JAVA：控制音频输入流的音量

Question

I use in a java code a wav file that I load into an AudioInputStream using AudioInputStream ais = AudioSystem.getAudioInputStream("file.wav")

Once I have done that, I wish to basically pick up the n amount of seconds at the end (let's say the 5 last seconds) and "fade out" the volume (FloatControl.Type.MASTER_GAIN??).

Once done I could transfert my audiostreaminput back into a wav file using: AudioSystem.write(ais, Type.WAVE, file_output);

the result is a same wav file but with the last 5 seconds fading out (volume decreasing).

Any idea on how to do this? I tried changing the ais into bytes[], or a sourcedataline... but didn't find what I wanted, as most examples are about changing volume of an audio "in-play" (I also saw things around using Clip which also seems to be dealing an audio file in-play)

Many thanks everyone

Answer 1

Start by turning the sound into a byte array. Then turn the bytes into samples: you'll need to find a tutorial specifically for this, it's a little involved in Java ( http://www.jsresources.org/ is a good resource). Samples are the direct representation of the sound wave.

To decrease the volume, multiply all the samples by something less than 1, and then save them back to a byte array. To fade out you'll need to multiply the last n samples by a decreasing function. Then write out the file with the proper WAV headers.

These are just a few pointers for a complex process, hopefully they will send you in the right direction.