I have a problem with my DC offset

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Edmonds
Posts: 150
Joined: February 6th, 2018, 2:40 pm

Post by Edmonds »

:help: :help: :help: :help:

I am reading this as a solo, and I have had a PL PL it for me, and she says that I have a problem with my DC offset. As you may hear, there are frequent pops and crackles, but I have done the recommended DC offset fix, and yet nothing seems to help. I'm rather new to Librivox (look at my post count) and to Audacity, I was hoping some of you wizards could help out.

https://librivox.org/uploads/xx-nonproject/Help!.mp3
philchenevert
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Post by philchenevert »

Edmonds wrote: February 27th, 2018, 7:13 pm :help: :help: :help: :help:

I am reading this as a solo, and I have had a PL PL it for me, and she says that I have a problem with my DC offset. As you may hear, there are frequent pops and crackles, but I have done the recommended DC offset fix, and yet nothing seems to help. I'm rather new to Librivox (look at my post count) and to Audacity, I was hoping some of you wizards could help out.

https://librivox.org/uploads/xx-nonproject/Help!.mp3
yeah, I see you problem. But is isn't a big one in my opinion. But first you should fix the bit rate to 128kbs; right now the sample you attached is a variable 94kbs. I personally have no problem with your DC offset as shown in your recording, but others have different opinions and you should definitely talk with your PL about what they are looking for, my opinion is just my opinion. By applying normalize secdral times I got it closer to the line but not entirely zereoed. It does not seem to affect the quality of the audio at all and it sounds great to me. Good voice too! Sorry I could not help more.
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Availle
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Post by Availle »

It seems to me that there is something wrong with your equipment since the DC offset appears while you are speaking. I can see that this might be the reason why the usual "remove DC offset" is not working.

Is there a cable on your microphone? Does it move during recording - meaning: does it bump against something or other while you are recording? Eliminating this movement might help.
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GrayHouse
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Joined: October 6th, 2012, 3:27 pm

Post by GrayHouse »

I also suspect that your equipment is not working as it should. The offset and the constant clicks/pops shouldn't be there. I found the clicks quite distracting when listening on headphones.

It's always better to tackle these issues at source rather than try to fix bad audio. But if you want to fix them in Audacity, you might try the following:

The offset isn't really a dc offset - it's more like low frequency noise. You can fix it with a High Pass Filter.
In Audacity, select Effect > High Pass Filter... and use Parameters:
- Frequency: 20Hz
- Rolloff: 48dB

You can reduce the clicks using Effect > Noise Gate. Use Parameters:
- Select Function: Gate
- Apply Low Cut Filter: No
- Level Reduction: -15dB
- Gate Threshold: -32dB
- Attack/Delay: 250ms
You could use more Level Reduction - just experiment - but be careful about using too much. You need to reduce the clicks without damaging your voice recording too much.

Another method to fix the clicks/pops would be to use the De-Clicker plugin. I don't think it comes pre-installed, but you can download it from here. Copy it to the Plug-Ins folder in your main Audacity folder. Then use Effect > Add/Remove Plug-ins to enable it - you should then see it appear as an item on your Effect menu. It has quite a high processing overhead but many people here like it for removing vocal clicks (tongue clicks etc.) You may get better results than using the Noise Gate, so feel free to experiment.

As I said above, it's better to aim for a cleaner recording. If you can borrow another microphone from somewhere, you may be able to narrow down the source of the problem - I suspect your microphone isn't working as it should. Maybe you could post some details about your recording setup (mic model, laptop/PC model, operating system etc.) Someone else may have some more thoughts on the matter.

Hope that helps,
-Ian
Penumbra
Posts: 1358
Joined: May 10th, 2016, 6:16 pm

Post by Penumbra »

It might be useful to record a few minutes of dead silence to see if the problem is transient or persisting. If you can, put the mic between a couple of pillows and pick a time when there aren't any ambient sounds, no airplanes, no fans running, no neighbor with a lawn mower, etc.
The clicks remind me of a grounding or cable shielding problem.
Tom Penn
Edmonds
Posts: 150
Joined: February 6th, 2018, 2:40 pm

Post by Edmonds »

I also suspect that your equipment is not working as it should. The offset and the constant clicks/pops shouldn't be there. I found the clicks quite distracting when listening on headphones.

