Fix the choppiness for the pulse impl when using a smaller buffer size like 512 samples

media/audio/pulse/pulse_output.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 "media/audio/pulse/pulse_output.h"
 
 #include <pulse/pulseaudio.h>
 
 #include "base/message_loop.h"
 #include "media/audio/audio_manager_base.h"
@@ skipping 270 matching lines @@
     if (pa_stream_write(pa_stream_, buffer, bytes_to_fill, NULL, 0LL,
                         PA_SEEK_RELATIVE) < 0) {
       if (source_callback_) {
         source_callback_->OnError(this, pa_context_errno(pa_context_));
       }
     }
 
     bytes_remaining -= bytes_to_fill;
     current_frame = frames_to_fill;
   }
+
+  size_t avialable_space = pa_stream_writable_size(pa_stream_);

[DaleCurtis, 2013/02/25 19:01:29]

s/avialable_space/available_space/

[no longer working on chromium, 2013/02/25 20:03:19]

Sorry, I will change it to writable_space

+  if (avialable_space >= static_cast<size_t>(params_.GetBytesPerBuffer())) {
+    if (source_callback_)
+      source_callback_->WaitTillDataReady();
+
+    FulfillWriteRequest(params_.GetBytesPerBuffer());

[DaleCurtis, 2013/02/25 19:01:29]

Hmm, won't this cause faster than normal playback?  Can you try this with some
flash and html5 videos?

[no longer working on chromium, 2013/02/25 20:03:19]

It should not cause fast playback, since we query the pulse server on the
writable space and write data to the driver, and the pulse is still playing
sound in its normal speed.

I have already tried some html5 sounds, webrtc and webaudio, they all sound
great (and much better for webrtc), and will do some more tests on flash
tomorrow.

+  }
 }
 
 void PulseAudioOutputStream::Start(AudioSourceCallback* callback) {
   DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
   CHECK(callback);
   CHECK(pa_stream_);
 
   AutoPulseLock auto_lock(pa_mainloop_);
 
   // Ensure the context and stream are ready.
@@ skipping 38 matching lines @@
   volume_ = static_cast<float>(volume);
 }
 
 void PulseAudioOutputStream::GetVolume(double* volume) {
   DCHECK(manager_->GetMessageLoop()->BelongsToCurrentThread());
 
   *volume = volume_;
 }
 
 }  // namespace media