VHS conversion resolution?
 

Greetings, I have read many articles on the topic of what resolution to capture VHS tapes in, but all the information just makes my head spin.

I would like to get a definitive answer on, in digital terms, what resolution the modes of VHS and S-VHS would be in, and if PAL or NTSC will affect those resolutions. SP, LP, SLP/EP, for both VHS and S-VHS to be clear.

I just created this account to ask this question, so I apolgise if I put this thread into the wrong category or for any other fault. Thank you.

For all PAL VHS captures, regardless of the tape speed (SP, LP...), the normal resolution is 720x576, to be displayed at 4:3. Rarely, some gear will capture at 768x576, but it is uncommon.

The NTSC resolution is slightly different; an NTSC guru will advise.

SVHS? I don't know. one of the experts will, I am sure, set us straight on that.

VHS, S-VHS, SP, LP, SLP you name it, All SD analog video tape formats are captured at 720x576 for PAL/SECAM and 720x480 for NTSC, That's the native sampling rate per standard, only 704 out of 720 is actually contain the active image, So crop to 704x576 for PAL/SECAM and 704x480 for NTSC then set your aspect ratio to 4:3 during encoding and everything will work out just fine.

As noted above, capture at the stated resolutions, 720x480 for NTSC VHS and S-VHS. (BTW, that corresponds to what is used for the higher resolution DVD and miniDV formats.) The 720 pixels per line is more than adequate to preserve all the image detail in a scan line The 480 vertical pixels corresponds to the number of (NTSC) scan lines including some of the nominal over scan area so it can capture all the TV viewable information present. Scanning with a higher resolution can result in scaling artifacts and larger files that will require more PC horsepower to process later. If upscaling is really needed, do it as a last step, not while capturing.

Okay, I think I understand more now. I've seen people talk about VHS being 360x240/288, is that untrue? I've also seen people talk about S-VHS's horizontal resolution being "more than 400" but I couldn't find anything on the vertical resolution nor an exact number for the horizonal.

That was back in the day when computers' CPU and storage were limited people try to save some data, While that's true VHS can barely resolve 200 samples horizontally, the standard wasn't tailored for VHS only, there were pro formats and telecine machines that resolved more than that, Just stick to the standard and don't worry about resolution, We are at the corner of 8k resolution computing, SD resolution should not be a concern nowadays.

TV resolution is measured in lines, the number of alternating black and while lines that can be distinguished before they blur into uniform gray, sometimes referred to a the limiting resolution. For horizontal resolution it is counted as the number of lines in a space equal to the picture height.

Vertical resolution is fixed by the number of scan lines in the frame. It can be further limited by the camera head including lens, and the viewing system. For NTSC that is 486 image scan lines some of which are not displayed on a TV set (the over scan area which is legacy from the picture tube era). Modern computer displays do not normally over scan,

Horizontal resolution of analog video is limited by the bandwidth (frequency response) of the analog imaging system. For NTSC SD broadcast that is about 4.5 mHz or roughly 330 video lines. VHS and Video 8 provide about 230 video lines, and S-VHS/Hi8 closer to 400 lines. Again, this is black and white. However, color resolution is much less, a design decision to save bandwidth and retain compatibility with B&W sets (and cost) for the consumer formats, on the order of 40 lines for VHS, S-VHS, Video8 and Hi8. (The broadcast SD signal was higher.) The standards were established based on what most users could see/would accept based on readily available technologies of the time.

A traditional TV picture tube with a wide or poorly focused flying spot may do worse. The RGB color dot pitch masks used in picture tubes may limit it as will pixel pitch of the display panel for LED/LCD displays.

360x240 or (360/288 for PAL) was a sort of minimal spec for a digitizing typical home video VHS material where storage is limited such as the old video CD format.limited and the displays are small. It is also used for some security surveillance recording. There is limited reason to use it for capturing SD video these days.

All right, so here's what I understand so far.
NTSC is 720x525, with only 704x480 used for picture, and 720x656 for PAL and only 703x576 used for picture. But TV broadcasts didn't even use the full picture resolution they could've.

VHS tapes do not capture broadcasts in their full resolution nor do S-VHS tapes. No matter the recording mode it will not affect the number of lines captured by the VHS or S-VHS tape.

Is any of this false?

