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  #21  
08-03-2020, 07:51 AM
Okiba Okiba is offline
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Thank you (as always) for confirming it lordsmurf :-)
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  #22  
01-31-2021, 06:03 PM
thefrog1394 thefrog1394 is offline
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In the year 2021 when one will almost certainly never be burning any of these files to a DVD, is there any good reason not to just crop and eliminate the black borders? Overscan is a thing of the past. YouTube, etc will happily display video of any resolution including something weird like 636x476, no?

Also, and this might be a silly question that I can easily answer myself, but when capturing at 720x480 on my 600 USB capture device, am I capturing an additional 40 pixels on each side of the screen of width or am I now dealing with non-square pixels?
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  #23  
01-31-2021, 06:19 PM
robjv1 robjv1 is offline
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Quote:
Originally Posted by thefrog1394 View Post
In the year 2021 when one will almost certainly never be burning any of these files to a DVD, is there any good reason not to just crop and eliminate the black borders? Overscan is a thing of the past. YouTube, etc will happily display video of any resolution including something weird like 636x476, no?

Also, and this might be a silly question that I can easily answer myself, but when capturing at 720x480 on my 600 USB capture device, am I capturing an additional 40 pixels on each side of the screen of width or am I now dealing with non-square pixels?
I think you still want to just mask out the overscan for the broadest compatibility with devices and to maintain the interlacing if you don't need to use filters that require deinterlacing. I believe you can crop as long as you do it in multiples of four and still maintain the interlacing but why potentially mess with that and create a wonky sized video that some device might totally misread? Standards are there for a reason.
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  #24  
01-31-2021, 06:22 PM
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Quote:
Originally Posted by thefrog1394 View Post
In the year 2021 when one will almost certainly never be burning any of these files to a DVD, is there any good reason not to just crop and eliminate the black borders?
YouTube, etc will happily display video of any resolution including something weird like 636x476, no?
You're not understanding video. I shall educate...

For starters, Youtube butchers video. More often than not, Youtube will rape/molest your video as it sees fit. Quality is not even secondary, but shoved way a down a priority list. Youtube should never be your yardstick to quality, or anything else. Youtube is about uploading compressed video for $$$ (sometimes shared with you, sometimes not), the end.

What I focus on is ingested video, pre-delivery. Not Youtube, not optical (DVD-Video, BDAV/BDMV).

- When you resize vertically, you screw up interlace.
- Almost all video software and players require specs, not random sizes. Resizing to spec can alter the aspect ratio, and even small upsizing can screw up in-image quality (sharpness, geometry, etc).

I have never understood the OCD/ADD insanity of avoiding evil "black bars". It's extremely stupid to stretch 4x3 to 16x9, or to insist on cropping off <5% black borders that are there to retain image quality/integrity. You're supposed to enjoy the content, not flip out on areas when content is not. (I will say that postage stamping is bad video work.)

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Overscan is a thing of the past.
Not true. HD broadcasts, and sometimes even HD releases, have overscan data.

Quote:
Also, and this might be a silly question that I can easily answer myself, but when capturing at 720x480 on my 600 USB capture device, am I capturing an additional 40 pixels on each side of the screen of width or am I now dealing with non-square pixels?
720x480 is not active image. The active is 704x480 in 4:3 AR (and coming from an analog tape, has overscan that includes head-switching, CC, etc). So you'd crop 720 to 704, then resize 704 to 640. Matte the overscan, watch/upload/whatever. If you start to crop pixels, quality will only degrade.

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  #25  
01-31-2021, 07:49 PM
latreche34 latreche34 is offline
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Yep, 704x480 (704x576 PAL/SECAM) is the least resolution you can crop to without screwing the aspect ratio or the validity of the file, If 16/9 is a must you can add frosty borders on the left and right sides.

