1 files changed, 13 insertions, 0 deletions
diff --git a/video/decode/vd_lavc.c b/video/decode/vd_lavc.c
index bae0224e02..923fec308b 100644
--- a/video/decode/vd_lavc.c
+++ b/video/decode/vd_lavc.c
@@ -722,6 +722,19 @@ static int control(struct dec_video *vd, int cmd, void *arg)
     case VDCTRL_RESET:
         reset_avctx(vd);
         return CONTROL_TRUE;
+    case VDCTRL_QUERY_UNSEEN_FRAMES: {
+        AVCodecContext *avctx = ctx->avctx;
+        if (!ctx)
+            break;
+        if (ctx->hwdec && ctx->hwdec->type == HWDEC_RPI)
+            break; // MMAL has arbitrary buffering, thus unknown
+        int delay = avctx->has_b_frames;
+        assert(delay >= 0);
+        if (avctx->active_thread_type & FF_THREAD_FRAME)
+            delay += avctx->thread_count - 1;
+        *(int *)arg = delay;
+        return CONTROL_TRUE;
+    }
     case VDCTRL_GET_HWDEC: {
         int hwdec = ctx->hwdec ? ctx->hwdec->type : 0;
         if (!ctx->software_fallback_decoder)