maybe we need some clarification about devices:
a) video-in-device or capture card
the SAA7130 is not the tuner, it’s the capture chip (an Analog-Digital-Converter) supposed to get a analog composite video feed from a bundled tuner (use case: TV-watch-and-maybe-record-card in the old days).
if the cardmaker put 2 bucks more of components on the pcb you could also capture from a S-Vid- or Composite-Input.
reading more about the SAA7130 it looks like if combined with a digital or mixed tuner and input in this tuner is digital the SAA7130 works in passthrough mode because no A/D-Conversion needed …
the tuner on my card is a different part (20x bigger and labelled with a brand-label) … after searching the internet it looks there are about 170+ cards based on that SAA7130 chip from different big and lesser known brands and with many different tuners … it’s the same game like 1995-1999 and the BT848/BT878 chip (which was supported by beOS) was on nearly every (cheap) tv/capture-card … most times with a Philips-tuner (at least in Europe) …
a pure video-input-card does not need a tuner, e.g. you have a old device with s-vid- or composite-output and want record/digitize old footage or just view some old stuff and save space not having a bulky CRT on the desk