chromium/media/base/audio_timestamp_helper.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_TIMESTAMP_HELPER_H_
#define MEDIA_BASE_AUDIO_TIMESTAMP_HELPER_H_

#include <stdint.h>

#include <optional>

#include "base/time/time.h"
#include "media/base/media_export.h"

namespace media {

// Generates timestamps for a sequence of audio sample frames. This class should
// be used any place timestamps need to be calculated for a sequence of audio
// samples. It helps avoid timestamps inaccuracies caused by rounding/truncation
// in repeated sample count to timestamp conversions.
//
// The class is constructed with samples_per_second information so that it can
// convert audio sample frame counts into timestamps. After the object is
// constructed, SetBaseTimestamp() must be called to specify the starting
// timestamp of the audio sequence. As audio samples are received, their frame
// counts are added using AddFrames(). These frame counts are accumulated by
// this class so GetTimestamp() can be used to determine the timestamp for the
// samples that have been added. GetDuration() calculates the proper duration
// values for samples added to the current timestamp. GetFramesToTarget()
// determines the number of frames that need to be added/removed from the
// accumulated frames to reach a target timestamp.
class MEDIA_EXPORT AudioTimestampHelper { … };

}  // namespace media

#endif  // MEDIA_BASE_AUDIO_TIMESTAMP_HELPER_H_