CODEWITHSUNDEEP
javaaudiojavasound
laurentius
laurentius

Reputation: 1145

Java Sound API: Recording and monitoring same input source

I'm trying to record from the microphone to a wav file as per this example. At the same time, I need to be able to test for input level/volume and send an alert if it's too low. I've tried what's described in this link and seems to work ok.

The issue comes when trying to record and read bytes at the same time using one TargetDataLine (bytes read for monitoring are being skipped for recording and vice-versa.

Another thing is that these are long processes (hours probably) so memory usage should be considered.

How should I proceed here? Any way to clone TargetDataLine? Can I buffer a number of bytes while writing them with AudioSystem.write()? Is there any other way to write to a .wav file without filling the system memory?

Thanks!

Upvotes: 0

Views: 369

Answers (1)

Phil Freihofner
Phil Freihofner

Reputation: 7910

If you are using a TargetDataLine for capturing audio similar to the example given in the Java Tutorials, then you have access to a byte array called "data". You can loop through this array to test the volume level before outputting it.

To do the volume testing, you will have to convert the bytes to some sort of sensible PCM data. For example, if the format is 16-bit stereo little-endian, you might take two bytes and assemble to either a signed short or a signed, normalized float, and then test.

I apologize for not looking more closely at your examples before posting my "solution".

I'm going to suggest that you extend InputStream, making a customized version that also performs the volume test. Override the 'read' method so that it obtains the byte that it returns from the code you have that tests the volume. You'll have to modify the volume-testing code to work on a per-byte basis and to pass through the required byte.

You should then be able to use this extended InputStream as an argument when you create the AudioInputStream for the output-to-wav stage.

I've used this approach to save audio successfully via two data sources: once from an array that is populated beforehand, once from a streaming audio mix passing through a "mixer" I wrote to combine audio data sources. The latter would be more like what you need to do. I haven't done it from a microphone source, though. But the same approach should work, as far as I can tell.

Upvotes: 1

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