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1 // Copyright 2016 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef PushPullFIFO_h | |
6 #define PushPullFIFO_h | |
7 | |
8 #include "platform/audio/AudioBus.h" | |
9 #include "public/platform/WebCommon.h" | |
10 #include "wtf/Allocator.h" | |
11 | |
12 namespace blink { | |
13 | |
14 // PushPullFIFO class is an intermediate audio sample storage between | |
15 // Blink-WebAudio and the renderer. The renderer's hardware callback buffer size | |
16 // varies on the platform, but the WebAudio always operates by 128 frames of | |
17 // render quantum; thus FIFO is needed. | |
18 class BLINK_PLATFORM_EXPORT PushPullFIFO { | |
19 USING_FAST_MALLOC(PushPullFIFO); | |
20 WTF_MAKE_NONCOPYABLE(PushPullFIFO); | |
21 | |
22 public: | |
23 PushPullFIFO(unsigned numberOfChannels, size_t fifoLength); | |
24 ~PushPullFIFO(); | |
25 | |
26 // Pushing audio data is done by the WebAudio render-backing thread. The | |
o1ka
2017/01/24 11:09:02
Do you plan to first finalize all the index calcul
hongchan
2017/01/26 22:33:18
Yes. That's the plan.
The FIFO in this CL should
| |
27 // priority of this thread is lower than the actual audio device thread, | |
28 // thus the thread can be blocked when the audio device thread is pulling | |
29 // data from the FIFO. | |
30 void push(const AudioBus* inputBus); | |
31 | |
32 // Pulling audio data is done by the audio device thread. In the case of | |
33 // underflow, the rest will be filled up with zeros (thus glitches). Pulling | |
34 // an empty FIFO is a valid operation, and the consumer will get a block of | |
35 // silence. | |
36 void pull(AudioBus* outputBus, size_t framesRequested); | |
37 | |
38 int framesAvailable() const { return m_framesAvailable; } | |
39 int length() const { return m_fifoLength; } | |
40 unsigned numberOfChannels() const { return m_fifoBus->numberOfChannels(); } | |
41 AudioBus* bus() { return m_fifoBus.get(); } | |
42 | |
43 private: | |
44 RefPtr<AudioBus> m_fifoBus; | |
45 | |
46 // The size of the FIFO. | |
47 const int m_fifoLength; | |
o1ka
2017/01/24 11:09:02
You can use "= 0" initialization here.
hongchan
2017/01/26 22:33:18
Done.
| |
48 | |
49 // The number of frames in the FIFO actually available for pulling. | |
50 int m_framesAvailable; | |
51 | |
52 int m_indexRead; | |
53 int m_indexWrite; | |
54 | |
55 unsigned m_overflowCount; | |
o1ka
2017/01/24 11:09:02
We should not use a mix of size_t, int and unsigne
hongchan
2017/01/26 22:33:18
This is a great resource. Thanks and we will follo
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56 unsigned m_underflowCount; | |
57 }; | |
58 | |
59 } // namespace blink | |
60 | |
61 #endif // PushPullFIFO_h | |
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