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1 // Copyright (c) 2009 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2009 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 // AudioRendererBase takes care of the tricky queuing work and provides simple | 5 // AudioRendererBase takes care of the tricky queuing work and provides simple |
6 // methods for subclasses to peek and poke at audio data. In addition to | 6 // methods for subclasses to peek and poke at audio data. In addition to |
7 // AudioRenderer interface methods this classes doesn't implement, subclasses | 7 // AudioRenderer interface methods this classes doesn't implement, subclasses |
8 // must also implement the following methods: | 8 // must also implement the following methods: |
9 // OnInitialized | 9 // OnInitialized |
10 // OnStop | 10 // OnStop |
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36 virtual bool Initialize(AudioDecoder* decoder); | 36 virtual bool Initialize(AudioDecoder* decoder); |
37 | 37 |
38 // AssignableBuffer<AudioRendererBase, BufferInterface> implementation. | 38 // AssignableBuffer<AudioRendererBase, BufferInterface> implementation. |
39 virtual void OnAssignment(Buffer* buffer_in); | 39 virtual void OnAssignment(Buffer* buffer_in); |
40 | 40 |
41 protected: | 41 protected: |
42 // The default maximum size of the queue. | 42 // The default maximum size of the queue. |
43 static const size_t kDefaultMaxQueueSize; | 43 static const size_t kDefaultMaxQueueSize; |
44 | 44 |
45 // Only allow a factory to create this class. | 45 // Only allow a factory to create this class. |
46 AudioRendererBase(size_t max_queue_size); | 46 explicit AudioRendererBase(size_t max_queue_size); |
47 virtual ~AudioRendererBase(); | 47 virtual ~AudioRendererBase(); |
48 | 48 |
49 // Called by Initialize(). |media_format| is the format of the AudioDecoder. | 49 // Called by Initialize(). |media_format| is the format of the AudioDecoder. |
50 // Subclasses should return true if they were able to initialize, false | 50 // Subclasses should return true if they were able to initialize, false |
51 // otherwise. | 51 // otherwise. |
52 virtual bool OnInitialize(const MediaFormat* media_format) = 0; | 52 virtual bool OnInitialize(const MediaFormat& media_format) = 0; |
53 | 53 |
54 // Called by Stop(). Subclasses should perform any necessary cleanup during | 54 // Called by Stop(). Subclasses should perform any necessary cleanup during |
55 // this time, such as stopping any running threads. | 55 // this time, such as stopping any running threads. |
56 virtual void OnStop() = 0; | 56 virtual void OnStop() = 0; |
57 | 57 |
58 // Fills the given buffer with audio data by dequeuing buffers and copying the | 58 // Fills the given buffer with audio data by dequeuing buffers and copying the |
59 // data into the |dest|. FillBuffer also takes care of updating the clock. | 59 // data into the |dest|. FillBuffer also takes care of updating the clock. |
60 // Returns the number of bytes copied into |dest|, which may be less than | 60 // Returns the number of bytes copied into |dest|, which may be less than |
61 // equal to |len|. | 61 // equal to |len|. |
62 // | 62 // |
63 // If this method is returns less bytes than |len| (including zero), it could | 63 // If this method is returns less bytes than |len| (including zero), it could |
64 // be a sign that the pipeline is stalled or unable to stream the data fast | 64 // be a sign that the pipeline is stalled or unable to stream the data fast |
65 // enough. In such scenarios, the callee should zero out unused portions | 65 // enough. In such scenarios, the callee should zero out unused portions |
66 // of their buffer to playback silence. | 66 // of their buffer to playback silence. |
67 // | 67 // |
68 // Safe to call on any thread. | 68 // Safe to call on any thread. |
69 size_t FillBuffer(uint8* dest, size_t len); | 69 size_t FillBuffer(uint8* dest, size_t len); |
70 | 70 |
71 // Helper to parse a media format and return whether we were successful | 71 // Helper to parse a media format and return whether we were successful |
72 // retrieving all the information we care about. | 72 // retrieving all the information we care about. |
73 static bool ParseMediaFormat(const MediaFormat* media_format, | 73 static bool ParseMediaFormat(const MediaFormat& media_format, |
74 int* channels_out, int* sample_rate_out, | 74 int* channels_out, int* sample_rate_out, |
75 int* sample_bits_out); | 75 int* sample_bits_out); |
76 | 76 |
77 private: | 77 private: |
78 // Audio decoder. | 78 // Audio decoder. |
79 AudioDecoder* decoder_; | 79 AudioDecoder* decoder_; |
80 | 80 |
81 // Maximum queue size, configuration parameter passed in during construction. | 81 // Maximum queue size, configuration parameter passed in during construction. |
82 size_t max_queue_size_; | 82 size_t max_queue_size_; |
83 | 83 |
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100 // | 100 // |
101 // Safe to call on any thread. | 101 // Safe to call on any thread. |
102 void ScheduleRead(); | 102 void ScheduleRead(); |
103 | 103 |
104 DISALLOW_COPY_AND_ASSIGN(AudioRendererBase); | 104 DISALLOW_COPY_AND_ASSIGN(AudioRendererBase); |
105 }; | 105 }; |
106 | 106 |
107 } // namespace media | 107 } // namespace media |
108 | 108 |
109 #endif // MEDIA_FILTERS_AUDIO_RENDERER_BASE_H_ | 109 #endif // MEDIA_FILTERS_AUDIO_RENDERER_BASE_H_ |
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