Best practice to eliminate hiss from old VHS source

[loninappleton]

I have a newer dvd source which came from television or vhs or similar where hiss is very audible.

Is there a best practice way in Goldwave to eliminate it?

There is a hiss filter as I recall. I've owned the program for a long time but only have occasion to
work with audio periodically. The source is about 2 hours but I don't know if that is relevant.

If you can give the steps that would help as well.

[DougDbug]

Look-up Effects -> Filter -> Noise Reduction in the user manual.

The best technique is usually to copy a "noise fingerprint" (noise only) into the clipboard and then choose the "Use Clipboard" option.

If the hiss is bad there can be noise reduction artifacts and "the cure can be worse than the disease." So, it's something you have to experiment with to see if you can get good results.

You can also try a Noise Gate, which are some presets in the Compressor/Expander effect. A noise gate completely kills the sound when the level drops below a preset level (i.e. when there is only noise). But again, sometimes you can hear the background noise/sound cutting in-and-out and that can be distracting and unnatural.

I have a newer dvd source which came from television or vhs or similar where hiss is very audible.

At some point VHS Hi-Fi was introduced which was very high quality and better than anything else until the CD was introduced. VHS Hi-Fi was a 2nd audio track in addition to the regular audio track. On some machines, there may be a way to select the audio track, but I think the Hi-Fi track should play automatically if it's available and if the player supports it.

But of course, the source audio has to be "clean" and some older soundtracks or homemade soundtracks are going to sound bad on VHS, DVD, or Blu-Ray.

[loninappleton]

Can you explain more about how to tease out the noise finger print, if that's what it is?

I would be using an mkv version of the content dragged into Gw where the program finds the audio, then save that off
as .wav for further processing. Then remux it with mkvmerge. These tools are discussed in other forums and I have
a bit of experience with that.

[DewDude420]

In order for noise reduction to work properly; you have to tell it what it's working on. So a noise-print is basically a section of audio that contains nothing but noise. No voices, no music, not even any ambient sound. Ideally, it just noise, just noise. This means you have to find a section of audio in the recording that is solely the noise you want to remove.

In Goldwave, you would select a portion of audio that has nothing but your noise and copy this to your clipboard. Then in Noise Reduction, you tell it to use clipboard.

[loninappleton]

ok I'll practice on that.

I've made a .wav and am looking at the waveform to find a good spot.

[loninappleton]

I have gone through the procedure with no errors popping up.

And I may be just expecting too much. The noise reduction is supposed to reduce the hiss not make it
disappear.

I just stopped back to ask if there is a 'zeroing' process on the noise reduction box where the sample
is shown to send to clipboard? I have done nothing in there except follow your advice to save to clipboard. Then Edit > select all > save to a new .wav file.

I did an audio test of original and NR versions but could not detect much difference. The hiss is in the background. But concentrating on dialog, every little bit shows up.

[DewDude420]

First of all, you will never fully eliminate the noise without destroying the original signal. Noise reduction is a very destructive process. You have to learn the limitations of it. If you're expecting complete noise removal, you may be disappointed.

I don't know what you mean on the "zeroing" process. When you pick "Use Clipboard"; there are no other tweaks you can really apply aside from FFT, overlap, and scale...which are basic parameters of the effect.

If you're encounting "pumping" issues, where the noise is reduced during silent parts, but is just as loud during dialog; you may need to either increase the scale so the plugin amplifies the noise; or you may need a different sample of noise. But that is going to occur just by the very nature of how it works.

[loninappleton]

I asked this since in the noise reduction dialog box there is a graph of the sample with zig - zaggy elements and different colors.

Also the little box of presets is defaulted to empty so there was nothing in there as an option. For this reason I thought the sample was just copied over.

It'll probably be best to just leave it. Old recordings are old recordings.

But at least this is a technique I had not explored before.

Thanks for answering

[DewDude420]

Oh, that graph. That graph is used for the "use current spectrum" option. When using the clipboard noise; it serves zero function.

Presets box can be empty..it shouldn't make much difference other than setting FFT, overlay, and scale,

[JackA]

I have a newer dvd source which came from television or vhs or similar where hiss is very audible.

Is there a best practice way in Goldwave to eliminate it?

There is a hiss filter as I recall. I've owned the program for a long time but only have occasion to
work with audio periodically. The source is about 2 hours but I don't know if that is relevant.

If you can give the steps that would help as well.

My nonsense. Re: Analog Recordings - Tape Wear / Tape Quality.

20 Hz. say it has 10,000 magnetic particle density to reproduce sound. You lose a few, nobody will notice.
20,000 Hz. if the same density recording tape as above, we take 10,000/1000=10, now if you lose a few magnetic tape particles, there's only 7 particles left to recreate sound!

Let's take an extreme case. say you keep playing the tape over and over and a pile of particles form, that tape hiss will diminish and high frequencies will disappear, and eventually there will be silence. So, tape hiss is what you are not hearing, and odd way to put it.

