Use AVOnce as a static variable consistently

Using AVOnce as a stack variable makes no sense as the state is lost
when the function exits.

This fixes repeated calls to av(filter/device)_register_all

1 files changed, 1 insertions, 1 deletions

diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 62661d14a4..b3ffe0f2b6 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -385,7 +385,7 @@ static void register_all(void)
 
 void av_register_all(void)
 {
-    AVOnce control = AV_ONCE_INIT;
+    static AVOnce control = AV_ONCE_INIT;
 
     ff_thread_once(&control, register_all);
 }