Remove noise from audio captured from VHS

[arminio]

I have old VHS tape transferred to DVD and I need to remove heavy noise from audio track. What's the best method and tool to do this? I tried Goldwave and his equalizer (Goldwave's built-in plugin for noise reduction destroys audio too much so equalizer was a better option) where I manage to reduce noise very good - but some parts of audio track is still noisy.

Any suggestions and better solutions?

Thanks in advance.

[mammo1789]

Remember that with audio ( and probably video) filters, less is better, same goes for noise reduction to much of it and you hear aliens. The best tools for this are Izotope RX2 advance (slow and expensive suit for restoration of audio, but great noise reduction and great click and crackle module) Audition 3 or Sony soundforge 10 ( with noise reduction use mode 2 less aggressive never 0) audio editors, or you can do it with Audacity free and very very good ( it has good filters and noise reduction too)
The best result is to select the place on the track that has only noise ( noise sample) and then apply the filter on the whole file. Mind that you should never go more than 10db reduction on one pass ( it’s better to do multiple passes 10db than one in 40db) that way you should avoid artificial sound associated with audio noise reduction. You could also do normalization and decliping ( which probably occurred while you recorded the file ).
If you upload your audio file I can try to fix it for you latter
I think that the tread is intended for audio section

[arminio]

No clipping - audio had very low volume. Should I normalize it and then reduce noise or first reduce noise and then normalize?
I know about Audacity but it crashes on my PC (don't know why - I'll try portable version later) but Goldwave also has this method of reducing noise by sample but it does not do things very good (produce some audio "artefacts" and metallic noise around speech). I will try to run Audacity with more passes as you suggested because I see lot of good comment about its noise reduction.

Thanks for help!

[pandy]

Remember Audacity, Audition and similar tools works in way that they subtract spectrum of noise form useful signal - thus it is very important to create very good noise spectrum pattern that will be subtracted form spectrum of noisy signal - if there is regular frequency (hum for example) it is sometimes better to prefilter signal with hum filter (series notch filters for fundamental and harmonics of fundamental), all those rules are OK when you dealing with source coded losslessly - your case ie already lossy coded audio is difficult - noise was already affected by compression and it will be almost impossible to remove noise transparently - expect various distortions due spectral leakage between noise spectrum and signal - try to divide your audio (not physically but logically) for smaller areas, search for areas when there is no audio except noise (use spectral analysis for such areas without strong peaks) and take very frequently new noise spectrum samples close to area where you working on.

[mike20021969]

Provided you can get a good noise profile, here's a before and after example of what I did in Adobe Audition

Use headphones to hear this VHS noise removal example at it's best:

http://www.4shared.com/mp3/p1La0IEC/ITVG1989ID_NR_BEFOREAFTER_128.html

[mammo1789]

No clipping - audio had very low volume. Should I normalize it and then reduce noise or first reduce noise and then normalize?

As i remember first normalize ( it will help with the signal) than noise reduction.
Also to low signal more noise as noise/signal ratio decreases, to high input signal and clipping might occur, the right balance when recording is crucial

for smaller areas, search for areas when there is no audio except noise

Yes best part is the beginning of the tape where there is lot of empty noise only ( you can also use sample saved from other similar file to one that you are working if you don't have blank space with noise only)

but Goldwave also has this method of reducing noise by sample but it does not do things very good (produce some audio "artefacts" and metallic noise around speech)

Exactly as i sad to much and aliens are coming .
It is best way to work in multiple passes ( preferably taking noise samples from multiple regions of the tape ) that way you are reducing possibility of metallic voice and not much ( or at all) noise left.
Pandy is right its better to use hum filter in same cases, and your file has already gone to lossy format ( if you used Dolby on the dvd if pcm it maybe lossless but rare do that)so bringing it back to losless will not make the lost signal back and compression masked much of it.

You could also try with eq filter and smoothens ( simple speaking reducing frequencies that the noise is )

[arminio]

I already tried EQ and it gives fine results but I need something better - so I'll definitelly normalize first and then try Audacity with several passes.

Thanks for all tips! This was very heplpful!

[mammo1789]

I already tried EQ and it gives fine results but I need something better

The best for restoration and little more complex Izotope

[pandy]

I already tried EQ and it gives fine results but I need something better - so I'll definitelly normalize first and then try Audacity with several passes.

Thanks for all tips! This was very heplpful!

If this is normal (not HiFi) audio track then you can safely use bandpass filter for something between 40 - 80Hz and up to 12kHz - stationary head used for normal audio on VCR is not able reproduce full audio bandwidth - best is re-record audio track from video source - thus you can first adjust properly recording levels, second avoid spectral distortions due lossy audio compression, then you can easily combine video track and audio track.

Due physical limitations of tape - it is good to divide long recording for few parts (logically) and use noise spectrum pattern (profile) close to to currently active area.

For future recordings maybe this hint will be useful - record few noise patterns (profiles) - one for example for Your computer input and connection + video player - ie start Play on VCR then after few seconds press Pause on VCR, record this noise spectrum pattern as internal device (link) noise - this noise is usually not tape related and it is quite constant in time ie can be almost blindly removed from recording, second is noise from tape - good practice is record few second of silence - this one is like own tape+transport noise. Very important hint: use same power source to connect VCR and computer (or recorder) - ie use same power bar, additionally use direct wire co connect grounds of VCR and computer(recorder) to avoid situation when level difference between both grounds will flow through signal cable (usually 1- 1,5mm2 wire have lower resistance than signal cables). All those small steps should helps with many problems, also those ferrite cores that can be found on same cables can help a lot - install them on each cable (signal and power) as close as possible to connector.

To improve brightness of sound (at end of whole processing chain) You may use spectral band replication filter (eg so called "crystality" "crystalizer") - they are usually slighlty better than EQ - they not increase noises level (usually) and recording is less dull.