如何在Android中同时录制2个麦克风？

Question

I'm trying to record audio signals from 2 in-built microphone(bottom, top) at the same time. I can pick up bottom microphone signal using

MediaRecorder.AudioSource.MIC

and top microphone signal using

MediaRecorder.AudioSource.CAMCORDER

I can record separately but I want to record at the same time from 2 microphones. Does anyone know how to record simultaneously? I tried & or | operator but I can get only 1 channel signal.

I use Galaxy S2 device.

I will appreciate any response :) Thanks in advance.

Answer 1

You can achieve this by doing a stereo recording using the AudioRecord ( http://developer.android.com/reference/android/media/AudioRecord.html ) class. Have a look at How to access the second mic android such as Galaxy 3 .

Specifying the audio format as stereo and the audio source as the camcorder automatically selects two microphones, one for each channel, on a (compatible) two microphone device.

For example:

            audioRecorder = new AudioRecord(MediaRecorder.AudioSource.CAMCORDER,sampleRate,android.media.AudioFormat.CHANNEL_CONFIGURATION_STEREO,android.media.AudioFormat.ENCODING_PCM_16BIT,bufferSize);

will initialise a new AudioRecord class, that can record from two device microphones in stereo in PCM, 16 bit format.

For more help on recording using AudioRecord (to record .wav), have a look at: http://i-liger.com/article/android-wav-audio-recording .

Answer 2

There is a misconception that in devices with 2 microphones, both the microphones will be used when recording in the stereo mode.

In my 3 years experience of testing on tens of devices, I have found that this was never the case.

The primary mic alone is used both in mono and stereo recording in the wide range of Android devices that I have worked with - from low-cost mass models to flagships.

One reason for this is that the primary mic is of a better quality (more sensitive, less noisy, etc.) and costlier than the secondary mic.