Work on improving PpbAudioConfig:RecommendSampleFrameCount

ppapi/cpp/audio_config.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
 #ifndef PPAPI_CPP_AUDIO_CONFIG_H_
 #define PPAPI_CPP_AUDIO_CONFIG_H_
 
 #include "ppapi/c/ppb_audio_config.h"
 #include "ppapi/c/pp_stdint.h"
 #include "ppapi/cpp/resource.h"
 
@@ skipping 56 matching lines @@
   /// one instance of a module.
   /// @param[in] sample_rate A <code>PP_AudioSampleRate</code> which is either
   /// <code>PP_AUDIOSAMPLERATE_44100</code> or
   /// <code>PP_AUDIOSAMPLERATE_48000</code>.
   /// @param[in] sample_frame_count A uint32_t frame count returned from the
   /// <code>RecommendSampleFrameCount</code> function.
   AudioConfig(Instance* instance,
               PP_AudioSampleRate sample_rate,
               uint32_t sample_frame_count);
 
+  /// RecommendSampleRate() returns the native sample rate used by the
+  /// audio system.  Applications that use the recommended sample rate might
+  /// obtain lower latency and higher fidelity output.
+  static PP_AudioSampleRate RecommendSampleRate(Instance* instance);
+
   /// RecommendSampleFrameCount() returns a supported frame count closest to
   /// the requested count. The sample frame count determines the overall
   /// latency of audio. Smaller frame counts will yield lower latency, but
   /// higher CPU utilization. Supported sample frame counts will vary by
   /// hardware and system (consider that the local system might be anywhere
   /// from a cell phone or a high-end audio workstation). Sample counts less
   /// than <code>PP_AUDIOMINSAMPLEFRAMECOUNT</code> and greater than
   /// <code>PP_AUDIOMAXSAMPLEFRAMECOUNT</code> are never supported on any
   /// system, but values in between aren't necessarily valid. This function
   /// will return a supported count closest to the requested value for use in
   /// the constructor.
   ///
- /// @param[in] sample_rate A <code>PP_AudioSampleRate</code> which is either
+  /// @param[in] instance A pointer to an <code>Instance</code> identifying
+  /// one instance of a module.
+  /// @param[in] sample_rate A <code>PP_AudioSampleRate</code> which is either
   /// <code>PP_AUDIOSAMPLERATE_44100</code> or
   /// <code>PP_AUDIOSAMPLERATE_48000</code>.
   /// @param[in] requested_sample_frame_count A uint_32t requested frame count.
   ///
   /// @return A uint32_t containing the recommended sample frame count if
   /// successful. If the sample frame count or bit rate is not supported,
   /// this function will fail and return 0.
   static uint32_t RecommendSampleFrameCount(
+      Instance* instance,
       PP_AudioSampleRate sample_rate,
       uint32_t requested_sample_frame_count);
 
   /// Getter function for returning the internal
   /// <code>PP_AudioSampleRate</code> enum.
   ///
   /// @return The <code>PP_AudioSampleRate</code> enum.
   PP_AudioSampleRate sample_rate() const { return sample_rate_; }
 
   /// Getter function for returning the internal sample frame count.
   ///
   /// @return A uint32_t containing the sample frame count.
   uint32_t sample_frame_count() { return sample_frame_count_; }
 
  private:
   PP_AudioSampleRate sample_rate_;
   uint32_t sample_frame_count_;
 };
 
 }  // namespace pp
 
 #endif  // PPAPI_CPP_AUDIO_CONFIG_H_