High Latency with ASIO driver (Behringer UCA222, Audio System Toolbox)

I am trying to use the Audio System Toolbox with ASIO driver for a low latency audio processing. I’m using a Behringer UCA222 Stereo-Input Stereo-Output USB-Soundcard and ASIO4All driver. For testing the latency of the System connected the Output and the Input Ports of the soundcard in a ring and I created a small Simulink modell, which outputs a Sine Wave of 1000 Hz. I get a smaller latency with the ASIO driver than with the DirectSound-Driver, however the latency is with about 190 msec much to high.

Similar research was done by Marc Corless and Arvind Ananthan (two mathworks engineers) in “PC-Based Prototyping of Audio Apllications using Model-Based-Design”. They got latencys of only 16.375 msec at 48 kHz and a Buffer Size of 128 Samples.

The examples in the picture are generated using 48 kHz and a Buffer of 1024 Samples.

Maybe anyone can help and find a reason why the latency of my system is that high.

Answer 1

[Puneet Rana]

What is the frame size of the input that goes into your Audio Device Writer block? What is the SamplesPerFrame used in Audio Device Reader block? What are the buffer size settings in the ASIO4ALL panel? You need to make sure that all three of them match in order to have optimal latency.

[pSchi]

Hello Puneet Rana,

Thank you for your answer.

The buffer size of the input is 128 Samples. The SamplesPerFrame in the Audio Device Reader block is 128 and the buffer size in the ASIO4ALL panel is 128 samples as well. However I still get this high latency.

In the appendix of this comment I have put a Screenshot of the ASIO4ALL panel. I'm sorry, but I'm not able to post the model since it is not possible to upload .slx files here.

[Puneet Rana]

Can you retry the experiment with the Sine Wave block from DSP System Toolbox dspsrcs4 library for the input signal to Audio Device Writer block? Set the SamplesPerFrame parameter of the Sine Wave block to 128 to match your system.