Realtime Spectrum Plot Demo

Note: The new demo version is based on QT now. Moreover I had to use VNC to do a screen capture, thus the fps is quite low.

For demonstration purposes a realtime spectrum plot based on Jack Audio Connection Kit (JACK) and SDL1 has been created. JACK is configured to use a buffer size of 512 samples and a sample rate of 48 kHz. Everytime when JACK callback is executed with new input data, audio data is copied to input buffer of FFT. When data is copied successfully, FFT operation is triggered on DSPs. Afterwards the callback of DSP operations assigned to libdsp-x15 is executed with result data which is displayed with SDL1.

Components

• jackclient - Used for realtime audio i/o via JACK
• display - Creates window and displays amplitude spectrum

Short Demo Video

The following video is a screencast which shows the realtime spectrum plot app in action. With a function generator a sine signal is generated (left window) and connected to CTAG face2|4 audio input. The right window shows a VNC connection to BeagleBoard-X15 where the spectrum plot app is running.

References

• Source Code

Important Sources

• JACK Audio Connection Kit (JACK)
• Simple DirectMedia Layer (SDL)