1 /*
2  * Copyright (C) 2015 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_AUDIO_MONO_BLEND_H
18 #define ANDROID_AUDIO_MONO_BLEND_H
19 #include <stdint.h>
20 #include <sys/cdefs.h>
21 #include <system/audio.h>
22 
23 /** \cond */
24 __BEGIN_DECLS
25 /** \endcond */
26 
27 // for in-place conversion routines
28 
29 /**
30  * In-place mono blend using the arithmetic average of the channels in each audio frame.
31  *
32  *   \param buf          buffer of frames
33  *   \param format       one of AUDIO_FORMAT_PCM_16_BIT or AUDIO_FORMAT_PCM_FLOAT
34  *   \param channelCount number of channels per frame
35  *   \param frames       number of frames in buffer
36  *   \param limit        whether to use a limiter (experimental, currently only for stereo float)
37  *
38  * \return
39  *   none
40  *
41  */
42 
43 void mono_blend(void *buf, audio_format_t format, size_t channelCount, size_t frames,
44         bool limit = false);
45 
46 /** \cond */
47 __END_DECLS
48 /** \endcond */
49 
50 #endif // !ANDROID_AUDIO_MONO_BLEND_H
51