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java – Android: startRecording() called on an uninitialized AudioRecord when SAMPLERATE set to 44100

Posted by: admin May 14, 2020 Leave a comment

Questions:

I get an error, when I set the sampling rate to 44100 for the AudioRecord object. When it’s 22050 it works fine.

02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/AudioRecord﹕ frameCount 1024 < minFrameCount 1792

02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/AudioRecord-JNI﹕ Error creating AudioRecord instance: initialization check failed.

02-16 10:45:45.099 24021-24021/com.vlad.jackcomms E/android.media.AudioRecord﹕ Error code -20 when initializing native AudioRecord object.

02-16 10:45:45.109 24021-24021/com.vlad.jackcomms E/AndroidRuntime﹕ FATAL

EXCEPTION: main
Process: com.vlad.jackcomms, PID: 24021
java.lang.IllegalStateException: startRecording() called on an uninitialized AudioRecord.

Here’s the relevant code:

private static final int RECORDER_SAMPLERATE = 22050*2;
private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;

    recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
            RECORDER_SAMPLERATE, RECORDER_CHANNELS,
            RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);

    recorder.startRecording();
How to&Answers:

Don’t forget to ask for AUDIO_RECORD permission too

private void checkRecordPermission() {

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.RECORD_AUDIO)
            != PackageManager.PERMISSION_GRANTED) {

        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.RECORD_AUDIO},
                123);
    }

Answer:

You could check if 44100 is supported by your device.
Android does not provide an explicit method to check it but there is a work-around with AudioRecord class’ getMinBufferSize function.

public void getValidSampleRates() {
    for (int rate : new int[] {44100, 22050, 11025, 16000, 8000}) {  // add the rates you wish to check against
        int bufferSize = AudioRecord.getMinBufferSize(rate, AudioFormat.CHANNEL_CONFIGURATION_DEFAULT, AudioFormat.ENCODING_PCM_16BIT);
        if (bufferSize > 0) {
            // buffer size is valid, Sample rate supported

        }
    }
}