// webrtc::VideoEncoder class for WebRTC. Internally, VEA methods are
// trampolined to a private RTCVideoEncoder::Impl instance. The Impl class runs
// on the worker thread queried from the |gpu_factories_|, which is presently
-// the media thread. RTCVideoEncoder itself is run and destroyed on the thread
-// it is constructed on, which is presently the libjingle worker thread.
-// Callbacks from the Impl due to its VEA::Client notifications are also posted
-// back to RTCVideoEncoder on this thread.
+// the media thread. RTCVideoEncoder is sychronized by webrtc::VideoSender.
+// webrtc::VideoEncoder methods do not run concurrently. RTCVideoEncoder is run
+// and destroyed on the thread it is constructed on, which is presently the
+// libjingle worker thread. Encode is run on ViECaptureThread. SetRates and
+// SetChannelParameters are run on ProcessThread or the libjingle worker thread.
+// Callbacks from the Impl due to its VEA::Client notifications are posted back
+// to RTCVideoEncoder on the libjingle worker thread.
class CONTENT_EXPORT RTCVideoEncoder
: NON_EXPORTED_BASE(public webrtc::VideoEncoder) {
public: