Getting rid of audio hum

[Gilgamesh_48 943]

First this is nothing to do with Emby at all. Emby plays exactly what is presented to it and that is good.

However I have several old, VERY old in some cases, video file that I ripped or recorded years ago. They are mostly TV shows and I lost the DVDs/VHS tapes that they originated from many years ago in a fire so I cannot rip them again. The problem is that there is a low hum in the audio for much of the file.

I would like to clean them up but I simply do not really know how.

What I am asking is if there is a way to remove the hum without too much effort and without degrading the video? I am basically lazy so please take that into account as well.

[ebr 14904]

I would imagine you could run them through a video editor like DaVinci Resolve and apply a high-pass filter to the audio track.  You'd have to play with a value that reduces the hum but doesn't make the overall track too "tinny".

Some ffmpeg wizard may also know of a way to do this with that but I'm not sure if that's possible...

[sydlexius 240]

There may be specific filters for this if it's related to 60Hz hum (this includes harmonic frequencies related to it).  This is related to having a ground loop issue, and may not necessarily be present on the source media (though you indicated you no longer have access to them).  I'd recommend looking into getting a ground loop isolator if you have more material you'd like to digitize in the future.

[Gilgamesh_48 943]

On 11/26/2022 at 4:46 PM, sydlexius said:

There may be specific filters for this if it's related to 60Hz hum (this includes harmonic frequencies related to it).  This is related to having a ground loop issue, and may not necessarily be present on the source media (though you indicated you no longer have access to them).  I'd recommend looking into getting a ground loop isolator if you have more material you'd like to digitize in the future.

It is absolutely NOT any kind of ground loop. That was about the first thing I thought of and also it was among the first things I eliminated. While I can't be sure it sounds like it is more static like. It only exists on a small subset of my library and it is not bad enough for me to go to great lengths to fix it.

I suspect I can use a narrow band filter to filter that frequency out but all my filter etc are deep in storage and I do not feel good enough to dig through storage.

I thank you and I guess I should have mentioned my EXTENSIVE electronics background in my original post.
I do have a couple of software tools available that might fix the problem but I will wait until my health gets somewhat better before experimenting further.

[speechles 1917]

Depending on the source material it might be that way on broadcast television too. They had to digitally master those from old film reels. The audio was contained on the outside strip of the reel. Just like the old cassette tape days of the 80's. You had noise reduction built into the tape players. They have noise reduction built into film projectors. But did they use noise reduction when they digitally mastered the audio onto your DVD/BluRay?

In the 80's they had to come up with ways to make the material more magnetic so the source could be read without as much hiss. So cheaper tape players could produce proper audio without the expense of noise reduction circuitry. This is when those "chrome" tapes started to appear which added more magnetivity to the tape itself rather than the player having to do all the work to help with the noise reduction.

It isn't you. It isn't your equipment. It is part of the experience hearing that hiss. Some production companies that produce DVD/BluRay are too lazy to do a proper job removing said hiss and just push it the way it was broadcast on television back in the day. Some other companies remaster the audio to produce a better product. It depends on the content and fanbase for said content. Price affects everything. Remastering adds to price. If they want a cheap product they go cheap.

Your best bet is using something like GoldWave to remove the hiss. I've used this before to raise the decibel level of some stuff and remove some frequency ranges which cause harmonics over my speakers. GoldWave offers a free trial too. You will have to extract the audio stream from the file. Then run that extracted audio stream through GoldWave. Then merge that audio stream back into your original file replacing the audio already there. It is work. But it is something you only do once and then you have better audio on your media than everybody else.

https://goldwave.com/help/mobile/EffectNoiseReduction.html

 

There are other software that do this same thing as well. Do not think you have to use the program above. Other software exists that does the same thing. Just pointing out that sometimes you have to fix the mistakes that lazy encoders make to get the quality you expect from your media.

Edited November 28, 2022 by speechles