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1 /* | 1 /* |
2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. | 2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. |
3 * | 3 * |
4 * Use of this source code is governed by a BSD-style license | 4 * Use of this source code is governed by a BSD-style license |
5 * that can be found in the LICENSE file in the root of the source | 5 * that can be found in the LICENSE file in the root of the source |
6 * tree. An additional intellectual property rights grant can be found | 6 * tree. An additional intellectual property rights grant can be found |
7 * in the file PATENTS. All contributing project authors may | 7 * in the file PATENTS. All contributing project authors may |
8 * be found in the AUTHORS file in the root of the source tree. | 8 * be found in the AUTHORS file in the root of the source tree. |
9 */ | 9 */ |
10 | 10 |
11 #ifndef WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ | 11 #ifndef WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ |
12 #define WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ | 12 #define WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ |
13 | 13 |
14 #include <limits> | 14 #include <limits> |
15 #include <cstring> | |
15 | 16 |
16 #include "webrtc/base/scoped_ptr.h" | 17 #include "webrtc/base/scoped_ptr.h" |
17 #include "webrtc/typedefs.h" | 18 #include "webrtc/typedefs.h" |
18 | 19 |
19 namespace webrtc { | 20 namespace webrtc { |
20 | 21 |
21 typedef std::numeric_limits<int16_t> limits_int16; | 22 typedef std::numeric_limits<int16_t> limits_int16; |
22 | 23 |
23 // The conversion functions use the following naming convention: | 24 // The conversion functions use the following naming convention: |
24 // S16: int16_t [-32768, 32767] | 25 // S16: int16_t [-32768, 32767] |
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90 for (int i = 0; i < num_channels; ++i) { | 91 for (int i = 0; i < num_channels; ++i) { |
91 const T* channel = deinterleaved[i]; | 92 const T* channel = deinterleaved[i]; |
92 int interleaved_idx = i; | 93 int interleaved_idx = i; |
93 for (int j = 0; j < samples_per_channel; ++j) { | 94 for (int j = 0; j < samples_per_channel; ++j) { |
94 interleaved[interleaved_idx] = channel[j]; | 95 interleaved[interleaved_idx] = channel[j]; |
95 interleaved_idx += num_channels; | 96 interleaved_idx += num_channels; |
96 } | 97 } |
97 } | 98 } |
98 } | 99 } |
99 | 100 |
101 template <typename T, typename Intermediate> | |
102 void DownmixToMono(const T* const* input_channels, | |
103 int num_frames, | |
104 int num_channels, | |
105 T* out) { | |
106 for (int i = 0; i < num_frames; ++i) { | |
107 Intermediate value = input_channels[0][i]; | |
108 for (int j = 1; j < num_channels; ++j) { | |
109 value += input_channels[j][i]; | |
110 } | |
111 out[i] = value / num_channels; | |
112 } | |
113 } | |
114 | |
115 // Downmixes an interleaved multichannel signal to a single channel by averaging | |
116 // all channels. | |
117 template <typename T, typename Intermediate> | |
118 void DownmixInterleavedToMonoImpl(const T* interleaved, | |
119 int num_multichannel_frames, | |
120 int num_channels, | |
121 T* deinterleaved) { | |
122 assert(num_channels > 0); | |
123 assert(num_multichannel_frames > 0); | |
124 | |
125 const T* const end = interleaved + num_multichannel_frames * num_channels; | |
126 | |
127 if (num_channels == 1) { | |
128 std::memmove(deinterleaved, interleaved, | |
129 num_multichannel_frames * sizeof(*deinterleaved)); | |
130 } else if (num_channels == 2) { | |
131 // Explicitly unroll for the common stereo case. | |
132 while (interleaved < end) { | |
133 *deinterleaved++ = | |
134 (static_cast<Intermediate>(*interleaved) + *(interleaved + 1)) / 2; | |
135 interleaved += 2; | |
136 } | |
137 } else { | |
138 while (interleaved < end) { | |
139 const T* const frame_end = interleaved + num_channels; | |
140 | |
141 Intermediate value = *interleaved++; | |
142 while (interleaved < frame_end) { | |
143 value += *interleaved++; | |
144 } | |
145 | |
146 *deinterleaved++ = value / num_channels; | |
147 } | |
148 } | |
149 } | |
150 | |
151 template <typename T> | |
152 void DownmixInterleavedToMono(const T* interleaved, | |
153 int num_multichannel_frames, | |
154 int num_channels, | |
155 T* deinterleaved); | |
aluebs-webrtc
2015/07/15 21:29:17
I don't see what this declaration (with no definit
mgraczyk
2015/07/15 21:53:56
This is the template declaration for DownmixInterl
aluebs-webrtc
2015/07/16 00:20:52
Oh, you are right. Thanks for clarifying!
| |
156 | |
157 template <> | |
158 void DownmixInterleavedToMono<int16_t>(const int16_t* interleaved, | |
159 int num_multichannel_frames, | |
160 int num_channels, | |
161 int16_t* deinterleaved); | |
162 | |
100 } // namespace webrtc | 163 } // namespace webrtc |
101 | 164 |
102 #endif // WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ | 165 #endif // WEBRTC_COMMON_AUDIO_INCLUDE_AUDIO_UTIL_H_ |
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