Cast: Prefer VP8 over H.264 for hardware encoder

chrome/renderer/media/cast_rtp_stream.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/renderer/media/cast_rtp_stream.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 133 matching lines @@
 
 std::vector<CastRtpParams> SupportedAudioParams() {
   // TODO(hclam): Fill in more codecs here.
   std::vector<CastRtpParams> supported_params;
   supported_params.push_back(CastRtpParams(DefaultOpusPayload()));
   return supported_params;
 }
 
 std::vector<CastRtpParams> SupportedVideoParams() {
   std::vector<CastRtpParams> supported_params;
-  if (IsHardwareH264EncodingSupported())
-    supported_params.push_back(CastRtpParams(DefaultH264Payload()));
-  supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
+  // Prefer VP8 over H.264 for hardware encoder.
+  if (IsHardwareVP8EncodingSupported()) {
+    supported_params.push_back(CastRtpParams(DefaultVp8Payload()));

[miu, 2015/03/27 20:41:06]

It's fine to prefer the VP8 HW encoder, but I think you should also include
H.264 as a second option, to let an extension decide which to use.  Meaning,
this method should be:

std::vector<CastRtpParams> SupportedVideoParams() {
  std::vector<CastRtpParams> supported_params;

  if (IsHardwareVP8EncodingSupported())
    supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
  if (IsHardwareH264EncodingSupported())
    supported_params.push_back(CastRtpParams(DefaultH264Payload()));

  // Propose the default software VP8 encoder, if no hardware encoders are
available.
  if (supported_params.empty())
    supported_params.push_back(CastRtpParams(DefaultVp8Payload()));

  return supported_params;
}

+  } else {
+    if (IsHardwareH264EncodingSupported())
+      supported_params.push_back(CastRtpParams(DefaultH264Payload()));
+    supported_params.push_back(CastRtpParams(DefaultVp8Payload()));
+  }
   return supported_params;
 }
 
 bool ToAudioSenderConfig(const CastRtpParams& params,
                          AudioSenderConfig* config) {
   config->ssrc = params.payload.ssrc;
   config->receiver_ssrc = params.payload.feedback_ssrc;
   if (config->ssrc == config->receiver_ssrc)
     return false;
   config->min_playout_delay =
@@ skipping 396 matching lines @@
 void CastRtpStream::DidEncounterError(const std::string& message) {
   DVLOG(1) << "CastRtpStream::DidEncounterError(" << message << ") = "
            << (IsAudio() ? "audio" : "video");
   // Save the WeakPtr first because the error callback might delete this object.
   base::WeakPtr<CastRtpStream> ptr = weak_factory_.GetWeakPtr();
   error_callback_.Run(message);
   content::RenderThread::Get()->GetTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(&CastRtpStream::Stop, ptr));
 }