VaapiVEA: Handle bitrate and frame rate negotiation from webrtc

content/common/gpu/media/vaapi_video_encode_accelerator.cc

 // Copyright 2014 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 "content/common/gpu/media/vaapi_video_encode_accelerator.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 727 matching lines @@
   cpb_size_ = bitrate_ * kCPBWindowSizeMs / 1000;
 }
 
 void VaapiVideoEncodeAccelerator::RequestEncodingParametersChangeTask(
     uint32 bitrate,
     uint32 framerate) {
   DVLOGF(2) << "bitrate: " << bitrate << " framerate: " << framerate;
   DCHECK(encoder_thread_proxy_->BelongsToCurrentThread());
   DCHECK_NE(state_, kUninitialized);
 
+  if (bitrate < 1)
+    bitrate = 1;
+  if (framerate < 1)
+    framerate = 1;

[xhwang, 2014/07/07 16:30:51]

I am not really familiar with this code, so some newbie questions:

1, Why can't webrtc change the default framerate to 1 so that VEAs don't need
this hack anymore. Otherwise, all VEAs need to do the same hack which sounds
bad.

2, What's the unit of |framerate| here, frame per second? If so, is 1 frame per
second a good choice for a default value?

+
   UpdateRates(bitrate, framerate);
 
   UpdateSPS();
   GeneratePackedSPS();
 
   // Submit new parameters along with next frame that will be processed.
   encoding_parameters_changed_ = true;
 }
 
 void VaapiVideoEncodeAccelerator::Destroy() {
@@ skipping 294 matching lines @@
 }
 
 VaapiVideoEncodeAccelerator::EncodeJob::EncodeJob()
     : coded_buffer(VA_INVALID_ID), keyframe(false) {
 }
 
 VaapiVideoEncodeAccelerator::EncodeJob::~EncodeJob() {
 }
 
 }  // namespace content