About the issue of capturing sound card data in Java

[Janix520]

I want to use Java to create a global DSP on Windows, which requires capturing sound card data and filtering the sound before outputting it. Do you have any methods to implement this

[umjammer]

see https://www.baeldung.com/java-sound-api-capture-mic

        byte[] buf = new byte[1024];
        int l;
        while (audioStream.available() > 0) {
            l = audioStream.read(buf, 0, buf.length);
            // buf is PCM you can DSP here
            // then output DSP-ed buf to what you want
        }

and a DSP library https://github.com/psambit9791/jdsp

[Janix520]

This can only capture the microphone, but cannot capture the sound output from the system. I have previously studied that it requires a virtual sound card to create a loopback

[umjammer]

it cannot be done by java only.

on macos it needs an application like soundflower, blackhole.
on windows? i'm not sure, see https://groups.google.com/g/jna-users/c/Zt-gK8MKB2Q (keyword is "WASAPI loopback capture"?)
on linux, do modeprobe snd-aloop

once you created a loopback device, java would recognize it as one of line in.

[umjammer]

see also https://stackoverflow.com/a/27473859

[Janix520]

I can successfully capture system sound using the xt-audio library, but after capturing, the original sound is still exist, which means I have taken a copy of the sound and it is meaningless.

I have searched for many methods, but I will continue to search for other methods.

Thank you for your answer

[umjammer]

note:

macOS has ScreenCaptureKit