Den 10.02.2023 04:03, skrev Andrew Randrianasulu:

пт, 10 февр. 2023 г., 04:37 Terje J. Hanssen via Cin <cin@lists.cinelerra-gg.org>:

We have some threads this month discussing the performance of UVC HDMI-USB3 Vide Capture stics/dongles or devices.
If technical specs are available, sadly often deficient, they may manage 422 chroma subsampling, but limited to 8-bit "Deep color" (4KVC00) or "YUY2" (ms2130)

1. To repeate the illustrative article 8-Bit vs 10-Bit Video Color Explained (millions/banding vs billion shades):
https://fujifilm-x.com/en-us/series/the-filmmakers-handbook/8-bit-or-10-bit-video-color-explained/


2. In a couple of learn.microsoft articles, 10- and 16-bit YUV Video Formats are recommended for capturing, processing, and displaying video, while 8-bit YUV color formats that are recommended for video rendering. To extract and learn the most relevant YUV formats in this context from the table
https://learn.microsoft.com/en-us/windows/win32/medfound/10-bit-and-16-bit-yuv-video-formats#preferred-yuv-formats

YUY2     4:2:2     Packed     8 bits pr channel
Y210     4:2:2     Packed     10
NV12     4:2:0     Planar     8
P010     4:2:0     Planar     10

3. So I found an interesting discussion on the Digital Photography Review forum:
Cheapest (and decent) way to record 10 bits HDMI on Windows?
https://www.dpreview.com/forums/thread/4562209

Extract here an interesting section from the first reply of Mar 19, 2021:

It almost looks like 10-bit may not be part of the UVC specs unless the device does hardware H.264 or HEVC decoding, there are no 10-bit color formats that appear in https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/media/usb/uvc/uvcvideo.h?h=v5.11.7 such as p010, and I would expect that if the UVC spec supported p010 video it would have appeared in the Linux kernel by now.

Isn't such question more for Maintainer?

"USB VIDEO CLASS

M:	Laurent Pinchart <laurent.pinchart@ideasonboard.com>
L:	linux-media@vger.kernel.org
S:	Maintained
W:	http://www.ideasonboard.org/uvc/
T:	git git://linuxtv.org/media_tree.git
F:	drivers/media/usb/uvc/
F:	include/uapi/linux/uvcvideo.h

"

from https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/MAINTAINERS

I looked at (hopefully) uvc spec, but mostly for interlace info

https://www.spinelelectronics.com/pdf/UVC%25201.5%2520Class%2520specification.pdf

I'll look for guid info some more..

If someone can confirm this is the case also today, we don't need to search for cheap or inexpensive HDMI-USB3 Video capture stick/dongles with 10-bit 422 output support.

What I meant to say is that (my thought ) 8-bit YUY2 output support seems to be the current limit of HDMI-USB3 Video Capture sticks like in the new ms2130.
I saw that the (previous) USB2 model that still was announced in parallell didn't support YUY2. But I expect this is just a question of time as the chip technology evolves - so maybe the next model and UVC then get 10-bit support(?)

Down In the same thread also some high-priced UVC compliant devices are mentioned, but they tend to support 10-bit on HDMI input and so downscale it to 8-bit on USB3 output.

Apparently hacked Cx driver can output 16 bits as ADC, but then we have question of feeding it with good enough signal (vhs-decode just vampires into VCR guts.)

Is any real external vhs (ish) sources worth 10 bits path?

There have been discussions about that. VHS/Video8 is low-end composite video, while S-Video (2) and Component Video (3) are better. But cheap ADC to HDMI adapters, sadly also often with missing technical specs, most probably at best output 8-bit(?) At least here 8-bit YUY2 ms2130 may fit well.
Digital cameras with direct HDMI output on the other hand may utilize 10-bit.

As a generic reference, I compare this with "The Digitization of VHS Videotapes – Technical Bulletin 31

Digitization Set-up Two with an external capture device
https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/technical-bulletins/digitization-vhs-video-tapes.html#a8b
while Set-up _Three is Digitization with an internal (PCIe) capture card
https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/technical-bulletins/digitization-vhs-video-tapes.html#a8c

The Digitization procedure/Video compressor section discuss 10-bit vs 8-bit

https://www.canada.ca/en/conservation-institute/services/conservation-preservation-publications/technical-bulletins/digitization-vhs-video-tapes.html#a8c3

Using 10-bit is advocated by many, although several institutions also use 8-bit (see Appendix B). It is debatable whether 10-bit is required for VHS video but some believe that because of VHS’s shortcomings in the area of resolution, luminance and colour range, capturing the finer details becomes more important.Footnote 29 It is believed that capturing at higher quality will ultimately produce a better result if significant manipulation occurs, such as editing of files, and a better result if future compression of the file is necessary.

https://github.com/happycube/cxadc-linux3

===

cxadc is an alternative Linux driver for the Conexant CX2388x series of video decoder/encoder chips used on many PCI TV tuner and capture cards.

Note! cx23885 and cx23888 are incompatible chips.

The new driver configures the CX2388x to capture in its raw output mode in 8-bit or 16-bit unsigned samples from the video input ports, allowing these cards to be used as a low-cost 28-54Mhz 10bit ADC for SDR and similar applications.

====

vhs-decode wiki has some ffmpeg command encoding raw captures  into prores 10bit file

https://github.com/oyvindln/vhs-decode

Very interesting reading. I admit I have never heard about "vhs-decode" before and do not yet have an overview of what it includes.

===

VHS-Decode produces two timebase corrected 16-bit GREY16 headerless files separated into chroma/luma composite video signals in the .tbc format alongside .json and .log files, usable with the LD-Decode family of tools ld-analyse, ld-process-vbi, ld-process-vits and ld-dropout-correct.

The gen chroma scrips will use decoded .tbc files and generate standard video files by default a lossless, interlaced top field first and high-bitrate (roughly 70-100 Mb/s) FFV1 codec video which, which although ideal for archival and further processing.

For editing due to lack of support of FFV1 and sharing online without de-interlacing is not supported properly, as such the two commands are provided below to make suitable files for this use.

Both commands will automatically use the last file generated as the input.

For editors this transcodes an FFV1/V210 output to a "near complient" interlaced ProRes HQ file:

ffmpeg -hide_banner -i "$1.mkv" -vf setfield=tff -flags +ilme+ildct -c:v prores -profile:v 3 -vendor apl0 -bits_per_mb 8000 -quant_mat hq -mbs_per_slice 8 -pixel_format yuv422p10lep -color_range tv -color_primaries bt709 -color_trc bt709 -colorspace bt709 -c:a s24le -vf setdar=4/3,setfield=tff "$1_ProResHQ.mov"

For basic online sharing you can use this command to convert the FFV1 output to a de-interlaced lossy upscaled MP4:

ffmpeg -hide_banner -i "$1.mkv" -vf scale=in_color_matrix=bt601:out_color_matrix=bt709:1440x1080,bwdif=1:0:0 -c:v libx264 -preset veryslow -b:v 15M -maxrate 15M -bufsize 8M -pixel_format yuv420p -color_primaries bt709 -color_trc bt709 -colorspace bt709 -aspect 4:3 -c:a libopus -b:a 192k -strict -2 -movflags +faststart -y "$1_1440x1080_lossy.mp4"

====

Maaay be we still can use pci-e capture card with normal inputs, just process raw captures to see if there any difference between 8 and 10 bit?

I think I don't mess with internal proprietary PCIe capture cards anymore. I had once a Pinnacle DV500/DVD system for Windows 98 (or was it 95).

 

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