diff -up firefox-128.0/media/ffvpx/libavcodec/allcodecs.c.mozilla-bmo1789216-disable-av1 firefox-128.0/media/ffvpx/libavcodec/allcodecs.c
--- firefox-128.0/media/ffvpx/libavcodec/allcodecs.c.mozilla-bmo1789216-disable-av1	2024-06-12 15:03:01.000000000 +0200
+++ firefox-128.0/media/ffvpx/libavcodec/allcodecs.c	2024-06-13 11:44:10.637215674 +0200
@@ -764,8 +764,11 @@ extern const FFCodec ff_libaribb24_decod
 extern const FFCodec ff_libcelt_decoder;
 extern const FFCodec ff_libcodec2_encoder;
 extern const FFCodec ff_libcodec2_decoder;
+#if CONFIG_MOZ_AV1
 extern const FFCodec ff_libdav1d_decoder;
 extern const FFCodec ff_libdavs2_decoder;
+extern const FFCodec ff_libuavs3d_decoder;
+#endif
 extern const FFCodec ff_libfdk_aac_encoder;
 extern const FFCodec ff_libfdk_aac_decoder;
 extern const FFCodec ff_libgsm_encoder;
@@ -793,7 +796,6 @@ extern const FFCodec ff_libspeex_decoder
 extern const FFCodec ff_libsvtav1_encoder;
 extern const FFCodec ff_libtheora_encoder;
 extern const FFCodec ff_libtwolame_encoder;
-extern const FFCodec ff_libuavs3d_decoder;
 extern const FFCodec ff_libvo_amrwbenc_encoder;
 extern const FFCodec ff_libvorbis_encoder;
 extern const FFCodec ff_libvorbis_decoder;
diff -up firefox-128.0/media/ffvpx/libavcodec/codec_list.c.mozilla-bmo1789216-disable-av1 firefox-128.0/media/ffvpx/libavcodec/codec_list.c
--- firefox-128.0/media/ffvpx/libavcodec/codec_list.c.mozilla-bmo1789216-disable-av1	2024-06-13 11:40:12.668924117 +0200
+++ firefox-128.0/media/ffvpx/libavcodec/codec_list.c	2024-06-13 11:44:41.411253372 +0200
@@ -11,12 +11,14 @@ static const FFCodec * const codec_list[
 #if CONFIG_MP3_DECODER
     &ff_mp3_decoder,
 #endif
+#if CONFIG_MOZ_AV1
 #if CONFIG_LIBDAV1D
     &ff_libdav1d_decoder,
 #endif
 #if CONFIG_AV1_DECODER
     &ff_av1_decoder,
 #endif
+#endif
 #if CONFIG_LIBVORBIS_DECODER
     &ff_libvorbis_decoder,
 #endif
diff -up firefox-128.0/media/ffvpx/libavcodec/moz.build.mozilla-bmo1789216-disable-av1 firefox-128.0/media/ffvpx/libavcodec/moz.build
--- firefox-128.0/media/ffvpx/libavcodec/moz.build.mozilla-bmo1789216-disable-av1	2024-06-13 11:40:12.669924118 +0200
+++ firefox-128.0/media/ffvpx/libavcodec/moz.build	2024-06-13 11:45:22.867304151 +0200
@@ -120,16 +120,15 @@ if not CONFIG['MOZ_FFVPX_AUDIOONLY']:
         'vpx_rac.c',
     ]
 
-    if CONFIG["MOZ_SYSTEM_AV1"]:
-        CFLAGS += CONFIG['MOZ_SYSTEM_LIBDAV1D_CFLAGS']
-        CFLAGS += CONFIG['MOZ_SYSTEM_LIBAOM_CFLAGS']
-        OS_LIBS += CONFIG['MOZ_SYSTEM_LIBDAV1D_LIBS']
-        OS_LIBS += CONFIG['MOZ_SYSTEM_LIBAOM_LIBS']
-    else:
+    if CONFIG["MOZ_AV1"]:
         USE_LIBS += [
             'dav1d',
             'media_libdav1d_asm',
         ]
+        SOURCES += [
+            'libdav1d.c',
+        ]
+
 
     if CONFIG["MOZ_WIDGET_TOOLKIT"] == "gtk":
         LOCAL_INCLUDES += ['/media/mozva']