Reland 10952007: Pass through small buffer sizes without FIFO on Linux

media/audio/audio_output_resampler.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/audio_output_resampler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 181 matching lines @@
   }
 
   Initialize();
 }
 
 AudioOutputResampler::~AudioOutputResampler() {}
 
 void AudioOutputResampler::Initialize() {
   io_ratio_ = 1;
 
+  double in_buffer_s = static_cast<double>(params_.frames_per_buffer()) /
+      static_cast<double>(params_.sample_rate());
+  double out_buffer_s =
+      static_cast<double>(output_params_.frames_per_buffer()) /
+          static_cast<double>(output_params_.sample_rate());
+  if (in_buffer_s != out_buffer_s) {
+    int out_buffer_size = static_cast<int>(
+        in_buffer_s * output_params_.sample_rate() + 0.5);
+    output_params_.Reset(output_params_.format(),
+                           output_params_.channel_layout(),
+                           output_params_.sample_rate(),
+                           output_params_.bits_per_sample(),
+                           out_buffer_size);
+  }

[Chris Rogers, 2012/09/18 17:36:29]

Why do we need special logic here when we have
AudioManagerBase::GetPreferredLowLatencyOutputStreamParameters().  Can't this
method be made to do the right thing for all platforms?

   // TODO(dalecurtis): Add channel remixing.  http://crbug.com/138762
   DCHECK_EQ(params_.channels(), output_params_.channels());
   // Only resample or rebuffer if the input parameters don't match the output
   // parameters to avoid any unnecessary work.
   if (params_.channels() != output_params_.channels() ||
       params_.sample_rate() != output_params_.sample_rate() ||
       params_.bits_per_sample() != output_params_.bits_per_sample() ||
       params_.frames_per_buffer() != output_params_.frames_per_buffer()) {
     if (params_.sample_rate() != output_params_.sample_rate()) {
       double io_sample_rate_ratio = params_.sample_rate() /
@@ skipping 236 matching lines @@
     source_callback_->OnError(stream, code);
 }
 
 void OnMoreDataResampler::WaitTillDataReady() {
   base::AutoLock auto_lock(source_lock_);
   if (source_callback_ && !outstanding_audio_bytes_)
     source_callback_->WaitTillDataReady();
 }
 
 }  // namespace media