Add UMA histogram for native audio buffer size in ms

The Android native audio code asks the OS to provide an appropriate
buffer size for real-time audio playout. We should add logging for this
value so we can see what values are used in practice.

Bug: b/157429867
Change-Id: I111a74faefc0e77b5c98921804d6625cba1b84af
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176126
Reviewed-by: Henrik Andreassson <henrika@webrtc.org>
Reviewed-by: Henrik Andreasson <henrika@chromium.org>
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31368}

modules/audio_device/android/audio_track_jni.cc

@@ -19,6 +19,7 @@
 #include "rtc_base/logging.h"
 #include "rtc_base/platform_thread.h"
 #include "system_wrappers/include/field_trial.h"
+#include "system_wrappers/include/metrics.h"
 
 namespace webrtc {
 
@@ -27,7 +28,7 @@ AudioTrackJni::JavaAudioTrack::JavaAudioTrack(
     NativeRegistration* native_reg,
     std::unique_ptr<GlobalRef> audio_track)
     : audio_track_(std::move(audio_track)),
-      init_playout_(native_reg->GetMethodId("initPlayout", "(IID)Z")),
+      init_playout_(native_reg->GetMethodId("initPlayout", "(IID)I")),
       start_playout_(native_reg->GetMethodId("startPlayout", "()Z")),
       stop_playout_(native_reg->GetMethodId("stopPlayout", "()Z")),
       set_stream_volume_(native_reg->GetMethodId("setStreamVolume", "(I)Z")),
@@ -45,8 +46,18 @@ bool AudioTrackJni::JavaAudioTrack::InitPlayout(int sample_rate, int channels) {
              nullptr);
   if (buffer_size_factor == 0)
     buffer_size_factor = 1.0;
-  return audio_track_->CallBooleanMethod(init_playout_, sample_rate, channels,
-                                         buffer_size_factor);
+  int buffer_size_bytes = audio_track_->CallIntMethod(
+      init_playout_, sample_rate, channels, buffer_size_factor);
+  if (buffer_size_bytes != -1) {
+    // To avoid division by zero, we assume the sample rate is 48k if an invalid
+    // value is found.
+    sample_rate = sample_rate <= 0 ? 48000 : sample_rate;
+    const int buffer_size_ms = (buffer_size_bytes * 1000) / (2 * sample_rate);
+    RTC_HISTOGRAM_COUNTS("WebRTC.Audio.AndroidNativeRequestedAudioBufferSizeMs",
+                         buffer_size_ms, 0, 1000, 100);
+    return true;
+  }
+  return false;
 }
 
 bool AudioTrackJni::JavaAudioTrack::StartPlayout() {

modules/audio_device/android/java/src/org/webrtc/voiceengine/WebRtcAudioTrack.java

@@ -215,7 +215,7 @@ public class WebRtcAudioTrack {
     }
   }
 
-  private boolean initPlayout(int sampleRate, int channels, double bufferSizeFactor) {
+  private int initPlayout(int sampleRate, int channels, double bufferSizeFactor) {
     threadChecker.checkIsOnValidThread();
     Logging.d(TAG,
         "initPlayout(sampleRate=" + sampleRate + ", channels=" + channels
@@ -244,14 +244,14 @@ public class WebRtcAudioTrack {
     // can happen that |minBufferSizeInBytes| contains an invalid value.
     if (minBufferSizeInBytes < byteBuffer.capacity()) {
       reportWebRtcAudioTrackInitError("AudioTrack.getMinBufferSize returns an invalid value.");
-      return false;
+      return -1;
     }
 
     // Ensure that prevision audio session was stopped correctly before trying
     // to create a new AudioTrack.
     if (audioTrack != null) {
       reportWebRtcAudioTrackInitError("Conflict with existing AudioTrack.");
-      return false;
+      return -1;
     }
     try {
       // Create an AudioTrack object and initialize its associated audio buffer.
@@ -273,7 +273,7 @@ public class WebRtcAudioTrack {
     } catch (IllegalArgumentException e) {
       reportWebRtcAudioTrackInitError(e.getMessage());
       releaseAudioResources();
-      return false;
+      return -1;
     }
 
     // It can happen that an AudioTrack is created but it was not successfully
@@ -282,11 +282,11 @@ public class WebRtcAudioTrack {
     if (audioTrack == null || audioTrack.getState() != AudioTrack.STATE_INITIALIZED) {
       reportWebRtcAudioTrackInitError("Initialization of audio track failed.");
       releaseAudioResources();
-      return false;
+      return -1;
     }
     logMainParameters();
     logMainParametersExtended();
-    return true;
+    return minBufferSizeInBytes;
   }
 
   private boolean startPlayout() {

sdk/android/src/java/org/webrtc/audio/WebRtcAudioTrack.java

@@ -183,7 +183,7 @@ class WebRtcAudioTrack {
   }
 
   @CalledByNative
-  private boolean initPlayout(int sampleRate, int channels, double bufferSizeFactor) {
+  private int initPlayout(int sampleRate, int channels, double bufferSizeFactor) {
     threadChecker.checkIsOnValidThread();
     Logging.d(TAG,
         "initPlayout(sampleRate=" + sampleRate + ", channels=" + channels
@@ -212,14 +212,14 @@ class WebRtcAudioTrack {
     // can happen that |minBufferSizeInBytes| contains an invalid value.
     if (minBufferSizeInBytes < byteBuffer.capacity()) {
       reportWebRtcAudioTrackInitError("AudioTrack.getMinBufferSize returns an invalid value.");
-      return false;
+      return -1;
     }
 
     // Ensure that prevision audio session was stopped correctly before trying
     // to create a new AudioTrack.
     if (audioTrack != null) {
       reportWebRtcAudioTrackInitError("Conflict with existing AudioTrack.");
-      return false;
+      return -1;
     }
     try {
       // Create an AudioTrack object and initialize its associated audio buffer.
@@ -241,7 +241,7 @@ class WebRtcAudioTrack {
     } catch (IllegalArgumentException e) {
       reportWebRtcAudioTrackInitError(e.getMessage());
       releaseAudioResources();
-      return false;
+      return -1;
     }
 
     // It can happen that an AudioTrack is created but it was not successfully
@@ -250,11 +250,11 @@ class WebRtcAudioTrack {
     if (audioTrack == null || audioTrack.getState() != AudioTrack.STATE_INITIALIZED) {
       reportWebRtcAudioTrackInitError("Initialization of audio track failed.");
       releaseAudioResources();
-      return false;
+      return -1;
     }
     logMainParameters();
     logMainParametersExtended();
-    return true;
+    return minBufferSizeInBytes;
   }
 
   @CalledByNative