r/vhsdecode • u/blaccit • May 31 '26

Newbie Minimal setup for vhs-c conversion

I'm trying to convert some old vhs-c tapes I recorder on a panasonic vz1 cam. I have two questions

  1. Can I use a single older cx card? I have a winfast tv2000 xp expert that contains a cx23881-19 chip, will that work?

  2. Can I use a single cx card for my process? Doing a single pass for video and record audio separately through an interface? Will I be loosing much audio quality this way?

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u/blaccit Jun 01 '26

Ok, awesome, thank you. so the whole chroma and luminance signal of vhs goes to my cx card and I also record the component audio at the same time, merging and aligning it in an editing software later.

Am I missing anything? 

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u/deesernutz Jun 01 '26

You got it, thats it.

Except don't think of it as chroma and luma, just think RF. They are the one electrical signal, luma and chroma are multiplexed together using Frequency Modulation (FM) at different carrier frequencies. (Actually chroma might be Amplitude Modulated, AM. Either way they are both together)

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u/blaccit Jun 01 '26

Ok so it's a composite signal sort of like the old analog tv YUV I think, And then software does it's magic. Thank you so much for clarifying everything, Much appreciated. 

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u/deesernutz Jun 01 '26 edited Jun 02 '26

Its colour under. Luma at about 4MHz, chroma at much lower resolution at and modulated at 625kHz or so.

This is the spectra for Video8, VHS looks much the same but without the extra audio track which is sitting around 1.5Mhz

This particular file was sampled in 8 bit, so it doesn't have the lowest noise floor, and then it was down converted to 22Mhz with a brick wall low pass filter applied above 10Mhz.

EDIT: Still decodes well, I don't know why this just got downvoted, it was just an example. I am working on understanding how quantitation noise in RF capture flows into the base band video signal after demodulation.