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Diffstat (limited to 'chromium/third_party/webrtc/modules/audio_processing/rms_level.h')
-rw-r--r-- | chromium/third_party/webrtc/modules/audio_processing/rms_level.h | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/chromium/third_party/webrtc/modules/audio_processing/rms_level.h b/chromium/third_party/webrtc/modules/audio_processing/rms_level.h new file mode 100644 index 00000000000..055d271bb19 --- /dev/null +++ b/chromium/third_party/webrtc/modules/audio_processing/rms_level.h @@ -0,0 +1,57 @@ +/* + * Copyright (c) 2014 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_RMS_LEVEL_H_ +#define WEBRTC_MODULES_AUDIO_PROCESSING_RMS_LEVEL_H_ + +#include "webrtc/typedefs.h" + +namespace webrtc { + +// Computes the root mean square (RMS) level in dBFs (decibels from digital +// full-scale) of audio data. The computation follows RFC 6465: +// https://tools.ietf.org/html/rfc6465 +// with the intent that it can provide the RTP audio level indication. +// +// The expected approach is to provide constant-sized chunks of audio to +// Process(). When enough chunks have been accumulated to form a packet, call +// RMS() to get the audio level indicator for the RTP header. +class RMSLevel { + public: + static const int kMinLevel = 127; + + RMSLevel(); + ~RMSLevel(); + + // Can be called to reset internal states, but is not required during normal + // operation. + void Reset(); + + // Pass each chunk of audio to Process() to accumulate the level. + void Process(const int16_t* data, int length); + + // If all samples with the given |length| have a magnitude of zero, this is + // a shortcut to avoid some computation. + void ProcessMuted(int length); + + // Computes the RMS level over all data passed to Process() since the last + // call to RMS(). The returned value is positive but should be interpreted as + // negative as per the RFC. It is constrained to [0, 127]. + int RMS(); + + private: + float sum_square_; + int sample_count_; +}; + +} // namespace webrtc + +#endif // WEBRTC_MODULES_AUDIO_PROCESSING_RMS_LEVEL_H_ + |