Ability to disable the effects of |rtc_use_h264| with DisableRtcUseH264.

webrtc/modules/video_coding/codecs/h264/h264.cc

Index: webrtc/modules/video_coding/codecs/h264/h264.cc
diff --git a/webrtc/modules/video_coding/codecs/h264/h264.cc b/webrtc/modules/video_coding/codecs/h264/h264.cc
index 6f7316b10a69e9cd1db76ed0b5aa37cd15ae13fa..3da3b595d5035fd813aa32e9f328096722246fb6 100644
--- a/webrtc/modules/video_coding/codecs/h264/h264.cc
+++ b/webrtc/modules/video_coding/codecs/h264/h264.cc
@@ -11,9 +11,9 @@
 
 #include "webrtc/modules/video_coding/codecs/h264/include/h264.h"
 
-#if defined(WEBRTC_THIRD_PARTY_H264)
-#include "webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h"
+#if defined(WEBRTC_USE_H264)
 #include "webrtc/modules/video_coding/codecs/h264/h264_decoder_impl.h"
+#include "webrtc/modules/video_coding/codecs/h264/h264_encoder_impl.h"

[tommi, 2016/02/02 16:33:13]

for what do we need the encoder header?

[hbos, 2016/02/02 17:08:19]

H264Encoder::Create() and H264Decoder::Create().

[tommi, 2016/02/02 17:11:19]

ah sorry, I was thinking openh264 encode. never mind.

 #endif
 #if defined(WEBRTC_IOS)
 #include "webrtc/modules/video_coding/codecs/h264/h264_video_toolbox_decoder.h"
@@ -25,6 +25,20 @@
 
 namespace webrtc {
 
+namespace {
+
+#if defined(WEBRTC_USE_H264)

[tommi, 2016/02/02 16:33:13]

Is this flag for h264 in general or specific to openh264? Maybe we should rename
it to WEBRTC_USE_OPENH264?

[hbos, 2016/02/02 17:08:19]

It's for OpenH264 encoding + FFmpeg decoding both. The flag is called
rtc_use_h264 so I named the macro after it. I'll add a TODO about flag/macro
name.

[tommi, 2016/02/02 17:11:19]

Acknowledged.

+bool rtc_use_h264 = true;

[tommi, 2016/02/02 16:33:13]

since this is a global variable, should have the g_ prefix

[hbos, 2016/02/02 17:08:19]

Done.

+#endif
+
+}  // namespace
+
+void SetRtcUseH264(bool enable) {

[tommi, 2016/02/02 16:33:13]

I'm assuming we do not want to allow flipping this value back and forth and that
this is specifically used to disable the feature (given that it's turned on by
default).  If so, then I think we should just call this DisableOpenH264() and it
takes no parameters.

[hbos, 2016/02/02 17:08:19]

Done. (Calling it DisableRtcUseH264() after |rtc_use_h264|, could rename if/when
flag is renamed)

[tommi, 2016/02/02 17:11:19]

Acknowledged.

+#if defined(WEBRTC_USE_H264)
+  rtc_use_h264 = enable;

[tommi, 2016/02/02 16:33:13]

how do we guarantee thread safety?  Wondering if we could trip off tsan tests?

[hbos, 2016/02/02 17:08:19]

It's not, as per function comment in header.

+#endif
+}
+
 // We need this file to be C++ only so it will compile properly for all
 // platforms. In order to write ObjC specific implementations we use private
 // externs. This function is defined in h264.mm.
@@ -39,8 +53,8 @@ bool IsH264CodecSupported() {
     return true;
   }
 #endif
-#if defined(WEBRTC_THIRD_PARTY_H264)
-  return true;
+#if defined(WEBRTC_USE_H264)
+  return rtc_use_h264;
 #else
   return false;
 #endif
@@ -54,13 +68,14 @@ H264Encoder* H264Encoder::Create() {
     return new H264VideoToolboxEncoder();
   }
 #endif
-#if defined(WEBRTC_THIRD_PARTY_H264)
-  LOG(LS_INFO) << "Creating H264EncoderImpl.";
-  return new H264EncoderImpl();
-#else
+#if defined(WEBRTC_USE_H264)
+  if (rtc_use_h264) {

[tommi, 2016/02/02 16:33:13]

here, I would rather do:

RTC_[D]CHECK(rtc_use_h264);
return new H264EncoderImpl();

[hbos, 2016/02/02 17:08:19]

Done.

+    LOG(LS_INFO) << "Creating H264EncoderImpl.";
+    return new H264EncoderImpl();
+  }
+#endif
   RTC_NOTREACHED();
   return nullptr;
-#endif
 }
 
 bool H264Encoder::IsSupported() {
@@ -75,13 +90,14 @@ H264Decoder* H264Decoder::Create() {
     return new H264VideoToolboxDecoder();
   }
 #endif
-#if defined(WEBRTC_THIRD_PARTY_H264)
-  LOG(LS_INFO) << "Creating H264DecoderImpl.";
-  return new H264DecoderImpl();
-#else
+#if defined(WEBRTC_USE_H264)
+  if (rtc_use_h264) {

[tommi, 2016/02/02 16:33:13]

RTC_CHECK(rtc_use_h264)

[hbos, 2016/02/02 17:08:19]

Done.

+    LOG(LS_INFO) << "Creating H264DecoderImpl.";
+    return new H264DecoderImpl();
+  }
+#endif
   RTC_NOTREACHED();
   return nullptr;
-#endif
 }
 
 bool H264Decoder::IsSupported() {