Recently, I use Samsung SM-G7200 mobile phone to record speech in my Android application. However, when I use AudioFormat.CHANNEL_IN_STEREO, there is no valid speech is recorded in the left channel by AudioRecord class.
Maybe its left channel is broken down. When I use AudioFormat.CHANNEL_IN_MONO, the recorded speech is valid. Therefore, which channel will be chosen when AudioFormat.CHANNEL_IN_MONO is set for AudioRecord in Android Apps? In other words, how does Android know one channel is available and another is broken down?
I have read the Android AudioRecord source code, but I have not found the answer. Based on experience of our colleagues, if AudioFormat.CHANNEL_IN_STEREO is available, the average value of left channel and right channel can be considered as audio data in AudioFormat.CHANNEL_IN_MONO mode.