decoder: vp9: Update comment about context resets

Clarify that vaapi context resets are never needed for vp9, but
that ensure_context() needs called when the size increases so that
new surfaces can be allocated.

Signed-off-by: Scott D Phillips <scott.d.phillips@intel.com>
https://bugzilla.gnome.org/show_bug.cgi?id=767474

diff --git a/gst-libs/gst/vaapi/gstvaapidecoder_vp9.c b/gst-libs/gst/vaapi/gstvaapidecoder_vp9.c
index 74f92d8..0443488 100644 (file)
--- a/gst-libs/gst/vaapi/gstvaapidecoder_vp9.c
+++ b/gst-libs/gst/vaapi/gstvaapidecoder_vp9.c
@@ -600,9 +600,10 @@ parse_frame_header (GstVaapiDecoderVp9 * decoder, const guchar * buf,
     return get_status (result);
 
   /* Unlike other decoders, vp9 decoder doesn't need to reset the
-   * whole context and surfaces for each resolution change. context
-   * reset only needed if resolution of any frame is greater than
-   * what actullay configured. There are streams where a bigger
+   * whole context and surfaces for each resolution change. Calling
+   * ensure_context() again is only needed if the resolution of any frame
+   * is greater than what was previously configured, so that new, larger
+   * surfaces can be allocated. There are streams where a bigger
    * resolution set in ivf header or webm header but actual resolution
    * of all frames are less. Also it is possible to have inter-prediction
    * between these multi resolution frames */