What I just want to get at is what the resolution of VHS and S-VHS is. I don't mean that in a rude tone, I'm just tired of not being able to find a definitive answer.

No, PAL/SECAM is 720x625 with 704x576 active image by standard, Read the previous posts again.

For capture resolution, PAL 720x576; NTSC 720x480. :congrats:

Okay, that makes sense, I understand that. But I should still rescale it to the source material when I'm done capturing, right?

Terribly sorry, I made a few typos, my mistake. I don't know where I got 656 or 703.

I don't think you can categorise analogue video as having a "source material" size, unlike digital video eg HD, UHD, 4k, all of which are defined by pixel sizes.

You can, of course, resize/rescale it if you wish after capture (and after you've deinterlaced it).

Rescale only as necessary for your final distribution method and users. Keep the original capture files in your archive as captured. You may want to work on them again later. 8Scaling will always introduce artifacts due to interpolation and truncation, not to mention and compression artifacts if you save to a lossy compressed format.

S-VHS captures the full B&W resolution (VHS does not). Neither preserve the full color resolution of a broadcast and both have a noise floor that is higher than broadcast standards assuming a good signal at the antenna or on the cable.

But what about the jargon I hear about 360x240 for VHS and ?x400? for S-VHS?

I'll be honest, mate, I only understood everything in the first paragraph, and not much in the second. I'm afraid I'm unfamiliar with what the B&W resolution of NTSC and PAL are, nor what they would be for S-VHS and VHS. I also have no idea what a noise floor is, sorry.

Put on "ignore"! :D

I agree. You can characterize the analog signal as having a number of lines, a line duration, frequency limit (bandwidth), and noise floor. One can apply sampling theory to determine a "size" (in pixels, sampling rate, and bit depth) needed to accurately represent the analog signal. The standard resolutions mentions above, plus 8-bit depth, have been accepted as industry standards for SD video. They work well for most viewers and fit readily available gear.

The recent trend to 10-bit depth, especially for HD video, is driven by improved technology and reduced computer costs. Its benefit to SD is mainly the potential for reduced processing artifacts (e.g., interpolation and truncation) between generations. 8-bit offers a dynamic range of 48 dB, 10-bit more like 60 dB. The S/N of consumer VHS/S-VHS is perhaps 43 dB (at best) roughly 7-bit equivalent).

Thank you. This is all I needed to know. Thank you so much.

Some jargon is often advertising hype
Formats like 360x240 are options that have been used, mostly in legacy applications
Not used for current VHS, etc capture.

Noise floor is the basic level of noise and hiss in a system that is always there whether or not there is a recorded signal. It comes from the electronics, the tape, the electromagnetic signals in the air around the gear, and so on. The signal to noise ratio you see in specs typically compares the desired signal level to the noise floor.

Video horizontal resolution was discussed above in post #7. By convention they are referenced to a black and white signal. B&W because that is what the eye sees best - differences in brightness (not hue or saturation) aFor NTSC SD analog video are notionally around.
240 lines for VHS/Video8
330 lines for broadcast TV signal
400 for S-VHS/Hi8
480 lines for DV/MiniDV

Because color resolution is not as important for image viewing is is lower and generally not specified in advertising.
VHS and S-VHS have the same color resolution, maybe 40 lines or so. A broadcast TV signal is significantly higher color resolution as will DV/miniDV.

In terms of vertical resolution, NTSC is always 486. But for VHS, some of those lines are head switching noise, so you might get 470 or fewer pixels of vertical resolution. Head switching noise was usually hidden in the bezel of the CRT TV so you never saw it.

Horizontal resolution depends on whether you're talking about broadcast or VHS or S-VHS, and chroma or luma.

NTSC VHS has 240 (TVL) lines of horizontal luma resolution. Take 240 lines, multiply by 4/3 (the aspect ratio of a standard definition TV), and the result is 320 pixels of horizontal luma resolution. So VHS is 320x480.

But in order to capture all of that information, the Nyquist theorem says you should sample at 2x, so that comes to 640x480.

Chroma resolution is significantly less than luma on VHS so we'll ignore it here.

NTSC S-VHS has 420 TVL lines of luma resolution, which comes to about 560 pixels across. So, 560x486, or capture at 1120x486 if you can.

There is no capture device that can sample at 1120, 720 is the standard, you are just making him more confused than he ever was.