Most consumer video tapes will leave some black borders even after cropping to 704 but some do eliminate them completely or take some of the active area with it, depends on the origin of the tape, But the vertical 480 leaves a big chunk of head switch on the bottom and sometimes a black strip on the top especially 8mm/Hi8 tapes.

In my entire time since I started this hobby I came across one and only one VHS tape that doesn't have the head switch in the active video area at the bottom and the horizontal active area is exactly 704. It is a home recorded tape from a broadcast TV that picked up for free in a lot of tapes, I wish I know what VCR model recorded it because this VCR has to be freaking special, possibly a pro deck, though I've seen pro decks do produce head switch noise in the active video area.

Here is a sample from a lossless file for that tape (no aspect ratio set yet), Anyone who thinks I cropped this and resized it to fake it I can send you the actual video tape.


Attached Files
File Type: avi fullh.avi (74.17 MB, 22 downloads)
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  #26  
01-31-2021, 08:25 PM
thefrog1394 thefrog1394 is offline
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Quote:
Originally Posted by lordsmurf View Post
You're not understanding video. I shall educate...
720x480 is not active image. The active is 704x480 in 4:3 AR (and coming from an analog tape, has overscan that includes head-switching, CC, etc). So you'd crop 720 to 704, then resize 704 to 640. Matte the overscan, watch/upload/whatever. If you start to crop pixels, quality will only degrade.
Cropping degrades quality? How so?

And resizing 704->640. Would this not result in quality loss? Stuffing 704 pixels into 640. Intuitively it seems like it would be better to simply capture with square pixels (640x480) from the get-go.
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  #27  
01-31-2021, 08:50 PM
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No, you're still not seeing it...

Quote:
Originally Posted by thefrog1394 View Post
Cropping degrades quality? How so?
When you "crop" to a spec (specific allowed sizes), you must upsize/downsize. If you start with a 720x480 capture, and lop of 10 pixels from each size, then two things happen: (1) the aspect ratio is screwed up if disallowed from viewing 1:1, which is common even with the most modern players, (2) quality is lost, especially by adding aliasing and a loss of sharpness, by upsizing the now-700x460 back to 720x480. And then interlace is also screw up if interlaced, the video becomes an unviewable mess.

You cannot just arbitrarily crop to random sizes.

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And resizing 704->640. Would this not result in quality loss?
No. It's horizontal. And VHS is arguably not even 352x480, much less 640 or 704.

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Stuffing 704 pixels into 640.
This statement makes no sense. Nothing is "stuffed".

Quote:
Intuitively it seems like it would be better to simply capture with square pixels (640x480) from the get-go.
The problem here is the way capture cards ingest (usually due to drivers). The ATI AIW cards, for example, were intelligent about active pixels and aspect. But your average capture card is pretty stupid, if not capturing 720x480. Most cards are dumb about any other size beyond 720x480, as that's all the chip or driver was optimized for. If you attempt other resolutions, odd things can happen, mostly AR/sharpness/aliasing issues.

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  #28  
01-31-2021, 09:47 PM
thefrog1394 thefrog1394 is offline
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Quote:
Originally Posted by lordsmurf View Post
No, you're still not seeing it...
When you "crop" to a spec (specific allowed sizes), you must upsize/downsize. If you start with a 720x480 capture, and lop of 10 pixels from each size, then two things happen: (1) the aspect ratio is screwed up if disallowed from viewing 1:1, which is common even with the most modern players, (2) quality is lost, especially by adding aliasing and a loss of sharpness, by upsizing the now-700x460 back to 720x480. And then interlace is also screw up if interlaced, the video becomes an unviewable mess.

You cannot just arbitrarily crop to random sizes.
Ok, so maybe cropping is the wrong word. I was talking about lopping off those pixels and outputting say 700x460. I get that for something like DVD this is bad. But I expect to play these files on computer screens, phone screens, and maybe a 1080p TV. So the SD standard resolution becomes irrelevant. I don't really see what is superior about having a 720x480 (or 640x480) file vs 700x460 (for example).

