Work on improving PpbAudioConfig:RecommendSampleFrameCount

content/renderer/pepper_plugin_delegate_impl.cc

 // Copyright (c) 2012 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/renderer/pepper_plugin_delegate_impl.h"
 
 #include <cmath>
 #include <queue>
 
 #include "base/bind.h"
@@ skipping 18 matching lines @@
 #include "content/common/pepper_messages.h"
 #include "content/common/quota_dispatcher.h"
 #include "content/common/view_messages.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/renderer/content_renderer_client.h"
 #include "content/renderer/gamepad_shared_memory_reader.h"
 #include "content/renderer/gpu/command_buffer_proxy.h"
 #include "content/renderer/gpu/gpu_channel_host.h"
 #include "content/renderer/gpu/renderer_gl_context.h"
 #include "content/renderer/gpu/webgraphicscontext3d_command_buffer_impl.h"
+#include "content/renderer/media/audio_hardware.h"
 #include "content/renderer/media/audio_input_message_filter.h"
 #include "content/renderer/media/audio_message_filter.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
 #include "content/renderer/p2p/p2p_transport_impl.h"
 #include "content/renderer/pepper_platform_context_3d_impl.h"
 #include "content/renderer/pepper_platform_video_decoder_impl.h"
 #include "content/renderer/render_thread_impl.h"
 #include "content/renderer/render_view_impl.h"
 #include "content/renderer/render_widget_fullscreen_pepper.h"
 #include "content/renderer/webplugin_delegate_proxy.h"
@@ skipping 175 matching lines @@
   // Our ID on the MessageFilter. THIS MUST ONLY BE ACCESSED ON THE I/O THREAD
   // or else you could race with the initialize function which sets it.
   int32 stream_id_;
 
   base::MessageLoopProxy* main_message_loop_proxy_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformAudioImpl);
 };
 
 bool PlatformAudioImpl::Initialize(
     uint32_t sample_rate, uint32_t sample_count,

[dmichael (off chromium), 2012/01/24 16:54:38]

I was confused before when you asked me if we had any way "in WebKit" to handle
different versions separately. In src/webkit/plugins/ppapi, we can certainly
handle that, though it is mostly manual (having distinct methods suffixed with
the version number, which are called appropriately from the thunk layer).

I think it would be safer to do that, even if it requires plumbing to get the
information to this point of the code. It might even be worth wrapping up the
sample rate and sample count with the version information in to an internal
"AudioConfig" or "AudioParams" object so you don't have to touch so many
function signatures next time you have to make this kind of change.

[nfullagar, 2012/01/24 19:14:58]

I did try a couple of dry runs to plumb more information regarding which
interface (new or old) called down to this function, but it ended up touching so
many files that in both cases I backed out.  I agree that long term we'll want
some pattern or mechanism to do this for ppapi (in general, not just audio,) but
that's beyond the scope of this CL.  I've talked to Chris and Erik about the
approach taken in this CL; it seems reasonable (and some of this approach was
suggested by Chris, iirc.)  The main concern is if an application built to the
1.0 interface happened to use the combination of recommended sample rate and
sample frame count, it might get the new back end on some platforms instead of
the old back end.  But from the application's perspective, the behavior should
be the same.

On 2012/01/24 16:54:38, dmichael wrote:

     webkit::ppapi::PluginDelegate::PlatformAudioCommonClient* client) {
 
   DCHECK(client);
   // Make sure we don't call init more than once.
   DCHECK_EQ(0, stream_id_);
 
   client_ = client;
 
   AudioParameters params;
-  params.format = AudioParameters::AUDIO_PCM_LINEAR;
+  // Use the low latency back end if the client request is compatible.
+  if (sample_rate == audio_hardware::GetOutputSampleRate() &&
+      sample_count % audio_hardware::GetOutputBufferSize() == 0)
+    params.format = AudioParameters::AUDIO_PCM_LOW_LATENCY;
+  else
+    params.format = AudioParameters::AUDIO_PCM_LINEAR;
   params.channels = 2;
   params.sample_rate = sample_rate;
   params.bits_per_sample = 16;
   params.samples_per_packet = sample_count;
 
   ChildProcess::current()->io_message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&PlatformAudioImpl::InitializeOnIOThread, this, params));
   return true;
 }
@@ skipping 1910 matching lines @@
 
 bool PepperPluginDelegateImpl::CanUseSocketAPIs() {
   WebView* webview = render_view_->webview();
   WebFrame* main_frame = webview ? webview->mainFrame() : NULL;
   GURL url(main_frame ? GURL(main_frame->document().url()) : GURL());
   if (!url.is_valid())
     return false;
 
   return content::GetContentClient()->renderer()->AllowSocketAPI(url);
 }