Noise of analog audio output when playing back movies

If you connect an amplifier board to the analog audio output of Apalis T30 + Ixora and play a movie, you will hear noise at the beginning or the end of the movie.

I do not know how to express the sound of noise, so I attach the recorded file.
I think that you hear the noise sound between playing / stopping the movie.

Is there a way to deal with something?

link text


Could you please try to disable audio codec power down as described here. The issue would be powering down and up audio codec would raise this noise issue.

Thank you for your response.

I set the registry value of “PowerDownTimeout” by referring to the explanation.
If we set the value “3000”, I imagined that the noise would sound after 3000 ms, but it did not change from the setting before.
The value “-1” did not know how to set it to DWORD.


Please set 0xFFFFFFFF is equal to -1. Did you do Save registry and Reboot after setting the registry?

Thank you for your quick response.

Yes, I restarted after “Save Reg”.
Even if you set the value to “-1” by the method taught, the noise will sound.
It seems to me that this registry setting value does not indicate the effect.

I said that noise when playing movies, but similar noise also sounds after sound effects when setting values go up and down on the volume setting screen.

I think that there is no problem because the OS uses v2.1 Release.
I am experimenting with a custom built OS, so I’d like to try it with the default OS once.

Please tell me if there is anything else to check.

Could you please try to connect low-pass filter between head-phone output and your amplifier. Audio output has a noticeable amount of high frequency signals (MHz range) leaking from digital circuits. And some amplifiers can generate an audio noise from that (intermodulation effects etc)