Many good points, and I shorten the repeated thread above ....................

@Andrew

First 
FLAC is audio codec, but from what I saw ppl used it with huffyuv for
example on Windows, so main output from drivr should be uncompressed

Of course, my confusion, FLAC is "Free Lossless Audio Codec", which I never have used so far (remembered Andrea mentioned it).

Could i.e free, lossless FFV1 (or x265 lossless) be useful "LTS and crossplatform compatible codecs" to compress 4:2:2 SD and HD video output for archiving and editing?
So far I have used proprietary ProRes HQ via BM Hyperdeck Shuttle 2, but an open format is a wishible option.
(Playback S-Video via TBC and converted to DV PAL (4:2:0) has visible less colors, which also may be due to Datavideo bult-in the A/D converter in the recorder..)


1) AVerMedia CE310B
This PCIe videograbber is possibly "End Of Life - This product is no longer available to purchase"
https://www.scan.co.uk/products/avermedia-ce310b-pcie-frame-grabber-with-composite-s-video-interfacing?__cf_chl_captcha_tk__=pmd_750OsGngyr3HJ_Tm7NOj_k_LupqeA9reTqddMnXjA.0-1632945021-0-gqNtZGzNA1CjcnBszQfl

2) AVerMedia CL311-M2
This looks to be a newer, more professional and > US $300 costly PCIe video capture card that supports both analog video, full HD(MI) video and more.
Beyond Windows support, there is a Linux Driver (2.0.8) for Ubuntu 20.04/18.04/16.04, kernel 5.4.0-4.15.0, TegraOS kernel 4.4.0, Support users to complie driver by themselves.
While the first CL311-M1 included a S-Video connector on its backplane, the M2 version apply a cable dongle and supports 8 bit colors, 4:2:2 uncompressed format..
(That is, not unlike BM's (previous) Intensity Pro video grabber card)

https://professional.avermedia.com/frame-grabbers/cl311-m2/
https://www.avermedia.com/professional/download/cl311_m2#ans_part
https://www.avermedia.com/professional/faqs/cl311_m2
https://www.avermedia.com/professional/product/sdk/overview
https://www.amazon.com/AVerMedia-1080P-60FPS-Capture-CL311-M2/dp/B07B9YHWS9


@Mat and @Stefan

- I would avoid plug-in cards, you are completely dependent on the
  manufacturer's support for Linux drivers. On the other hand, USB
  grabbers usually follow standard USB audio/video rules, and almost
  always work.
-------------------
Your argument is valid for drivers in Linux. The problem with the USB 
drivers and Linux;
 - Linux supports a single endpoint per device, when the device needs two
   independent drivers this causes a problem. For example V4L + libusb with
   an ATEM.


3) AVerMedia CU511B
This full HD and SD Capture Box, 8 bit 4:2:2 with USB 3.0, could possibly be an interesting external counterpart to the CE311-M2 PCIe capture card mentioned above.
However I would expect it costs at least as much; possibly therefore my search didn't find it for sail.
According to the latest datasheet (DS_CU511B_EN_21060630.pdf, 1.5 MB), Windows and Linux driver support is included (and possibly required?) as
•Linux Services
•Support Linux kernel 2.6.14 version and later based on V4L2 & ALSA framework
•Driver customization service by request

https://www.avermedia.com/professional/news/20
https://www.avermedia.com/professional/product/cu511b/overview
https://www.avermedia.com/professional/product/cu511b/spec
https://www.avermedia.com/professional/faqs/cu511b
http://storage.avermedia.com/web_release_www/CU511B/DS_CU511B_EN_21060630.pdf


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Terje