+static void frame_queue_unref_item(Frame *vp)
+{
+ av_frame_unref(vp->frame);
+ avsubtitle_free(&vp->sub);
+}
+
+static int frame_queue_init(FrameQueue *f, PacketQueue *pktq, int max_size, int keep_last)
+{
+ int i;
+ memset(f, 0, sizeof(FrameQueue));
+ if (!(f->mutex = SDL_CreateMutex()))
+ return AVERROR(ENOMEM);
+ if (!(f->cond = SDL_CreateCond()))
+ return AVERROR(ENOMEM);
+ f->pktq = pktq;
+ f->max_size = FFMIN(max_size, FRAME_QUEUE_SIZE);
+ f->keep_last = !!keep_last;
+ for (i = 0; i < f->max_size; i++)
+ if (!(f->queue[i].frame = av_frame_alloc()))
+ return AVERROR(ENOMEM);
+ return 0;
+}
+
+static void frame_queue_destory(FrameQueue *f)
+{
+ int i;
+ for (i = 0; i < f->max_size; i++) {
+ Frame *vp = &f->queue[i];
+ frame_queue_unref_item(vp);
+ av_frame_free(&vp->frame);
+ free_picture(vp);
+ }
+ SDL_DestroyMutex(f->mutex);
+ SDL_DestroyCond(f->cond);
+}
+
+static void frame_queue_signal(FrameQueue *f)
+{
+ SDL_LockMutex(f->mutex);
+ SDL_CondSignal(f->cond);
+ SDL_UnlockMutex(f->mutex);
+}
+
+static Frame *frame_queue_peek(FrameQueue *f)
+{
+ return &f->queue[(f->rindex + f->rindex_shown) % f->max_size];
+}
+
+static Frame *frame_queue_peek_next(FrameQueue *f)
+{
+ return &f->queue[(f->rindex + f->rindex_shown + 1) % f->max_size];
+}
+
+static Frame *frame_queue_peek_last(FrameQueue *f)
+{
+ return &f->queue[f->rindex];
+}
+
+static Frame *frame_queue_peek_writable(FrameQueue *f)
+{
+ /* wait until we have space to put a new frame */
+ SDL_LockMutex(f->mutex);
+ while (f->size >= f->max_size &&
+ !f->pktq->abort_request) {
+ SDL_CondWait(f->cond, f->mutex);
+ }
+ SDL_UnlockMutex(f->mutex);
+
+ if (f->pktq->abort_request)
+ return NULL;
+
+ return &f->queue[f->windex];
+}
+
+static void frame_queue_push(FrameQueue *f)
+{
+ if (++f->windex == f->max_size)
+ f->windex = 0;
+ SDL_LockMutex(f->mutex);
+ f->size++;
+ SDL_UnlockMutex(f->mutex);
+}
+
+static void frame_queue_next(FrameQueue *f)
+{
+ if (f->keep_last && !f->rindex_shown) {
+ f->rindex_shown = 1;
+ return;
+ }
+ frame_queue_unref_item(&f->queue[f->rindex]);
+ if (++f->rindex == f->max_size)
+ f->rindex = 0;
+ SDL_LockMutex(f->mutex);
+ f->size--;
+ SDL_CondSignal(f->cond);
+ SDL_UnlockMutex(f->mutex);
+}
+
+/* jump back to the previous frame if available by resetting rindex_shown */
+static int frame_queue_prev(FrameQueue *f)
+{
+ int ret = f->rindex_shown;
+ f->rindex_shown = 0;
+ return ret;
+}
+
+/* return the number of undisplayed frames in the queue */
+static int frame_queue_nb_remaining(FrameQueue *f)
+{
+ return f->size - f->rindex_shown;
+}
+
+/* return last shown position */
+static int64_t frame_queue_last_pos(FrameQueue *f)
+{
+ Frame *fp = &f->queue[f->rindex];
+ if (f->rindex_shown && fp->serial == f->pktq->serial)
+ return fp->pos;
+ else
+ return -1;
+}
+