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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 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_CLOCK_H_ | 5 #ifndef MEDIA_BASE_CLOCK_H_ |
6 #define MEDIA_BASE_CLOCK_H_ | 6 #define MEDIA_BASE_CLOCK_H_ |
7 | 7 |
8 #include "base/basictypes.h" | 8 #include "base/basictypes.h" |
9 #include "base/time.h" | 9 #include "base/time.h" |
10 #include "media/base/media_export.h" | 10 #include "media/base/media_export.h" |
11 | 11 |
| 12 namespace base { |
| 13 class Clock; |
| 14 } // namespace base |
| 15 |
12 namespace media { | 16 namespace media { |
13 | 17 |
14 // A clock represents a single source of time to allow audio and video streams | 18 // A clock represents a single source of time to allow audio and video streams |
15 // to synchronize with each other. Clock essentially tracks the media time with | 19 // to synchronize with each other. Clock essentially tracks the media time with |
16 // respect to some other source of time, whether that may be the system clock or | 20 // respect to some other source of time, whether that may be the system clock or |
17 // updates via SetTime(). Clock uses linear interpolation to calculate the | 21 // updates via SetTime(). Clock uses linear interpolation to calculate the |
18 // current media time since the last time SetTime() was called. | 22 // current media time since the last time SetTime() was called. |
19 // | 23 // |
20 // Clocks start off paused with a playback rate of 1.0f and a media time of 0. | 24 // Clocks start off paused with a playback rate of 1.0f and a media time of 0. |
21 // | 25 // |
22 // Clock is not thread-safe and must be externally locked. | 26 // Clock is not thread-safe and must be externally locked. |
23 // | 27 // |
24 // TODO(scherkus): Clock will some day be responsible for executing callbacks | 28 // TODO(scherkus): Clock will some day be responsible for executing callbacks |
25 // given a media time. This will be used primarily by video renderers. For now | 29 // given a media time. This will be used primarily by video renderers. For now |
26 // we'll keep using a poll-and-sleep solution. | 30 // we'll keep using a poll-and-sleep solution. |
27 class MEDIA_EXPORT Clock { | 31 class MEDIA_EXPORT Clock { |
28 public: | 32 public: |
29 // Type for a static function pointer that acts as a time source. | 33 explicit Clock(base::Clock* clock); |
30 typedef base::Time(TimeProvider)(); | |
31 | |
32 explicit Clock(TimeProvider* time_provider); | |
33 ~Clock(); | 34 ~Clock(); |
34 | 35 |
35 // Returns true if the clock is running. | 36 // Returns true if the clock is running. |
36 bool IsPlaying() const; | 37 bool IsPlaying() const; |
37 | 38 |
38 // Starts the clock and returns the current media time, which will increase | 39 // Starts the clock and returns the current media time, which will increase |
39 // with respect to the current playback rate. | 40 // with respect to the current playback rate. |
40 base::TimeDelta Play(); | 41 base::TimeDelta Play(); |
41 | 42 |
42 // Stops the clock and returns the current media time, which will remain | 43 // Stops the clock and returns the current media time, which will remain |
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84 void UpdateReferencePoints(base::TimeDelta current_time); | 85 void UpdateReferencePoints(base::TimeDelta current_time); |
85 | 86 |
86 // Returns the time elapsed based on the current reference points, ignoring | 87 // Returns the time elapsed based on the current reference points, ignoring |
87 // the |max_time_| cap. | 88 // the |max_time_| cap. |
88 base::TimeDelta EstimatedElapsedTime(); | 89 base::TimeDelta EstimatedElapsedTime(); |
89 | 90 |
90 // Returns the current media time treating the given time as the latest | 91 // Returns the current media time treating the given time as the latest |
91 // value as returned by |time_provider_|. | 92 // value as returned by |time_provider_|. |
92 base::TimeDelta ElapsedViaProvidedTime(const base::Time& time) const; | 93 base::TimeDelta ElapsedViaProvidedTime(const base::Time& time) const; |
93 | 94 |
94 base::Time GetTimeFromProvider() const; | |
95 | |
96 base::TimeDelta ClampToValidTimeRange(base::TimeDelta time) const; | 95 base::TimeDelta ClampToValidTimeRange(base::TimeDelta time) const; |
97 | 96 |
98 // Function returning current time in base::Time units. | 97 base::Clock* const clock_; |
99 TimeProvider* time_provider_; | |
100 | 98 |
101 // Whether the clock is running. | 99 // Whether the clock is running. |
102 bool playing_; | 100 bool playing_; |
103 | 101 |
104 // Whether the clock is stalled because it has reached the |max_time_| | 102 // Whether the clock is stalled because it has reached the |max_time_| |
105 // allowed. | 103 // allowed. |
106 bool underflow_; | 104 bool underflow_; |
107 | 105 |
108 // The system clock time when this clock last starting playing or had its | 106 // The system clock time when this clock last starting playing or had its |
109 // time set via SetTime(). | 107 // time set via SetTime(). |
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121 | 119 |
122 // Duration of the media. | 120 // Duration of the media. |
123 base::TimeDelta duration_; | 121 base::TimeDelta duration_; |
124 | 122 |
125 DISALLOW_COPY_AND_ASSIGN(Clock); | 123 DISALLOW_COPY_AND_ASSIGN(Clock); |
126 }; | 124 }; |
127 | 125 |
128 } // namespace media | 126 } // namespace media |
129 | 127 |
130 #endif // MEDIA_BASE_CLOCK_H_ | 128 #endif // MEDIA_BASE_CLOCK_H_ |
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