I've heard too many go overboard with noise reduction, use conservatively.

Jack

[loninappleton]

@JackA

Wise advice. I've always felt the same about Dolby NR. What you don't hear is what you don't get.
In the early days using GW I was transcribing LP phono recordings. I didn't like noise reduction at all. And a close friend
taught me how to get my head straight and 'prick up my ears' to what Dolby NR actually did.

The VHS case was a background noise so I completed the job to do without any additional treatments.

This was a good discussion though. A trip down Goldwave memory lane.

[DewDude420]

Let's take an extreme case. say you keep playing the tape over and over and a pile of particles form, that tape hiss will diminish and high frequencies will disappear, and eventually there will be silence. So, tape hiss is what you are not hearing, and odd way to put it.

If your tape unit is wearing away tape particles; then there is an issue with the tape and/or your player. That shouldn't happen. It happened with *really early* units..and we're talking about back in the 50s...and with the early Amepx video recorders.

This is not an issue with modern analog tape. It shouldn't be "wearning out" if you play it on a good unit.

Even if it was.....it has nothing to do with tape hiss. Have you ever put an old R2R tape in a machine after the adhesive had gone? The heads will rip the magnetic particles right off the backing...and you won't hear it till it gums up your heads. I've done it; ruined my Akai deck. That's why people "bake" tapes.

Tape hiss is, however, directly caused by the size and number of particles on the tape; in relation to tape speed and track width. The more particles, the less hiss; the higher speed, the less hiss; the faster the speed, the less hiss; the wider the track, the less width.

Don't try to use the 8-track arguement as proof you can wear out tape. It wasn't the tape wearing out that caused problems; but the constantly moving head getting out of alignment.

You also completely left out biasing; which is an ultrasonic frequency applied to the tape in order to make it's response linear.

Now...getting on to noise reduction.

Dolby NR is a solution to a problem with bad implementation; especially on cassette tapes. Dolby works by taking a portion of the higher frequencies, dynamically compressing them, then recording them at a much louder amplitude than normal. On playback, the higher frequency band is "expanded" to it's original dynamics and the level attenuated to it's "original" level. The net effect is that you've basically pushed the higher frequencies "over" the noise; and the attenuation combined with the expansion serve to reduce the noise.

But Dolby B had an interesting way of doing this; the frequency band was not actually fixed; it would "slide" based on frequency response on the tape..so the parameters were always changing. The chip that "decodes" dolby could easily handle this; but it just had to be able to "track" the high frequencies properly.

In reality...mass-produced cassettes are high-speed dubbed...this reduces overall fidelity on the tape. The other issue is that no one's tape-heads were perfectly aligned...causing further HF roll off. So, out the gate; you've got two issues that are preventing Dolby B from working flawlessly 100% of the time. This is why most people thought of Dolby as that "treble killing button". Their decks weren't calibrated against the deck that made the tape; and therefore can't properly decode the audio. Combine that sometimes the tapes were dubbed with dolby from the master tape...adding more headaches.

This was the case of at least mass-produced cassettes. Blank tapes that you recorded at home....oh those might sound GREAT with Dolby B on them...because your playback deck is the same one that made the tape...the Dolby levels are 100% "calibrated" and good times are heard.

Dolby C basically was just back-to-back version of Dolby B....but it also used a trick of saturating the tape to overload to achieve a higher SNR. Again...sounded completely awesome on the deck that recorded it; but it was largely incompatible with every other Dolby C deck unless you aligned and calibrated Dolby to the original deck.

Dolby B was used on cassettes becuase it's undecoded sound was considered acceptable; where as Dolby C was not.

dBX was a different story. It *had* to be decoded to be listenable; it was a pretty extreme case of noise reduction. It didn't have sliding scales or changing parameters....everything was pretty much locked down. However, it was one of the best noise reduction systems ever designed for tape; and it didn't care how out of align your tape heads were and there was no dbx level calibration.

Two more things I can think of that caused tapes to be "bad". Biasing. If you overbias a tape; it sounds muddy. If you underbias a tape, it sounds bright. Most decks didn't have any bias adjustment; and the ones that did were very few (I'm not talking about Normal Type 1 vs Crome/II and Metal/IV). So most cheap cassette decks were overbiasing blank tape. The other slight possiblity is tape-head magnetization. The tape heads will form a magnetic field after many many hours of playback; and even less when recording. This residual field can partially erase a tape during playback.

Many repeated playbacks resulting in lower fidelity were probably the result of a magnetized tape dead.

That's not to mention 99% of the tape units people use are cheap. You don't hear people with Nakimichi Dragons complaining about noise and low-fidelity.

The situation is different with VHS since you have two audio paths. The first is the linear mono track. It's a small track on a very slow tape; so it's fidelity is really poor....maybe 12khz. VHS Hi-Fi was different; it was full-range audio tracks that used FM modulation recorded "under" the video signal. The FM modulation itself reduced noise; since an FM demodulator is simply looking for a carrier that's deviating in frequency and doesn't care about amplitude.