contrib: ffmpeg: disable non-h264 hwaccels (fixes #8537)

Better fall back to software decoding than crash.

contrib/src/ffmpeg/rules.mak

@@ -96,7 +96,6 @@ endif
 # Linux
 ifdef HAVE_LINUX
 FFMPEGCONF += --target-os=linux --enable-pic
-
 endif
 
 # Windows
@@ -118,6 +117,12 @@ else # !Windows
 FFMPEGCONF += --enable-pthreads
 endif
 
+# Disable mpegvideo-based hwaccel - known broken
+FFMPEGCONF += \
+	$(foreach codec,h263 mpeg1 mpeg2 mpeg4 vc1 wmv3,\
+		$(foreach api,dxva2 vaapi vdpau,\
+			--disable-hwaccel=$(codec)_$(api)))
+
 # Build
 PKGS += ffmpeg
 ifeq ($(call need_pkg,"libavcodec >= 54.25.0 libavformat >= 53.21.0 libswscale"),)