Recreate WebrtcVideoSendStream if screen content setting is changed.

webrtc/media/engine/webrtcvideoengine2.cc

 /*
  *  Copyright (c) 2014 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 1570 matching lines @@
   }
 
   parameters_.config.rtp.c_name = sp.cname;
   if (rtp_extensions) {
     parameters_.config.rtp.extensions = *rtp_extensions;
   }
   parameters_.config.rtp.rtcp_mode = send_params.rtcp.reduced_size
                                          ? webrtc::RtcpMode::kReducedSize
                                          : webrtc::RtcpMode::kCompound;
   if (codec_settings) {
-    SetCodec(*codec_settings);
+    SetCodec(*codec_settings, false);

[pthatcher1, 2017/02/27 18:30:38]

This would be much more clear as:

bool force_encoder_allocation = false;
SetCodec(*codec_settings, force_encoder_allocation);

[sprang_webrtc, 2017/02/27 19:37:23]

Done.

   }
 }
 
 WebRtcVideoChannel2::WebRtcVideoSendStream::~WebRtcVideoSendStream() {
   if (stream_ != NULL) {
     call_->DestroyVideoSendStream(stream_);
   }
   DestroyVideoEncoder(&allocated_encoder_);
 }
 
 bool WebRtcVideoChannel2::WebRtcVideoSendStream::SetVideoSend(
     bool enable,
     const VideoOptions* options,
     rtc::VideoSourceInterface<webrtc::VideoFrame>* source) {
   TRACE_EVENT0("webrtc", "WebRtcVideoSendStream::SetVideoSend");
   RTC_DCHECK_RUN_ON(&thread_checker_);
 
   // Ignore |options| pointer if |enable| is false.
   bool options_present = enable && options;
 
   if (options_present) {
     VideoOptions old_options = parameters_.options;
     parameters_.options.SetAll(*options);
+    if (parameters_.options.is_screencast.value_or(false) !=
+            old_options.is_screencast.value_or(false) &&
+        parameters_.codec_settings) {
+      // If screen content settings change, we may need to recreate the codec
+      // instance so that the correct type is used.
+      SetCodec(*parameters_.codec_settings, true);

[pthatcher1, 2017/02/27 18:30:38]

And here:

bool force_encoder_allocation = true;
SetCodec(*codec_settings, force_encoder_allocation);

[sprang_webrtc, 2017/02/27 19:37:23]

Done.

+      // Mark screenshare parameter as being updated, then test for any other
+      // changes that may require codec reconfiguration.
+      old_options.is_screencast = options->is_screencast;
+    }
     if (parameters_.options != old_options) {
       ReconfigureEncoder();
     }
   }
 
   if (source_ && stream_) {
     stream_->SetSource(
         nullptr, webrtc::VideoSendStream::DegradationPreference::kBalanced);
   }
   // Switch to the new source.
@@ skipping 13 matching lines @@
   return true;
 }
 
 const std::vector<uint32_t>&
 WebRtcVideoChannel2::WebRtcVideoSendStream::GetSsrcs() const {
   return ssrcs_;
 }
 
 WebRtcVideoChannel2::WebRtcVideoSendStream::AllocatedEncoder
 WebRtcVideoChannel2::WebRtcVideoSendStream::CreateVideoEncoder(
-    const VideoCodec& codec) {
+    const VideoCodec& codec,
+    bool force_encoder_allocation) {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   // Do not re-create encoders of the same type.
-  if (codec == allocated_encoder_.codec &&
+  if (!force_encoder_allocation && codec == allocated_encoder_.codec &&
       allocated_encoder_.encoder != nullptr) {
     return allocated_encoder_;
   }
 
   // Try creating external encoder.
   if (external_encoder_factory_ != nullptr &&
       FindMatchingCodec(external_encoder_factory_->supported_codecs(), codec)) {
     webrtc::VideoEncoder* encoder =
         external_encoder_factory_->CreateVideoEncoder(codec);
     if (encoder != nullptr)
@@ skipping 26 matching lines @@
 void WebRtcVideoChannel2::WebRtcVideoSendStream::DestroyVideoEncoder(
     AllocatedEncoder* encoder) {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   if (encoder->external) {
     external_encoder_factory_->DestroyVideoEncoder(encoder->external_encoder);
   }
   delete encoder->encoder;
 }
 
 void WebRtcVideoChannel2::WebRtcVideoSendStream::SetCodec(
-    const VideoCodecSettings& codec_settings) {
+    const VideoCodecSettings& codec_settings,
+    bool force_encoder_allocation) {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   parameters_.encoder_config = CreateVideoEncoderConfig(codec_settings.codec);
   RTC_DCHECK_GT(parameters_.encoder_config.number_of_streams, 0);
 
-  AllocatedEncoder new_encoder = CreateVideoEncoder(codec_settings.codec);
+  AllocatedEncoder new_encoder =
+      CreateVideoEncoder(codec_settings.codec, force_encoder_allocation);
   parameters_.config.encoder_settings.encoder = new_encoder.encoder;
   parameters_.config.encoder_settings.full_overuse_time = new_encoder.external;
   parameters_.config.encoder_settings.payload_name = codec_settings.codec.name;
   parameters_.config.encoder_settings.payload_type = codec_settings.codec.id;
   if (new_encoder.external) {
     webrtc::VideoCodecType type =
         webrtc::PayloadNameToCodecType(codec_settings.codec.name)
             .value_or(webrtc::kVideoCodecUnknown);
     parameters_.config.encoder_settings.internal_source =
         external_encoder_factory_->EncoderTypeHasInternalSource(type);
@@ skipping 46 matching lines @@
   if (params.max_bandwidth_bps) {
     parameters_.max_bitrate_bps = *params.max_bandwidth_bps;
     ReconfigureEncoder();
   }
   if (params.conference_mode) {
     parameters_.conference_mode = *params.conference_mode;
   }
 
   // Set codecs and options.
   if (params.codec) {
-    SetCodec(*params.codec);
+    SetCodec(*params.codec, false);
     recreate_stream = false;  // SetCodec has already recreated the stream.
   } else if (params.conference_mode && parameters_.codec_settings) {
-    SetCodec(*parameters_.codec_settings);
+    SetCodec(*parameters_.codec_settings, false);

[pthatcher1, 2017/02/27 18:30:38]

And these two:

bool force_encoder_allocation = false;
SetCodec(..., force_encoder_allocation);

[sprang_webrtc, 2017/02/27 19:37:23]

Done.

     recreate_stream = false;  // SetCodec has already recreated the stream.
   }
   if (recreate_stream) {
     LOG(LS_INFO) << "RecreateWebRtcStream (send) because of SetSendParameters";
     RecreateWebRtcStream();
   }
 }
 
 bool WebRtcVideoChannel2::WebRtcVideoSendStream::SetRtpParameters(
     const webrtc::RtpParameters& new_parameters) {
@@ skipping 743 matching lines @@
         rtx_mapping[video_codecs[i].codec.id] !=
             ulpfec_config.red_payload_type) {
       video_codecs[i].rtx_payload_type = rtx_mapping[video_codecs[i].codec.id];
     }
   }
 
   return video_codecs;
 }
 
 }  // namespace cricket