Query on crackpot scheme for recording audio with extended bandwidth

[KiM3Ce]

This may be a really stupid question but that's how we learn, right?

According to https://en.wikipedia.org/wiki/YPbPr, a component video input has:

Y: carries luma and synchronization
Pb: Blue minus luma
Pr: Red minus luma

I would like to use a DVR to record a composite FM signal, which has a bandwidth of of 53 KHz.

I don't care about the video, I just want to record the composite. I'm experimenting with FM decoders, which convert the FM composite signal to stereo audio.

It's easy to take the composite FM signal from any tuner that has an MPX output jack or oscillosope outputs; the composite is the horizontal scope signal.

I don't expect a DVR will record without sync. If I feed the Y input on the DVR from the Y output on a cable box, that should (I hope) enable recording.

If I feed composite FM to Pb or Pr, the DVR should record it. The bandwidth of a Pb or Pr video signal should be much larger than the 53 KHZ FM signal.

On a typical DVR, how is are the Pb and Pr stored? How many bits? What sampling frequency?

Yes I know I could just record the audio, but I want a stored FM composite signal so I can compare FM MPX decoders. It seems like hijacking a DVR is a lot easier than cobbling together a recorder that can record the FM Multiplex signal.

Here's more on that signal if you want it:

https://en.wikipedia.org/wiki/FM_broadcasting

Thanks is advance!