Modifying in-call voice playback in Android custom ROM

Question

I would like to modify Android OS (official image from AOSP) to add preprocessing to a normal phone call playback sound.

I\'ve already achieved this filtering for app aud

Answer 1

There are several possible issues that come to my mind. The blank buffer might indicate that you have the wrong source selected. Also since according to https://developer.android.com/reference/android/media/AudioRecord.html#AudioRecord(int,%20int,%20int,%20int,%20int) you might not always get an exception even if something's wrong with the configuration, you might want to confirm whether your object has been initialized properly. If all else fails, you could also do an "mRecord.setPreferredDevice(AudioDeviceInfo.TYPE_BUILTIN_EARPIECE);" to route the phone's built-in earpiece directly to the input of your recorder. Yeah, it's kinda dirty and hacky, but perhaps suits the purpose.

The other thing what was puzzling me that instead of using the builder class you've tried to configure the object directly via its constructor. Is there a specific reason why you don't want to use AudioRecord.Builder (there's even a nice example at https://developer.android.com/reference/android/media/AudioRecord.Builder.html ) instead?