diff --git a/modules/video_coding/BUILD.gn b/modules/video_coding/BUILD.gn
index 0ed9da22a9..bff40c9620 100644
--- a/modules/video_coding/BUILD.gn
+++ b/modules/video_coding/BUILD.gn
@@ -301,9 +301,6 @@ rtc_static_library("webrtc_h264") {
 
   if (rtc_use_h264) {
     defines += [ "WEBRTC_USE_H264" ]
-    if (rtc_initialize_ffmpeg) {
-      defines += [ "WEBRTC_INITIALIZE_FFMPEG" ]
-    }
     sources += [
       "codecs/h264/h264_decoder_impl.cc",
       "codecs/h264/h264_decoder_impl.h",
@@ -316,11 +313,6 @@ rtc_static_library("webrtc_h264") {
       "//third_party/openh264:encoder",
     ]
 
-    # TODO(bugs.webrtc.org/9352): Stop using ffmpeg deprecated functions.
-    if (!is_win) {
-      cflags = [ "-Wno-deprecated-declarations" ]
-    }
-
     if (!build_with_mozilla) {
       deps += [ "../../media:rtc_media_base" ]
     }
diff --git a/modules/video_coding/codecs/h264/h264_decoder_impl.cc b/modules/video_coding/codecs/h264/h264_decoder_impl.cc
index a2be91ca07..e91def4e03 100644
--- a/modules/video_coding/codecs/h264/h264_decoder_impl.cc
+++ b/modules/video_coding/codecs/h264/h264_decoder_impl.cc
@@ -45,21 +45,6 @@ enum H264DecoderImplEvent {
   kH264DecoderEventMax = 16,
 };
 
-#if defined(WEBRTC_INITIALIZE_FFMPEG)
-
-rtc::CriticalSection ffmpeg_init_lock;
-bool ffmpeg_initialized = false;
-
-void InitializeFFmpeg() {
-  rtc::CritScope cs(&ffmpeg_init_lock);
-  if (!ffmpeg_initialized) {
-    av_register_all();
-    ffmpeg_initialized = true;
-  }
-}
-
-#endif  // defined(WEBRTC_INITIALIZE_FFMPEG)
-
 }  // namespace
 
 int H264DecoderImpl::AVGetBuffer2(
@@ -171,18 +156,6 @@ int32_t H264DecoderImpl::InitDecode(const VideoCodec* codec_settings,
     return WEBRTC_VIDEO_CODEC_ERR_PARAMETER;
   }
 
-  // FFmpeg must have been initialized (with |av_register_all|) before we
-  // proceed. |InitializeFFmpeg| does this, which makes sense for WebRTC
-  // standalone. In other cases, such as Chromium, FFmpeg is initialized
-  // externally and calling |InitializeFFmpeg| would be thread-unsafe and result
-  // in FFmpeg being initialized twice, which could break other FFmpeg usage.
-  // See the |rtc_initialize_ffmpeg| flag.
-#if defined(WEBRTC_INITIALIZE_FFMPEG)
-  // Make sure FFmpeg has been initialized. Subsequent |InitializeFFmpeg| calls
-  // do nothing.
-  InitializeFFmpeg();
-#endif
-
   // Release necessary in case of re-initializing.
   int32_t ret = Release();
   if (ret != WEBRTC_VIDEO_CODEC_OK) {
diff --git a/webrtc.gni b/webrtc.gni
index bdbc2dd752..3b495080a9 100644
--- a/webrtc.gni
+++ b/webrtc.gni
@@ -122,8 +122,7 @@ declare_args() {
   # all platforms except Android and iOS. Because FFmpeg can be built
   # with/without H.264 support, |ffmpeg_branding| has to separately be set to a
   # value that includes H.264, for example "Chrome". If FFmpeg is built without
-  # H.264, compilation succeeds but |H264DecoderImpl| fails to initialize. See
-  # also: |rtc_initialize_ffmpeg|.
+  # H.264, compilation succeeds but |H264DecoderImpl| fails to initialize.
   # CHECK THE OPENH264, FFMPEG AND H.264 LICENSES/PATENTS BEFORE BUILDING.
   # http://www.openh264.org, https://www.ffmpeg.org/
   rtc_use_h264 = proprietary_codecs && !is_android && !is_ios
@@ -142,13 +141,6 @@ declare_args() {
   # as data dependencies. This is to enable memcheck execution on swarming bots.
   rtc_use_memcheck = false
 
-  # FFmpeg must be initialized for |H264DecoderImpl| to work. This can be done
-  # by WebRTC during |H264DecoderImpl::InitDecode| or externally. FFmpeg must
-  # only be initialized once. Projects that initialize FFmpeg externally, such
-  # as Chromium, must turn this flag off so that WebRTC does not also
-  # initialize.
-  rtc_initialize_ffmpeg = !build_with_chromium
-
   # Disable this to build without support for built-in software codecs.
   rtc_use_builtin_sw_codecs = true