While some of the requirements outlined in this section are stated as SHOULD since Android 4.3, the Compatibility Definition for a future version is planned to change these to MUST. Existing and new Android devices are STRONGLY RECOMMENDED to meet these requirements that are stated as SHOULD, or they will not be able to attain Android compatibility when upgraded to the future version.
Device implementations that declare android.hardware.microphone MUST allow capture of raw audio content with the following characteristics:
The capture for the above sample rates MUST be done without up-sampling, and any down-sampling MUST include an appropriate anti-aliasing filter.
Device implementations that declare android.hardware.microphone SHOULD allow capture of raw audio content with the following characteristics:
If capture for the above sample rates is supported, then the capture MUST be done without up-sampling at any ratio higher than 16000:22050 or 44100:48000. Any up-sampling or down-sampling MUST include an appropriate anti-aliasing filter.
The android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source MUST support capture at one of the sampling rates, 44100 and 48000.
In addition to the above recording specifications, when an application has started recording an audio stream using the android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio source:
If the platform supports noise suppression technologies tuned for speech recognition, the effect MUST be controllable from the android.media.audiofx.NoiseSuppressor API. Moreover, the UUID field for the noise suppressor’s effect descriptor MUST uniquely identify each implementation of the noise suppression technology.
The android.media.MediaRecorder.AudioSource class includes the REMOTE_SUBMIX audio source. Devices that declare android.hardware.audio.output MUST properly implement the REMOTE_SUBMIX audio source so that when an application uses the android.media.AudioRecord API to record from this audio source, it can capture a mix of all audio streams except for the following: