1 /*
2  * Copyright 2021 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef PLAYBACK_DURATION_ACCUMULATOR_H_
18 
19 namespace android {
20 
21 // Accumulates playback duration by processing render times of individual frames and by ignoring
22 // frames rendered during inactive playbacks such as seeking, pausing, or re-buffering.
23 class PlaybackDurationAccumulator {
24 private:
25     // Controls the maximum delta between render times before considering the playback is not
26     // active and has stalled.
27     static const int64_t MAX_PRESENTATION_DURATION_NS = 500 * 1000 * 1000;
28 
29 public:
PlaybackDurationAccumulator()30     PlaybackDurationAccumulator() {
31         mPlaybackDurationNs = 0;
32         mPreviousRenderTimeNs = 0;
33     }
34 
35     // Process a render time expressed in nanoseconds.
onFrameRendered(int64_t newRenderTimeNs)36     void onFrameRendered(int64_t newRenderTimeNs) {
37         // If we detect wrap-around or out of order frames, just ignore the duration for this
38         // and the next frame.
39         if (newRenderTimeNs < mPreviousRenderTimeNs) {
40             mPreviousRenderTimeNs = 0;
41         }
42         if (mPreviousRenderTimeNs > 0) {
43             int64_t presentationDurationNs = newRenderTimeNs - mPreviousRenderTimeNs;
44             if (presentationDurationNs < MAX_PRESENTATION_DURATION_NS) {
45                 mPlaybackDurationNs += presentationDurationNs;
46             }
47         }
48         mPreviousRenderTimeNs = newRenderTimeNs;
49     }
50 
getDurationInSeconds()51     int64_t getDurationInSeconds() {
52         return mPlaybackDurationNs / 1000 / 1000 / 1000; // Nanoseconds to seconds.
53     }
54 
55 private:
56     // The playback duration accumulated so far.
57     int64_t mPlaybackDurationNs;
58     // The previous render time used to compute the next presentation duration.
59     int64_t mPreviousRenderTimeNs;
60 };
61 
62 } // android
63 
64 #endif // PLAYBACK_DURATION_ACCUMULATOR_H_
65 
66