Generate FMTP parameters for the H.264 codec.

webrtc/media/engine/webrtcvideoengine2.cc

Index: webrtc/media/engine/webrtcvideoengine2.cc
diff --git a/webrtc/media/engine/webrtcvideoengine2.cc b/webrtc/media/engine/webrtcvideoengine2.cc
index ec6b033d2f7a3862be69a9c25390d646968cfd2c..508ab19d5180ac65947d0b48d694ba1abb65bdc1 100644
--- a/webrtc/media/engine/webrtcvideoengine2.cc
+++ b/webrtc/media/engine/webrtcvideoengine2.cc
@@ -386,8 +386,15 @@ std::vector<VideoCodec> DefaultVideoCodecList() {
         VideoCodec::CreateRtxCodec(kDefaultRtxVp9PlType, kDefaultVp9PlType));
   }
   if (CodecIsInternallySupported(kH264CodecName)) {
-    codecs.push_back(MakeVideoCodecWithDefaultFeedbackParams(kDefaultH264PlType,
-                                                             kH264CodecName));
+    VideoCodec codec = MakeVideoCodecWithDefaultFeedbackParams(
+        kDefaultH264PlType, kH264CodecName);
+    // TODO(hta): Move selection of profile-level-id to codec implementation.

[nisse-webrtc, 2016/04/12 10:03:42]

This is probably not the right place for these defaults. If no configurability
is needed for now, push them down to the codec? Or else, pass in values from
above, and move the default values there?

[hta-webrtc, 2016/04/12 11:21:38]

I couldn't find a better place for now. 

The classes below are VideoCodec() and Codec(). Neither is appropriate for
codec-specific functionality. I was aghast to find that the Codec() class even
allows changing the name of the codec - and that there is code that depends on
that.

There is no "above" that knows about types of codecs - this function is called
DefaultVideoCodecList.

It's more proper to bind this info to the implementation, but the VideoCodec
class doesn't point to the implementation, and webrtcsdp.cc doesn't know about
the classes that contain the implementation, as far as I could tell.

As I said in the CL description - this patch is not pretty. Refactoring needed.

+    // TODO(hta): Set FMTP parameters for all codecs of type H264.
+    codec.SetParam(kH264FmtpProfileLevelId,
+                   kH264ProfileLevelConstrainedBaseline);
+    codec.SetParam(kH264FmtpLevelAsymmetryAllowed, "1");
+    codec.SetParam(kH264FmtpPacketizationMode, "1");
+    codecs.push_back(codec);
     codecs.push_back(
         VideoCodec::CreateRtxCodec(kDefaultRtxH264PlType, kDefaultH264PlType));
   }