It's always better to tackle these issues at source rather than try to fix bad audio. But if you want to fix them in Audacity, you might try the following:

The offset isn't really a dc offset - it's more like low frequency noise. You can fix it with a High Pass Filter.
In Audacity, select Effect > High Pass Filter... and use Parameters:
- Frequency: 20Hz
- Rolloff: 48dB

You can reduce the clicks using Effect > Noise Gate. Use Parameters:
- Select Function: Gate
- Apply Low Cut Filter: No
- Level Reduction: -15dB
- Gate Threshold: -32dB
- Attack/Delay: 250ms
You could use more Level Reduction - just experiment - but be careful about using too much. You need to reduce the clicks without damaging your voice recording too much.

Another method to fix the clicks/pops would be to use the De-Clicker plugin. I don't think it comes pre-installed, but you can download it from here. Copy it to the Plug-Ins folder in your main Audacity folder. Then use Effect > Add/Remove Plug-ins to enable it - you should then see it appear as an item on your Effect menu. It has quite a high processing overhead but many people here like it for removing vocal clicks (tongue clicks etc.) You may get better results than using the Noise Gate, so feel free to experiment.

As I said above, it's better to aim for a cleaner recording. If you can borrow another microphone from somewhere, you may be able to narrow down the source of the problem - I suspect your microphone isn't working as it should. Maybe you could post some details about your recording setup (mic model, laptop/PC model, operating system etc.) Someone else may have some more thoughts on the matter.

Hope that helps,
-Ian
:help:
I am working on some of these options, thank you.
:help:
Availle wrote: February 27th, 2018, 8:33 pm It seems to me that there is something wrong with your equipment since the DC offset appears while you are speaking. I can see that this might be the reason why the usual "remove DC offset" is not working.

Is there a cable on your microphone? Does it move during recording - meaning: does it bump against something or other while you are recording? Eliminating this movement might help.
:help:
Yes, I have a corded mic, but I will personally guarantee that the cord never moves, I set the mic to one side and never touch it.
:help:
It might be useful to record a few minutes of dead silence to see if the problem is transient or persisting. If you can, put the mic between a couple of pillows and pick a time when there aren't any ambient sounds, no airplanes, no fans running, no neighbor with a lawn mower, etc.
The clicks remind me of a grounding or cable shielding problem.

:help:
There is absolutely no background noise where I record, I record in my basement, we live about 300 yards from out nearest neighbor, and there is no ventilation down there. I will do your suggestion nonetheless.
:help:
Edmonds
Posts: 150
Joined: February 6th, 2018, 2:40 pm

Post by Edmonds »

:D :D :D

Since I can't seem to figure out this clicking problem, would y'all recommend I do it over? I don't seem to have the problem on any of my other recordings because I used different software for the rest of the chapters.
Penumbra
Posts: 1358
Joined: May 10th, 2016, 6:16 pm

Post by Penumbra »

Edmonds wrote: March 1st, 2018, 10:02 am Since I can't seem to figure out this clicking problem, would y'all recommend I do it over? I don't seem to have the problem on any of my other recordings because I used different software for the rest of the chapters.
If you have a hardware/software configuration that doesn't exhibit the problems then it might be faster for you to just re-record. Eliminating the low frequency bias with a high pass filter is quick and works well, but knocking out the clicks without damaging the vocals too much will be tedious, I think. If you'd rather not re-record, then do the suggested high pass filter and the noise gate steps, give it a listen to make sure it sounds OK (an aggressive noise gate may clip the quiet parts at the ends of words), and ignore the mostly subtle clicks that coincide with your speaking. Or maybe someone can come up with some de-clicker settings that work (I couldn't).
Tom Penn
Edmonds
Posts: 150
Joined: February 6th, 2018, 2:40 pm

Post by Edmonds »

:D :D :lol: :D :lol: :D :lol: :D :D

NOTICE

I have successfully edited out all the clicks and buzzes. I used the High Pass Filter, then Click Removal (which left me with some buzzing), and then the Low Pass Filter to remove the buzzing. A little amplification and she sounds great. Thank everyone for their great suggestions in helping me to fix this problem.
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