Re: [android-developers] AudioRecord works with short but static with byte

[Jason Proctor]

knee-jerk answer: because the individual samples 
are 16 bits wide, and by reading just a byte each 
time, you're only getting half the sample.


Any idea why reading bytes from AudioRecord would cause an error while
reading shorts would not?  The sound comes through great with short
but I get only static with bytes.

Working code with short[]:

int minBufferSize = AudioRecord.getMinBufferSize(this.getSampleRate(),


this.getChannelConfiguration(),


this.getAudioEncoding());

AudioRecord recordInstance = new AudioRecord
(MediaRecorder.AudioSource.MIC,

                        this.getSampleRate(),


        this.getChannelConfiguration(),

                        this.getAudioEncoding(),

                        minBufferSize );
bufferedStreamInstance = new BufferedOutputStream(new FileOutputStream
(this.pcmFile));
DataOutputStream dataOutputStreamInstance = new DataOutputStream
(bufferedStreamInstance);

short[] tempBuffer = new short[minBufferSize ];
recordInstance.startRecording();
while (totalBytesRead < timeToRecord*sampleRate) {
        bufferRead = recordInstance.read(tempBuffer, 0, minBufferSize );

        for (int idxBuffer = 0; idxBuffer < bufferRead; ++idxBuffer) {
                dataOutputStreamInstance.writeShort(tempBuffer[idxBuffer]);
        }
}

//      Close resourcesŠ
recordInstance.stop();
bufferedStreamInstance.close();

If I just change these two lines though, I get static:

1) Change:
short[] tempBuffer = new short[minBufferSize];

To this:
byte[] tempBuffer = new byte[minBufferSize];

2) And this:
for (int idxBuffer = 0; idxBuffer < bufferRead; ++idxBuffer) {
        dataOutputStreamInstance.writeShort(tempBuffer[idxBuffer]);
}

To this:
dataOutputStreamInstance.write(tempBuffer, 0, bufferRead);

Anyone else experience this or have suggestions?



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