Xiaomi Redmi Note 8 64Gb+6Gb Dual LTE [62/132] Capture for voice recognition

following characteristics:

Format : Linear PCM, 16-bit

Sampling rates : 22050, 48000 Hz

Channels : Stereo

If device implementations allow AM radio and DVD quality capture of raw audio content, they:

[C-2-1] MUST capture without up-sampling at any ratio higher than 16000:22050 or

44100:48000.

[C-2-2] MUST include an appropriate anti-aliasing filter for any up-sampling or down-

sampling.

5.4.2. Capture for Voice Recognition

If device implementations declare android.hardware.microphone , they:

[C-1-1] MUST capture android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION audio

source at one of the sampling rates, 44100 and 48000.

[C-1-2] MUST, by default, disable any noise reduction audio processing when recording an

audio stream from the AudioSource.VOICE_RECOGNITION audio source.

[C-1-3] MUST, by default, disable any automatic gain control when recording an audio

stream from the AudioSource.VOICE_RECOGNITION audio source.

SHOULD record the voice recognition audio stream with approximately flat amplitude

versus frequency characteristics: specifically, ±3 dB, from 100 Hz to 4000 Hz.

SHOULD record the voice recognition audio stream with input sensitivity set such that a

90 dB sound power level (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.

SHOULD record the voice recognition audio stream so that the PCM amplitude levels

linearly track input SPL changes over at least a 30 dB range from -18 dB to +12 dB re 90

dB SPL at the microphone.

SHOULD record the voice recognition audio stream with total harmonic distortion (THD)

less than 1% for 1 kHz at 90 dB SPL input level at the microphone.

If device implementations declare android.hardware.microphone and noise suppression (reduction)

technologies tuned for speech recognition, they:

[C-2-1] MUST allow this audio effect to be controllable with the

android.media.audiofx.NoiseSuppressor API.

[C-2-2] MUST uniquely identify each noise suppression technology implementation via the

AudioEffect.Descriptor.uuid field.

5.4.3. Capture for Rerouting of Playback

The android.media.MediaRecorder.AudioSource class includes the REMOTE_SUBMIX audio source.

If device implementations declare both android.hardware.audio.output and android.hardware.microphone , they:

[C-1-1] 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

captures a mix of all audio streams except for the following:

AudioManager.STREAM_RING

AudioManager.STREAM_ALARM

AudioManager.STREAM_NOTIFICATION

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