Function try_decode_frame

libavformat/demux.c:2138–2238

returns 1 or 0 if or if not decoded data was returned, or a negative error */

/* returns 1 or 0 if or if not decoded data was returned, or a negative error */
static int try_decode_frame(AVFormatContext *s, AVStream *st,
                            const AVPacket *pkt, AVDictionary **options)
{
    FFStream *const sti = ffstream(st);
    AVCodecContext *const avctx = sti->avctx;
    const AVCodec *codec;
    int got_picture = 1, ret = 0;
    AVFrame *frame = av_frame_alloc();
    AVSubtitle subtitle;
    int do_skip_frame = 0;
    enum AVDiscard skip_frame;
    int pkt_to_send = pkt->size > 0;

    if (!frame)
        return AVERROR(ENOMEM);

    if (!avcodec_is_open(avctx) &&
        sti->info->found_decoder <= 0 &&
        (st->codecpar->codec_id != -sti->info->found_decoder || !st->codecpar->codec_id)) {
        AVDictionary *thread_opt = NULL;

        codec = find_probe_decoder(s, st, st->codecpar->codec_id);

        if (!codec) {
            sti->info->found_decoder = -st->codecpar->codec_id;
            ret                     = -1;
            goto fail;
        }

        /* Force thread count to 1 since the H.264 decoder will not extract
         * SPS and PPS to extradata during multi-threaded decoding. */
        av_dict_set(options ? options : &thread_opt, "threads", "1", 0);
        /* Force lowres to 0. The decoder might reduce the video size by the
         * lowres factor, and we don't want that propagated to the stream's
         * codecpar */
        av_dict_set(options ? options : &thread_opt, "lowres", "0", 0);
        if (s->codec_whitelist)
            av_dict_set(options ? options : &thread_opt, "codec_whitelist", s->codec_whitelist, 0);
        ret = avcodec_open2(avctx, codec, options ? options : &thread_opt);
        if (!options)
            av_dict_free(&thread_opt);
        if (ret < 0) {
            sti->info->found_decoder = -avctx->codec_id;
            goto fail;
        }
        sti->info->found_decoder = 1;
    } else if (!sti->info->found_decoder)
        sti->info->found_decoder = 1;

    if (sti->info->found_decoder < 0) {
        ret = -1;
        goto fail;
    }

    if (avpriv_codec_get_cap_skip_frame_fill_param(avctx->codec)) {
        do_skip_frame = 1;
        skip_frame = avctx->skip_frame;
        avctx->skip_frame = AVDISCARD_ALL;