Ambient sound in audio after editing

[G a r y]

Hello,

I recorded my voice via my Zoom H2n mic to an SD card. This is powered by batteries and not connected to my PC. Then I copied the sound to my PC and as usual, it is crystal clear. I made a screencast with Impress, recorded it and then I opened KDEnlive and paired the screencast and audio. After I rendered it, the sound quality was not as good. I chose highest quality option btw. There was an ambient noise in the background. Then I tried OpenShot, totally the same. Then I to install Lightworks, actually I did it, but after installing it, it opens and then closes immediately. But this is another issue.

So then I fired up my Windows virtual machine in Virtualbox and tried to render the video in Premiere Pro. The ambient sound was still there in my video. I just can't get rid of it. Earlier when I used Windows 8.1, it was never an issue.

So what can I do? I guess there is a driver problem because if I record my voice through a microphone connected to my PC, I hear the same ambient noise in the background. But when playing music, it is perfect. So what can I do?

[flamboyant]

can you, please, upload your files somewhere?

[G a r y]

Sure.

So the 10-10-10.m4a is not the original. I edited it in Audacity but that sound is still good.
The other two files are videos. One made with KDEnlive and one with Premiere Pro.

You can find the files in the "Linux" folder.
https://www.amazon.com/clouddrive/sh...2hDz30CeGT6vYC
You can hear that ambient noise in the background. Especially if you listen it louder.

[flamboyant]

i need the original screencast as well.

[GreyGeek]

Open either file in Audacity and click the cursor on an area of speech. Then use Ctrl+1 to zoom in ALL the way to the limit. You will see a periodic pulse which I measured to be about 0.0000129 secs. Measure it for yourself and put a filter notch on that frequency. If you analyze the spectrum and use an 8192 bucket size and Enhanced autocorrelation you'll see the FFWF's of the pulse's components.

It may be an harmonic of your 50 cps mains leaking through. I had a similar situation when at a client's location they showed me characters spontaneously and randomly being placed on an input text box. I put an oscilloscope on the NetWare cable line and say a floating 12v AC. I asked them if they had any 12 volt equipment running out in their shop, which was on the other side of the accounting office wall. They did. Lincoln 12 V welders. I checked their system and found that they were floating the center ground wire. When I grounded it to the line leading to the outside transformer ground the noise went away.

Scratch that. I was editing a 1.4Gb WAV file from the JFK files Trump released and noticed the same low level pulses in a WAV file from that release. They must be an artifact created by Audacity. In prior versions of Audacity I never saw those pulse marks.

[G a r y]

i need the original screencast as well.

You guessed that! The ambient sound was in the screencast video.
I don't know why. I used SimpleScreenRecorder and I played my voice in the background so I could record my voice and the slides in the same time. And I think it was because I used ALSA instead of PulseAudio. Not sure but I'll check this soon.

Thanks for your help. I think I would have never thought that the noise could be in the screencast!

[flamboyant]

you're welcome. please mark the thread as solved.