Quote:
Originally Posted by lordsmurf View Post
No. It's horizontal. And VHS is arguably not even 352x480, much less 640 or 704.

This statement makes no sense. Nothing is "stuffed".

The problem here is the way capture cards ingest (usually due to drivers). The ATI AIW cards, for example, were intelligent about active pixels and aspect. But your average capture card is pretty stupid, if not capturing 720x480. Most cards are dumb about any other size beyond 720x480, as that's all the chip or driver was optimized for. If you attempt other resolutions, odd things can happen, mostly AR/sharpness/aliasing issues.
Understood that the VHS source does not have 640 or 720 pixels worth of horizontal resolution. But once captured at that resolution, there is unique data in each pixel. Resizing from 720 to 640 requires "stuffing" 720 pixels worth of data (including noise) into 640 pixels. By stuffing, I mean using some sort of scaling algorithm. Sampling 640 pixels per line instead of 720 from the get-go on the capture card should result in a better image.

Are you suggesting that the capture card is actually just always capturing 720 pixels and scaling down to 640 internally when using a lower resolution? If so, then it makes sense just to capture the full 720 for our lossless initial file.

My 720 captures have black bars on each side. I'm guessing this is the 720 vs 704 width discussed elsewhere. If I am understanding correctly, 704x480 should be resized to 640x480, not the full 720. The black bars are not part of the 4:3 aspect ratio. Is that right?
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  #29  
01-31-2021, 10:21 PM
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Quote:
Originally Posted by thefrog1394 View Post
I was talking about lopping off those pixels and outputting say 700x460. I get that for something like DVD this is bad. But I expect to play these files on computer screens, phone screens, and maybe a 1080p TV.
Again, still not understanding...

It's NOT just DVD (or to be precise, the DVD-Video format; "DVD" is just the disc).

Phones don't play video.
TVs don't play video.
Websites don't play video.

Players play video.

Players often will not understand non-standard resolutions. Backing up even more, editors and encoders often do not understand non-standard resolutions. Something like 700x460 would require 4x4 DCT encoding (using another random number, like 698x458, would be 2x2 encoding). But players may insist on standard 16x16 block size, and stretch the content to 16x16 regardless of AR flags. Or 8x8, 4x4.

Even if 2x2 is allowed, the player may only understand a certain number of AR flags, like 4x3 or 16x9 -- not whatever weird AR that 700x460 would plop out.

Quote:
But once captured at that resolution, there is unique data in each pixel.
No.

The pixels are a palette. The actual resolve is not pixel matched. So a 300x480 standard (max) resolution VHS would have pixels where content is essentially duplicated. 2+ pixels would be near identical content. Remember, analog video doesn't have pixels.

Quote:
Resizing from 720 to 640 requires "stuffing" 720 pixels worth of data (including noise) into 640 pixels.
No.

Quote:
By stuffing, I mean using some sort of scaling algorithm.
You have to separate the content from the pixels. Scaling the content won't really be affected by a downsize. At most, your may introduce some aliasing, but not at those resolution with a mere 704>640. And the deinterlace will make this a moot argument, as that's far more drastic.

Quote:
Sampling 640 pixels per line instead of 720 from the get-go on the capture card should result in a better image.
In theory. But not in practice.
Theory is nice to fill books, have debates, etc -- but I care about practical application.

Quote:
Are you suggesting that the capture card is actually just always capturing 720 pixels and scaling down to 640 internally when using a lower resolution? If so, then it makes sense just to capture the full 720 for our lossless initial file.
Correct. That happens. Go back some decades, and look at the BT8x8/CX cards, which couldn't even handle 720x704 correctly, and fubar'd the AR.

