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  #1  
07-27-2019, 12:46 PM
dima dima is offline
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[For the PAL system].
What is the image format of VHS recordings like ? Is it a 1.33:1 format(4:3; for TV - because it is 1.37:1 for movies) ?
In my opinion, this should probably be the image format of 1.33:1.

I'm asking because I checked from recorded VHS tapes through two different devices and how it "works well" they were captured in the resolution: 720 x 576. And so I checked and this resolution is the image format 1.25:1. Capture in image format: 768 x 576 would be an image format of 1.33:1.
The picture proper to my recordings (the entire frame created "4:3" when capturing even with very thin black stripes in the "4:3" frame - captured) is different - the older ones are 1.25:1, and the newer ones are 1.33:1 - I do not know why, since theoretically from what I remember it was used the capture equipment itself and the recording software (the resolution for 100% of my sentences was set to: 720 x 576).

Should capture the signal from VHS tapes in the format: 768 x 576, but this is not done due to the limitations of the interception equipment and the software used for this, which does not support such resolution ?

We lose some of the sides of the image recorded on the VHS cassette capture in 720 x 576 resolution, not 768 x 576 ?
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  #2  
07-27-2019, 04:03 PM
ehbowen ehbowen is offline
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What software are you using for capture? VirtualDub 1.9 certainly does support capture in 768 by 576 format, although you may have to scroll down to see that option (it's at the bottom of the menu). So that leaves your capture device as the potential limitation. Lordsmurf, last I heard, had some ATI 600 USB capture devices available for a reasonable price, and they should support PAL and give you excellent quality to boot. Note: You should still use a good full-frame TBC for best results, and I've found out the hard way that a US-spec TBC will not stretch to cover a PAL signal. Find a TBC which was designed for use with PAL video. Good luck!
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  #3  
07-27-2019, 05:33 PM
themaster1 themaster1 is online now
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ntsc vhs:
luma-333x480
chroma 40x480

pal vhs:
luma: 335x576
chroma: 40x240 (the vertical chroma resolution of PAL is limited by the PAL color delay line mechanism).

Source: http://en.wikipedia.org/wiki/VHS
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  #4  
07-27-2019, 11:17 PM
sanlyn sanlyn is offline
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Capturing PAL VHS at 720x576 or NTSC at 720x480 is considered the best size and aspect ratio compromise for most restoration processing and encoding purposes. It is the frame size for standard definition DVD, BluRay, and AVCHD, and can be encoded for 4:3 and 16:9 DAR. After deinterlacing it can be resized to square-pixel sixes for anything you want. Otherwise, if you capture at 768x576 and want to make a DVD or SD-BluRay, you'll have to resize and take a quality hit. Resizing always has a cost. It's best to use resizing methods offered by Avisynth.

PAL at 768x576 square-pixel is really an oddball size that isn't usable except for personal players. It can't be used for DVD or BluRay. If you post it on the internet it will be resized to a more standard frame for a website's players.

Lossless and/or unencoded AVi files do not store imbedded aspect ratio display data. They will display at the physical frame size and are not resized for different aspect ratios by media players. After your 720x576 AVI is encoded to something like h.264 or MPEG, you can set the display aspect ratio to whatever is appropriate.
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  #5  
07-28-2019, 02:10 AM
dima dima is offline
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Thank you for your answers, but I still have not found the answer to these questions:

1. What is the image format of VHS recordings like ? Is it a 1.33:1 format ?
2. We lose some of the sides(from left and right) of the image recorded on the VHS cassette capture in 720 x 576 resolution, not 768 x 576 ?
Does it just cause it to narrow, squeeze the image (relative to the original proportions - assuming it is 1.33:1(768 x 576)) - not cutting off any part of the image originally recorded on the VHS tape... ?
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  #6  
07-28-2019, 02:17 AM
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lordsmurf lordsmurf is offline
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VHS was 4x3.

720x576 is 5x4 storage/SAR, rectangle pixels.
Either 768x576 or 720x540 is 4x3 display/DAR, square pixels.
Nothing should ever be lost, just reshaped/squeezed from rectangle to square.

I think you already understand this, but are just unsure of yourself.

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  #7  
07-28-2019, 02:38 AM
dima dima is offline
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Since VHS was/is recorded in 4:3 image format, i.e. in the 1.33:1(768 x 576) aspect ratio.
720 x 576 is 1.25:1.
It only surprises me why the my video captured in 720 x 576 (1.25:1) presents itself (its entire frame) at 1.33:1...(recording from 2005).

1. At what resolution is it best to capture VHS (PAL) recordings via VirtualDub? 720 x 576 or 768 x 576 ? It doesn't matter to the image quality ?

2. Can VirtualDub edit a resolution of a given material from 720 x 576 to 768 x 576 and save it like this(768 x 576) ?

3. ATI AIW USB captures in 768 x 576 or only in maximum 720 x 576 resolution ?

4. What is the third number (24) shown at screen resolution, for example: 720 x 576 x 24 ? What does it define ?

I'm still not sure about different things and I'm asking...

Last edited by dima; 07-28-2019 at 02:51 AM.
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07-28-2019, 08:59 AM
ehbowen ehbowen is offline
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I need to amend my previous statement about capturing PAL in 768 x 576; I don't have much PAL equipment but I sat down and tried a capture last night. I was able to capture in 720 x 576 OK, but when I tried capturing in 768 x 576 I got the error message, "this resolution is not supported by the capture device" (I was using an ATI AIW X1800 card). So VirtualDub does support it in software, but ATI may not support it in hardware. The good news is that the 720 x 576 capture looks good...within the limitations of my equipment; my only PAL deck does not support S-Video or line TBC and I'm using a Snell & Wilcox standards converter as a sort-of frame TBC.

Here's a clip from the capture.


Attached Files
File Type: avi SongOfTheSouth-PAL.20190727.clip.avi (93.03 MB, 16 downloads)
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  #9  
07-28-2019, 10:14 AM
dima dima is offline
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Thank you for your message and information ehbowen.
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  #10  
07-28-2019, 09:46 PM
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lordsmurf lordsmurf is offline
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Quote:
Originally Posted by dima View Post
It only surprises me why the my video captured in 720 x 576 (1.25:1) presents itself (its entire frame) at 1.33:1...(recording from 2005).
I think you're still confused about DAR vs. SAR.

Capture 720x576, period, nothing more to discuss on it.

You never convert to 768x576, you never do anything at that size. DAR translates rectangular pixels to that size for playback, or 720x540, but nothing is stored that way.

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