Any freeware solutions for audio hiss removal?

[axlish]

The low end hiss on the audio is so bad that it sets my sub off, creating some serious hum. I've looked around the site and forums but there doesn't seem to be any freeware solutions. Thanks in advance for any pointers in the right direction.

[redwudz]

Audacity. Has a lot of filters and adjustments. Freeware also.

[celtic_druid]

From recollection EAC has such an option. Just requires that you have a section where you can only hear the hiss. EAC is also free.

[mattso]

WavePad, Kristal Audio Engine & Audacity all have noise reduction features, and are free.

[mastersmurfie]

I must also suggest Audacity...can't beat freeware...

[zoobie]

wavepad comes disabled, though, with a functional version available of course for $

audacity is niceware

[mattso]

I didn't know that about WavePad. I only looked at it briefly.

Audacity however remains on my computer.

But to be honest, "noise reduction" in these freeware audio programs leave a lot to be desired (IMHO). Whereas Audition & Sound Forge excel.

But I can honestly say I've yet to find the "perfect" NR! Even Audition, with everything tweaked & optimised in the NR dialog box, can leave a very faint "warbly" tinny artifact sound, esp. noticeable in good hi-fi speakers. I guess it depends a lot on the source material too. Sometimes it is unnoticeable.

I'm looking at hardware solutions right now, to put between my VCR & DVD recorder. I just borrowed a DBX 150 rack from a mate - I've yet to test-drive it!

[Cornucopia]

dude! DON'T USE THAT BOX FOR THAT.

dbx is a Symmetrical type of noise reduction. Here's a graphical example:


You're planning on using the "Expander" portion, mainly to make the quiet parts (noise?) more quiet. This pre-supposes a couple of things--

#1 - That your parts are always on the quiet side

#2 - That you know where the mid-point is, because you don't want something quiet getting louder

#3 - That your material would sound "restored" to natural dynamics after this process.

With various VHS masters as your "storage/transmission section" source, there is no way you would satisfy any of these criteria.

Q: Did any of these VHS's get "encoded/compressed" with dbx to begin with? If not, you're using the wrong box.

Sorry to burst your bubble, but you want to go with the right tools. No need to waste the extra time spent.

FWIW, the tools in Audition/SoundForge are very, very good when used in moderation (you can even do cumulative lesser passes as well). Other tools would be ProTools NR plugins, Sonic's NoNoise, and ALL the Cedar audio restoration plugins and boxes (which are $$$$ unfortunately, but they're the best).

HTH,

Scott

[pippas]

FWIW, the tools in Audition/SoundForge are very, very good when used in moderation (you can even do cumulative lesser passes as well).

That's the secret --- don't expect too much from each pass --- gently does it, with several passes. Excellent advice!

[mattso]

Thanks for the tip! My mate wanted to sell me this dbx rack, but I s'pose I'll give it back to him. :P

Wow, I didn't think of doing cumulative NR passes with Audition. I'm going to look into that!

Learn something new every day!

[Cornucopia]

Yeah, don't want your mate to get mad at you though.

Back when dbx was in vogue ('70s-mid'80s, before the dominance of CD's and digital audio recording), you would see a good deal more mixdown reels with dbx encoding. They should have been (and usually were) clearly labelled as such. They also should have had a specific set of calibration tone(s) at the beginning, and (this is the difficult part) every time the reel was played back it would have to be adjusted for correct azimuth first, otherwise that "midpoint/pivot/fulcrum" on the scale I mentioned earlier would be off, giving wrong dynamics to the reconstructed piece. Also, the degree of compression (usually 2:1) was enough to cause noticeable "pumping" of the background noise.

Incidentally, cassettes sometimes had that feature on higher-end decks. But I would hate to listen to one of those; I would bet there wasn't 1-in-100 cassette hobbyists that actually corrected azimuth and used calibration tones...

Scott

[mattso]

The dbx unit was 1 of 4 that came with an old Otari 1/2" 8-track r-to-r my mate bought cheap at an auction. To be honest, the lack of knobs for tweaking parameters (such as "threshold", "sensitivity", whatever) made me think it was gonna be useless for what I was doing. But I'm still going to try it, when I get the time. :P

What do you think of the cheap Behringer units, such as DSP1424P or the SNR2000? My local music shop is kindly getting in a DSP1424P (without me having to slap down a deposit), so I can try it out. It has a denoiser plus exciter & stuff.

I'm not after noise "silencing", just "reduction"!?

[Cornucopia]

I'm not readily familiar with those particular units, but Behringer has been a good name. Sounds like its denoiser is either a downward expander (makes quiet quietER below a set threshold)--like a "Noise Gate", or a Dynamic Bandpass Filter (only midrange available when quiet, wider freq. range the louder it gets), or both. Would probably not be a Spectral Profile subtracting type of Broadband DSP, because that is rarely available in Realtime (and then it is $$$$). A combination of noise reducer, EQ, and Exciter with Subharmonic Synthesizer would be a pretty good deal. Read up on downloadable manuals, etc. beforehand if poss.

Good luck,

Scott