Adding audio only mode to video loopback test.

webrtc/video/video_loopback.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 178 matching lines @@
 
 DEFINE_bool(allow_reordering, false, "Allow packet reordering to occur");
 
 DEFINE_bool(use_fec, false, "Use forward error correction.");
 
 DEFINE_bool(audio, false, "Add audio stream");
 
 DEFINE_bool(audio_video_sync, false, "Sync audio and video stream (no effect if"
     " audio is false)");
 
+DEFINE_bool(mute_video, false, "Mute video stream");

[stefan-webrtc, 2016/09/07 13:12:10]

Can we call this "video" instead to align it with "audio"?

[minyue-webrtc, 2016/09/08 15:38:24]

Done.

+
 DEFINE_string(
     force_fieldtrials,
     "",
     "Field trials control experimental feature code which can be forced. "
     "E.g. running with --force_fieldtrials=WebRTC-FooFeature/Enable/"
     " will assign the group Enable to field trial WebRTC-FooFeature. Multiple "
     "trials are separated by \"/\"");
 
 // Video-specific flags.
 DEFINE_string(clip,
@@ skipping 15 matching lines @@
   pipe_config.delay_standard_deviation_ms = flags::StdPropagationDelayMs();
   pipe_config.allow_reordering = flags::FLAGS_allow_reordering;
 
   Call::Config::BitrateConfig call_bitrate_config;
   call_bitrate_config.min_bitrate_bps = flags::MinBitrateKbps() * 1000;
   call_bitrate_config.start_bitrate_bps = flags::StartBitrateKbps() * 1000;
   call_bitrate_config.max_bitrate_bps = flags::MaxBitrateKbps() * 1000;
 
   VideoQualityTest::Params params;
   params.common = {flags::FLAGS_send_side_bwe, call_bitrate_config};
-  params.video = {true,
+  params.video = {!flags::FLAGS_mute_video,
                   flags::Width(),
                   flags::Height(),
                   flags::Fps(),
                   flags::MinBitrateKbps() * 1000,
                   flags::TargetBitrateKbps() * 1000,
                   flags::MaxBitrateKbps() * 1000,
                   flags::FLAGS_suspend_below_min_bitrate,
                   flags::Codec(),
                   flags::NumTemporalLayers(),
                   flags::SelectedTL(),
@@ skipping 26 matching lines @@
 }  // namespace webrtc
 
 int main(int argc, char* argv[]) {
   ::testing::InitGoogleTest(&argc, argv);
   google::ParseCommandLineFlags(&argc, &argv, true);
   webrtc::test::InitFieldTrialsFromString(
       webrtc::flags::FLAGS_force_fieldtrials);
   webrtc::test::RunTest(webrtc::Loopback);
   return 0;
 }