avcodec: Constify ThreadFrames if possible

This is possible now that ff_thread_await_progress() accepts
a const ThreadFrame*.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
index 53fc514788..3f6b0100d9 100644
--- a/libavcodec/vp3.c
+++ b/libavcodec/vp3.c
@@ -1950,7 +1950,7 @@ static void vp3_draw_horiz_band(Vp3DecodeContext *s, int y)
 static void await_reference_row(Vp3DecodeContext *s, Vp3Fragment *fragment,
                                 int motion_y, int y)
 {
-    ThreadFrame *ref_frame;
+    const ThreadFrame *ref_frame;
     int ref_row;
     int border = motion_y & 1;