vaapioverlay: ensure sinkpad has current buffer

Use the gst_video_aggregator_pad_has_current_buffer API
to check if the current sinkpad has a queued buffer before
attempting to obtain a input buffer from the base plugin.
If the sinkpad does not have a current buffer, then it is
either not producing them yet (e.g. current time < sinkpad
start time) or it has reached EOS.

Previously, we only handled EOS case.

Example:

 gst-launch-1.0 videotestsrc num-buffers=100 \
  ! vaapipostproc ! vaapioverlay name=overlay \
  ! vaapisink videotestsrc timestamp-offset=1000000000 \
  num-buffers=100 ! video/x-raw,width=160,height=120 \
  ! overlay.

diff --git a/gst/vaapi/gstvaapioverlay.c b/gst/vaapi/gstvaapioverlay.c
index 7cdb21e..53efdac 100644 (file)
--- a/gst/vaapi/gstvaapioverlay.c
+++ b/gst/vaapi/gstvaapioverlay.c
@@ -385,6 +385,11 @@ gst_vaapi_overlay_surface_next (gpointer data)
     blend_surface = &generator->blend_surface;
     blend_surface->surface = NULL;
 
+    /* Current sinkpad may not be queueing buffers yet (e.g. timestamp-offset)
+     * or it may have reached EOS */
+    if (!gst_video_aggregator_pad_has_current_buffer (vagg_pad))
+      continue;
+
     inframe = gst_video_aggregator_pad_get_prepared_frame (vagg_pad);
     buf = gst_video_aggregator_pad_get_current_buffer (vagg_pad);
     pad = GST_VAAPI_OVERLAY_SINK_PAD (vagg_pad);
@@ -393,10 +398,6 @@ gst_vaapi_overlay_surface_next (gpointer data)
             (generator->overlay), GST_PAD (pad), buf, &inbuf) != GST_FLOW_OK)
       return blend_surface;
 
-    /* Current sinkpad may have reached EOS */
-    if (!inframe || !inbuf)
-      continue;
-
     inbuf_meta = gst_buffer_get_vaapi_video_meta (inbuf);
     if (inbuf_meta) {
       blend_surface->surface = gst_vaapi_video_meta_get_surface (inbuf_meta);