Function ff_thread_receive_frame

libavcodec/pthread_frame.c:563–627

}

int ff_thread_receive_frame(AVCodecContext *avctx, AVFrame *frame, unsigned flags)
{
    FrameThreadContext *fctx = avctx->internal->thread_ctx;
    int ret = 0;

    /* release the async lock, permitting blocked hwaccel threads to
     * go forward while we are in this function */
    async_unlock(fctx);

    /* submit packets to threads while there are no buffered results to return */
    while (!fctx->df.nb_f && !fctx->result) {
        PerThreadContext *p;

        if (fctx->next_decoding != fctx->next_finished &&
            (flags & AV_CODEC_RECEIVE_FRAME_FLAG_SYNCHRONOUS))
            goto wait_for_result;

        /* get a packet to be submitted to the next thread */
        av_packet_unref(fctx->next_pkt);
        ret = ff_decode_get_packet(avctx, fctx->next_pkt);
        if (ret < 0 && ret != AVERROR_EOF)
            goto finish;

        ret = submit_packet(&fctx->threads[fctx->next_decoding], avctx,
                            fctx->next_pkt);
        if (ret < 0)
             goto finish;

        /* do not return any frames until all threads have something to do */
        if (fctx->next_decoding != fctx->next_finished &&
            !avctx->internal->draining)
            continue;

    wait_for_result:
        p                   = &fctx->threads[fctx->next_finished];
        fctx->next_finished = (fctx->next_finished + 1) % avctx->thread_count;

        if (atomic_load(&p->state) != STATE_INPUT_READY) {
            pthread_mutex_lock(&p->progress_mutex);
            while (atomic_load_explicit(&p->state, memory_order_relaxed) != STATE_INPUT_READY)
                pthread_cond_wait(&p->output_cond, &p->progress_mutex);
            pthread_mutex_unlock(&p->progress_mutex);
        }

        update_context_from_thread(avctx, p->avctx, 1);
        fctx->result = p->result;
        p->result    = 0;
        if (p->df.nb_f)
            FFSWAP(DecodedFrames, fctx->df, p->df);
    }

    /* a thread may return multiple frames AND an error
     * we first return all the frames, then the error */
    if (fctx->df.nb_f) {
        decoded_frames_pop(&fctx->df, frame);
        ret = 0;
    } else {
        ret = fctx->result;