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// Copyright 2019 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.
#ifndef MEDIA_BLINK_SMOOTHNESS_HELPER_H_
#define MEDIA_BLINK_SMOOTHNESS_HELPER_H_
#include <memory>
#include "media/base/buffering_state.h"
#include "media/base/pipeline_status.h"
#include "media/blink/media_blink_export.h"
#include "media/learning/common/labelled_example.h"
namespace media {
namespace learning {
class LearningTaskController;
}
// Helper class to construct learning observations about the smoothness of a
// video playback. Currently measures the worst-case frame drop ratio observed
// among fixed-length segments.
class MEDIA_BLINK_EXPORT SmoothnessHelper {
public:
// Callback that provides the number of dropped / decoded frames since some
// point in the past. We assume that these values are comparable during
// playback, so that we can compute deltas.
class Client {
public:
virtual ~Client() {}
virtual unsigned DecodedFrameCount() const = 0;
virtual unsigned DroppedFrameCount() const = 0;
};
virtual ~SmoothnessHelper();
// Return the features that we were constructed with.
const learning::FeatureVector& features() const { return features_; }
// Notify us that an NNR has occurred.
virtual void NotifyNNR() = 0;
// |features| are the features that we'll use for any labelled examples that
// we create. They should be features that could be captured at the time a
// prediction would be needed.
static std::unique_ptr<SmoothnessHelper> Create(
std::unique_ptr<learning::LearningTaskController> bad_controller,
std::unique_ptr<learning::LearningTaskController> nnr_controller,
const learning::FeatureVector& features,
Client* player);
// We split playbacks up into |kSegmentSize| units, and record the worst
// dropped frame ratio over all segments of a playback. A playback is not
// recorded if it doesn't contain at least one full segment.
static base::TimeDelta SegmentSizeForTesting();
protected:
SmoothnessHelper(const learning::FeatureVector& features);
learning::FeatureVector features_;
};
} // namespace media
#endif // MEDIA_BLINK_SMOOTHNESS_HELPER_H_
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