Add UMA reporting for audio hardware parameters.

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/compiler_specific.h"
 #include "base/message_loop.h"
+#include "base/metrics/histogram.h"
 #include "base/time.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_output_dispatcher_impl.h"
 #include "media/audio/audio_output_proxy.h"
 #include "media/audio/audio_util.h"
+#include "media/audio/sample_rates.h"
 #include "media/base/audio_pull_fifo.h"
 #include "media/base/multi_channel_resampler.h"
 
 namespace media {
 
 AudioOutputResampler::AudioOutputResampler(AudioManager* audio_manager,
                                            const AudioParameters& input_params,
                                            const AudioParameters& output_params,
                                            const base::TimeDelta& close_delay)
     : AudioOutputDispatcher(audio_manager, input_params),
@@ skipping 44 matching lines @@
               base::Unretained(this))));
     }
 
     DVLOG(1) << "I/O ratio is " << io_ratio_;
   }
 
   // TODO(dalecurtis): All this code should be merged into AudioOutputMixer once
   // we've stabilized the issues there.
   dispatcher_ = new AudioOutputDispatcherImpl(
       audio_manager, output_params, close_delay);
+
+  // Fake enum histogram to get exact integral buckets.  Expect to never see
+  // any values over 32 and even that is huge.
+  UMA_HISTOGRAM_ENUMERATION(
+      "Media.HardwareAudioBitsPerChannel", output_params.bits_per_sample(),
+      40);

[scherkus (not reviewing), 2012/09/11 16:53:31]

not worth enumifying a la sample rate?

[DaleCurtis, 2012/09/11 17:35:59]

Copy/pasted from AudioDecoderConfig. You tell me.

+  UMA_HISTOGRAM_ENUMERATION(
+      "Media.HardwareAudioChannelLayout", output_params.channel_layout(),

[scherkus (not reviewing), 2012/09/11 16:53:31]

I thought we only got hardware channel *count* and not layout?


If we do indeed track layout, to preserve accuracy of UMA data over time you'll
have to assign values to ChannelLayout + include documentation to not re-use
values (see PipelineStatus for an example)

[DaleCurtis, 2012/09/11 17:35:59]

This is all a copy paste of what's in AudioDecoderConfig? Why would I need to
add more for ChannelLayout here but not there?

We really don't have either. This code will track the input parameters
currently. If we want to track the actual hardware value I'll need to #if
WINDOWS this as well as muck with audio manager to expose that information in a
platform agnostic manner.

(We don't want to put this in GetPreferredLowLatencyBlahBlahBlah right now since
it's being handled at the output device instead of here).

[DaleCurtis, 2012/09/12 09:50:57]

Done. I'm now pulling the actual hardware channel count for Windows. 

+      CHANNEL_LAYOUT_MAX);
+  AudioSampleRate asr = media::AsAudioSampleRate(output_params.sample_rate());
+  if (asr != kUnexpectedAudioSampleRate) {
+    UMA_HISTOGRAM_ENUMERATION(
+        "Media.HardwareAudioSamplesPerSecond", asr, kUnexpectedAudioSampleRate);
+  } else {
+    UMA_HISTOGRAM_COUNTS(
+        "Media.HardwareAudioSamplesPerSecondUnexpected",
+        output_params.sample_rate());
+  }
 }
 
 AudioOutputResampler::~AudioOutputResampler() {}
 
 bool AudioOutputResampler::OpenStream() {
   // TODO(dalecurtis): Automatically revert to high latency path if OpenStream()
   // fails; use default high latency output values + rebuffering / resampling.
   return dispatcher_->OpenStream();
 }
 
@@ skipping 106 matching lines @@
     source_callback_->OnError(stream, code);
 }
 
 void AudioOutputResampler::WaitTillDataReady() {
   base::AutoLock auto_lock(source_lock_);
   if (source_callback_ && !outstanding_audio_bytes_)
     source_callback_->WaitTillDataReady();
 }
 
 }  // namespace media