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1 // Copyright 2014 The Chromium Authors. All rights reserved. | 1 // Copyright 2014 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef MEDIA_BASE_TIME_SOURCE_H_ | 5 #ifndef MEDIA_BASE_TIME_SOURCE_H_ |
6 #define MEDIA_BASE_TIME_SOURCE_H_ | 6 #define MEDIA_BASE_TIME_SOURCE_H_ |
7 | 7 |
8 #include "base/time/time.h" | 8 #include "base/time/time.h" |
9 #include "media/base/media_export.h" | 9 #include "media/base/media_export.h" |
10 | 10 |
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27 // Updates the current playback rate. It is expected that values from | 27 // Updates the current playback rate. It is expected that values from |
28 // CurrentMediaTime() will eventually reflect the new playback rate (e.g., the | 28 // CurrentMediaTime() will eventually reflect the new playback rate (e.g., the |
29 // media time will advance at half speed if the rate was set to 0.5f). | 29 // media time will advance at half speed if the rate was set to 0.5f). |
30 virtual void SetPlaybackRate(float playback_rate) = 0; | 30 virtual void SetPlaybackRate(float playback_rate) = 0; |
31 | 31 |
32 // Sets the media time to start ticking from. Only valid to call while the | 32 // Sets the media time to start ticking from. Only valid to call while the |
33 // time source is not ticking. | 33 // time source is not ticking. |
34 virtual void SetMediaTime(base::TimeDelta time) = 0; | 34 virtual void SetMediaTime(base::TimeDelta time) = 0; |
35 | 35 |
36 // Returns the current media time. | 36 // Returns the current media time. |
37 // | |
38 // Values returned are intended for informational purposes, such as displaying | |
39 // UI with the current minute and second count. While it is guaranteed values | |
40 // will never go backwards, the frequency at which they update may be low. | |
41 virtual base::TimeDelta CurrentMediaTime() = 0; | 37 virtual base::TimeDelta CurrentMediaTime() = 0; |
42 | |
43 // Returns the current media time for use with synchronizing video. | |
44 // | |
45 // Differences from CurrentMediaTime(): | |
46 // - Values returned update at a much higher frequency (e.g., suitable for | |
47 // playback of 60 FPS content). | |
48 // - As a result, values may go slightly backwards depending on the | |
49 // implementation (e.g., uses interpolation). | |
50 // | |
51 // TODO(scherkus): Replace with a method that returns wall clock time for a | |
52 // given media time for use with VideoFrameScheduler http://crbug.com/110814 | |
53 virtual base::TimeDelta CurrentMediaTimeForSyncingVideo() = 0; | |
54 }; | 38 }; |
55 | 39 |
56 } // namespace media | 40 } // namespace media |
57 | 41 |
58 #endif // MEDIA_BASE_TIME_SOURCE_H_ | 42 #endif // MEDIA_BASE_TIME_SOURCE_H_ |
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