T30 Audio slow to play, followed by noise

Technical Support
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1

Hi All
We have developed a .Net Compact 3.5 application that utilizes simple audio files to play short sounds on button presses (for example beep). There seems to a short lag between the button press, and playing the audio. However, if I press a number of buttons consecutively there is no lag. Meaning if there is a gap of more then 1second (approx) between sound plays requests a lag is evident.
Additionally, there is a strange noise after they file has played, which can only be described as a hiss followed by a squelch. I have checked the WAV file itself and it is clean.
In the past, we used PXA modules and didn’t have any audio issues, but now as we are migrating to T30 modules the delay and noise is unacceptable. I have tried updating registries as suggested in the audio registry but to no avail.

I am really at a loss as to what to try next. Any help would be appreciated.
Regards
Gareth

2

Hi All,
Problem solved. There was one registry I had not tried, setting the following was the solution:

[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\nvwavedev]
"extAmpOffTimeout"= dword:-1

The amp does not timeout which means there is a low-level background hiss, but this is far more acceptable than a delay in the button sounds. Additionally, there is now no squelch (or clipping sound) before or after the sound is played.

NOTE: If updating OSDesign.reg the key/value needs to be as follows or the build will fail:

[HKEY_LOCAL_MACHINE\Drivers\BuiltIn\nvwavedev]
"extAmpOffTimeout"=dword:ffffffff

I hope this is of help to someone else.

Regards
Gareth

3

Dear @gareth
I’m glad you were able to solve the issue.

There’s one more setting which affects the delay of audio playback: The audio buffer length described in the article about Audio Driver Registry Settings.
A small buffer setting can cause buffer underruns, but the longer the buffer, the longer the initial latency when starting to play any sound.

Regards, Andy

4

Hi Andy

I did try reducing the max buffer size initially to 1000, but this didn’t seem to make much of difference for me. The timeout seems to do the job, but I might try it with the reduced buffer size and how that is as well.

Regards, Gareth