Function decode

ffmpeg-single-cmd/src/main/cpp/ffmpeg_mod.c:2257–2278

This does not quite work like avcodec_decode_audio4/avcodec_decode_video2. There is the following difference: if you got a frame, you must call it again with pkt=NULL. pkt==NULL is treated differently from pkt.size==0 (pkt==NULL means get more output, pkt.size==0 is a flush/drain packet)

// it again with pkt=NULL. pkt==NULL is treated differently from pkt.size==0
// (pkt==NULL means get more output, pkt.size==0 is a flush/drain packet)
static int decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
{
    int ret;

    *got_frame = 0;

    if (pkt) {
        ret = avcodec_send_packet(avctx, pkt);
        // In particular, we don't expect AVERROR(EAGAIN), because we read all
        // decoded frames with avcodec_receive_frame() until done.
        if (ret < 0 && ret != AVERROR_EOF)
            return ret;
    }

    ret = avcodec_receive_frame(avctx, frame);
    if (ret < 0 && ret != AVERROR(EAGAIN))
        return ret;
    if (ret >= 0)
        *got_frame = 1;

    return 0;
}

static int send_frame_to_filters(InputStream *ist, AVFrame *decoded_frame)
{