Can audio noise be removed post capture?

[Scottymac22]

I've played this tape on multiple VCR's and this hiss noise is there on all of them but it's much louder (compared to the announcer's voice) after I capture with VirtualDub. I uploaded a sample of the capture...

[vwestlife]

What is the source? That sounds like EP speed VHS with linear audio and some of the video signal leaking into the audio, and/or a recording of an over-the-air analog TV signal with some multipath interference (ghosting).

Sometimes it was recorded poorly and that noise is "baked into" the recording. But sometimes it's caused by the VCR you're using to play it.

[Scottymac22]

JVC SRV101 through TBC and Pinnacle 510. It was a recording from an over the air broadcast back in early 90's. I played through another vcr to tv and this sound is still there but much lower than this. The attached sample after Vdub capture has a high noise to voice volume ratio so I have to turn the volume up pretty loud to hear the announcers but the noise is so much louder.

[timtape]

Hopefully the poor signal to noise ratio is not baked in to the recording as it would probably not be easy to fix in post.

Your SRV101 is SVHS capable. Unfortunately being SVHS doesnt guarantee an audio playback advantage. Sometimes the audio playback is worse than on some VHS machines.

On which VCR did it sound better? Any chance of an audio sample of that playback for comparison?

[lordsmurf]

There's also no rule that both video and audio have to be captured in the same deck.

- For some tapes, you just need to capture best image, then capture best audio.
- Re-merge in NLE. VirtualDub can also be used, but it's more tricky without a timeline.

The V101 is an excellent deck, and can be a top 10 model -- especially units I've graded as A-/A+. Mostly for video, not always for audio.

(There are ways to tweak decks for audio, pet tape, but audio realignment is so easy to screw up. Even for those of us that are careful, and know what we're doing.)

[timtape]

Some VCR's add significant extra audio noise which is not actually there on the recording. But it's not always obvious where the noise is coming from. An audio expert such as myself can determine that with special techniques, using just the one machine. But most users discover this, sometimes by accident, by playing the same tape on multiple machines, as you did. We've had previous audio examples of this uploaded by members on the forum.

On your sample there are different types of noise but as an example, here is one suspicious band of noise. I circled it in green in the spectrum display below. The noise may be on the tape or may be added by your VCR. Our problem here is that not having your tape to test ourselves we cant be sure if it's on the tape or from the VCR. You can hear it but we cant. So again if you could upload the same excerpt played on the quieter or quietest sounding machine we can at least hear what you are hearing and look at the spectral display as well. Other things may also be revealed after you upload this other capture.

As a rule it's better to capture video and audio as cleanly as possible rather than adding VCR created artefacts to the capture file and then trying to remove those same artefacts with software post capture. It's a bit like the old saying: "it's not easy to unscramble eggs."

[vwestlife]

Those high-frequency "birdies" are well above the frequency response of the recording, so you can lowpass filter it to remove them.

It's hard to see the scale of that graph, but if it's a linear EP speed recording, they fall off pretty rapidly above 5 kHz.

[timtape]

Quote:

Originally Posted by vwestlife

Those high-frequency "birdies" are well above the frequency response of the recording, so you can lowpass filter it to remove them.

It's hard to see the scale of that graph, but if it's a linear EP speed recording, they fall off pretty rapidly above 5 kHz.

Yes a judicious LPF here is a no brainer.

But assuming this is linear audio, where did those extra "birdies" come from? This is where I was hoping the OP could upload his better capture of this from another VCR. On previous threads we've heard such "birdies" which as you say couldnt have been recorded to the tape as the frequencies are too high for linear tape capture. They must be emanating from the VCR or some other source at time of capture.

Perhaps this is LP or even SP linear audio played back at less than its best. But from here, not having the OP's tape to test for ourselves we can only guess.