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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_AUDIO_AUDIO_UTIL_H_ | 5 #ifndef MEDIA_AUDIO_AUDIO_UTIL_H_ |
6 #define MEDIA_AUDIO_AUDIO_UTIL_H_ | 6 #define MEDIA_AUDIO_AUDIO_UTIL_H_ |
7 | 7 |
8 #include <string> | |
9 | |
10 #include "base/basictypes.h" | 8 #include "base/basictypes.h" |
11 #include "media/base/channel_layout.h" | 9 #include "build/build_config.h" |
12 #include "media/base/media_export.h" | 10 #include "media/base/media_export.h" |
13 | 11 |
14 namespace base { | |
15 class SharedMemory; | |
16 } | |
17 | |
18 namespace media { | 12 namespace media { |
19 class AudioBus; | |
20 | |
21 // For all audio functions 3 audio formats are supported: | |
22 // 8 bits unsigned 0 to 255. | |
23 // 16 bit signed (little endian). | |
24 // 32 bit signed (little endian) | |
25 | |
26 // AdjustVolume() does a software volume adjustment of a sample buffer. | |
27 // The samples are multiplied by the volume, which should range from | |
28 // 0.0 (mute) to 1.0 (full volume). | |
29 // Using software allows each audio and video to have its own volume without | |
30 // affecting the master volume. | |
31 // In the future the function may be used to adjust the sample format to | |
32 // simplify hardware requirements and to support a wider variety of input | |
33 // formats. | |
34 // The buffer is modified in-place to avoid memory management, as this | |
35 // function may be called in performance critical code. | |
36 MEDIA_EXPORT bool AdjustVolume(void* buf, | |
37 size_t buflen, | |
38 int channels, | |
39 int bytes_per_sample, | |
40 float volume); | |
41 | 13 |
42 // Returns user buffer size as specified on the command line or 0 if no buffer | 14 // Returns user buffer size as specified on the command line or 0 if no buffer |
43 // size has been specified. | 15 // size has been specified. |
44 MEDIA_EXPORT int GetUserBufferSize(); | 16 MEDIA_EXPORT int GetUserBufferSize(); |
45 | 17 |
46 // Computes a buffer size based on the given |sample_rate|. Must be used in | 18 // Computes a buffer size based on the given |sample_rate|. Must be used in |
47 // conjunction with AUDIO_PCM_LINEAR. | 19 // conjunction with AUDIO_PCM_LINEAR. |
48 MEDIA_EXPORT size_t GetHighLatencyOutputBufferSize(int sample_rate); | 20 MEDIA_EXPORT size_t GetHighLatencyOutputBufferSize(int sample_rate); |
49 | 21 |
50 #if defined(OS_WIN) | 22 #if defined(OS_WIN) |
51 | 23 |
52 // Returns number of buffers to be used by wave out. | 24 // Returns number of buffers to be used by wave out. |
53 MEDIA_EXPORT int NumberOfWaveOutBuffers(); | 25 MEDIA_EXPORT int NumberOfWaveOutBuffers(); |
54 | 26 |
55 #endif // defined(OS_WIN) | 27 #endif // defined(OS_WIN) |
56 | 28 |
57 } // namespace media | 29 } // namespace media |
58 | 30 |
59 #endif // MEDIA_AUDIO_AUDIO_UTIL_H_ | 31 #endif // MEDIA_AUDIO_AUDIO_UTIL_H_ |
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