endptr, NULL, 0);
                return (stream_idx >= 0 && stream_idx < s->programs[i]->nb_stream_indexes &&
                        st->index == s->programs[i]->stream_index[stream_idx]);
            }

            for (j = 0; j < s->programs[i]->nb_stream_indexes; j++)
                if (st->index == s->programs[i]->stream_index[j])
                    return 1;
        }
        return 0;
    } else if (!*spec) /* empty specifier, matches everything */
        return 1;

    av_log(s, AV_LOG_ERROR, "Invalid stream specifier: %s.\n", spec);
    return AVERROR(EINVAL);
}

AVDictionary *filter_codec_opts(AVDictionary *opts, AVCodec *codec, AVFormatContext *s, AVStream *st)
{
    AVDictionary    *ret = NULL;
    AVDictionaryEntry *t = NULL;
    int            flags = s->oformat ? AV_OPT_FLAG_ENCODING_PARAM : AV_OPT_FLAG_DECODING_PARAM;
    char          prefix = 0;
    const AVClass    *cc = avcodec_get_class();

    if (!codec)
        return NULL;

    switch (codec->type) {
    case AVMEDIA_TYPE_VIDEO:    prefix = 'v'; flags |= AV_OPT_FLAG_VIDEO_PARAM;    break;
    case AVMEDIA_TYPE_AUDIO:    prefix = 'a'; flags |= AV_OPT_FLAG_AUDIO_PARAM;    break;
    case AVMEDIA_TYPE_SUBTITLE: prefix = 's'; flags |= AV_OPT_FLAG_SUBTITLE_PARAM; break;
    }

    while (t = av_dict_get(opts, "", t, AV_DICT_IGNORE_SUFFIX)) {
        char *p = strchr(t->key, ':');

        /* check stream specification in opt name */
        if (p)
            switch (check_stream_specifier(s, st, p + 1)) {
            case  1: *p = 0; break;
            case  0:         continue;
            default:         return NULL;
            }

        if (av_opt_find(&cc, t->key, NULL, flags, AV_OPT_SEARCH_FAKE_OBJ) ||
            (codec && codec->priv_class && av_opt_find(&codec->priv_class, t->key, NULL, flags, AV_OPT_SEARCH_FAKE_OBJ)))
            av_dict_set(&ret, t->key, t->value, 0);
        else if (t->key[0] == prefix && av_opt_find(&cc, t->key+1, NULL, flags, AV_OPT_SEARCH_FAKE_OBJ))
            av_dict_set(&ret, t->key+1, t->value, 0);

        if (p)
            *p = ':';
    }
    return ret;
}

AVDictionary **setup_find_stream_info_opts(AVFormatContext *s, AVDictionary *codec_opts)
{
    int i;
    AVDictionary **opts;

    if (!s->nb_streams)
        return NULL;
    opts = av_mallocz(s->nb_streams * sizeof(*opts));
    if (!opts) {
        av_log(NULL, AV_LOG_ERROR, "Could not alloc memory for stream options.\n");
        return NULL;
    }
    for (i = 0; i < s->nb_streams; i++)
        opts[i] = filter_codec_opts(codec_opts, avcodec_find_decoder(s->streams[i]->codec->codec_id), s, s->streams[i]);
    return opts;
}

void *grow_array(void *array, int elem_size, int *size, int new_size)
{
    if (new_size >= INT_MAX / elem_size) {
        av_log(NULL, AV_LOG_ERROR, "Array too big.\n");
        exit_program(1);
    }
    if (*size < new_size) {
        uint8_t *tmp = av_realloc(array, new_size*elem_size);
        if (!tmp) {
            av_log(NULL, AV_LOG_ERROR, "Could not alloc buffer.\n");
            exit_program(1);
        }
        memset(tmp + *size*elem_size, 0, (new_size-*size) * elem_size);
        *size = new_size;
        return tmp;
    }
    return array;
}