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Unified Diff: content/renderer/media/media_stream_audio_level_calculator.h

Issue 1721273002: MediaStream audio object graph untangling and clean-ups. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: addressed o1ka's comments Created 4 years, 10 months ago
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Index: content/renderer/media/media_stream_audio_level_calculator.h
diff --git a/content/renderer/media/media_stream_audio_level_calculator.h b/content/renderer/media/media_stream_audio_level_calculator.h
index e7d25cc5d548add19f02afa9b35796f20e0ca7ca..af9bdc88cbe8ac21e54a857f1297a4383bb6eff4 100644
--- a/content/renderer/media/media_stream_audio_level_calculator.h
+++ b/content/renderer/media/media_stream_audio_level_calculator.h
@@ -5,7 +5,9 @@
#ifndef CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
#define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_AUDIO_LEVEL_CALCULATOR_H_
-#include "base/threading/thread_checker.h"
+#include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
+#include "content/common/content_export.h"
namespace media {
class AudioBus;
@@ -13,30 +15,49 @@ class AudioBus;
namespace content {
-// This class is used by the WebRtcLocalAudioTrack to calculate the level of
-// the audio signal. And the audio level will be eventually used by the volume
+// This class is used by the WebRtcAudioCapturer to calculate the level of the
+// audio signal. And the audio level will be eventually used by the volume
// animation UI.
+//
// The algorithm used by this class is the same as how it is done in
// third_party/webrtc/voice_engine/level_indicator.cc.
-class MediaStreamAudioLevelCalculator {
+class CONTENT_EXPORT MediaStreamAudioLevelCalculator {
public:
+ // Provides thread-safe access to the current signal level. This object is
+ // intended to be passed to modules running on other threads that poll for the
+ // current signal level.
+ class Level : public base::RefCountedThreadSafe<Level> {
+ public:
+ float GetCurrent() const;
+
+ private:
+ friend class MediaStreamAudioLevelCalculator;
+ friend class base::RefCountedThreadSafe<Level>;
+
+ Level();
+ ~Level();
+
+ void Set(float level);
+
+ mutable base::Lock lock_;
+ float level_;
+ };
+
MediaStreamAudioLevelCalculator();
~MediaStreamAudioLevelCalculator();
- // Calculates the signal level of the audio data, returning the absolute value
- // of the amplitude of the signal.
- float Calculate(const media::AudioBus& audio_bus);
+ scoped_refptr<Level> level() const { return level_; }
- private:
- // Used to DCHECK that the constructor and Calculate() are always called on
- // the same audio thread. Note that the destructor will be called on a
- // different thread, which can be either the main render thread or a new
- // audio thread where WebRtcLocalAudioTrack::OnSetFormat() is called.
- base::ThreadChecker thread_checker_;
+ // Scans the audio signal in |audio_bus| and computes a new signal level
+ // exposed by Level. If |assume_nonzero_energy| is true, then a completely
+ // zero'ed-out |audio_bus| will be accounted for as having a very faint,
+ // non-zero level.
+ void Calculate(const media::AudioBus& audio_bus, bool assume_nonzero_energy);
+ private:
int counter_;
float max_amplitude_;
- float level_;
+ const scoped_refptr<Level> level_;
};
} // namespace content

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