Quote:
My 720 captures have black bars on each side. I'm guessing this is the 720 vs 704 width discussed elsewhere. If I am understanding correctly, 704x480 should be resized to 640x480, not the full 720. The black bars are not part of the 4:3 aspect ratio. Is that right?
Crop 720 to 704.
Resize 704 to 640.

This assume the AR was correct to begin with. I've seen cameras that record the wrong AR, and the 720>704>640 would actually make a mess. So content matters. You'll need to locate some geometric (example: a round clock) to confirm the footage is actually standard.

Lots of people monkey-up video, including pros (and "pros" aka quacks), due to misunderstanding. I've made some mistakes in my past as well, everybody does or will, but I don't double-down like some of these clowns I see online. I'm also very careful, test and view. I never just batch a job, only to later realize I made a mistake and have to redo it (or worse, shrug it off, just do a terrible job, as lots of hack "professionals" and "services" do).

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  #30  
02-01-2021, 01:17 AM
latreche34 latreche34 is offline
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The whole purpose of resizing to 640 is to have a square pixel, in other words it forces the 4:3 AR so dumb devices will display it correctly, This was an issue back in the day but now I haven't come across a device that doesn't recognize the SAR flag, So far I've tried 2 iPhones, 2 Android phones, 2 Samsung Tablets, 3 LG TV's, nVidia shield, PS4, Xbox, a media player built in ATSC tuner and they all recognized the SAR flag and displayed 704x480 in a perfect 4:3 ratio. If you don't have the need to don't resize to 640 just leave it at 704 and assign an aspect ratio flag sar=10/11 (sar=12/11 for PAL/SECAM).
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  #31  
02-01-2021, 01:38 AM
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Quote:
Originally Posted by latreche34 View Post
The whole purpose of resizing to 640 is to have a square pixel, in other words it forces the 4:3 AR so dumb devices will display it correctly, This was an issue back in the day but now I haven't come across a device that doesn't recognize the SAR flag, So far I've tried 2 iPhones, 2 Android phones, 2 Samsung Tablets, 3 LG TV's, nVidia shield, PS4, Xbox, a media player built in ATSC tuner and they all recognized the SAR flag and displayed 704x480 in a perfect 4:3 ratio. If you don't have the need to don't resize to 640 just leave it at 704 and assign an aspect ratio flag sar=10/11 (sar=12/11 for PAL/SECAM).
Yep.

And the same players can choke on oddball resolutions that are not 16x16 or 8x8 macroblocks with standard DAR. Sometimes more DCT are understood, sometimes not. Often not.

So you have double the reasons to leave aspect alone. Just mask overscan noise, enjoy the remaining 95%+ of the visible content, and make your own life easier.

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  #32  
02-01-2021, 10:12 PM
thefrog1394 thefrog1394 is offline
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Ok, so sounds like the issue with odd-size files is the mpeg encoding/decoding step. Fair enough. I don't love the "picture framing" that comes from viewing 4:3 content with black bars at the bottom/top on a widescreen but oh well. I do wonder if something like 704x464 would be a good answer though (multiple of 16). But looking at my sample, I might lose 8px of content going that route. 704x472 looks about ideal, but then I'm looking at a multiple of 8 vs 16.

Over at VH I saw a thread with some commentary on lower capture resolutions. It basically sounds like cards always capture at "standard" 720px internally, regardless of what the capture resolution is set to. Seems reasonable enough. In which case saving the full 720px vs blindly scaling as part of the capture step before any filtering etc makes perfect sense. If PAR is truly supported universally with mp4 these days, then I'd consider leaving at 704 with the correct PAR set. Based on my searches, it sounds like this could be an issue with some Plex clients which is a problem. But I guess it's worth me testing a bit first.

To be clear, I do plan on saving the originals for any future editing, etc. But the reality is that the output progressive h.264 encoded files will likely be the only files ever viewed. So I'm looking to optimize compatibility and quality on those as best I can.
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  #33  
02-01-2021, 10:35 PM
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Quote:
Originally Posted by thefrog1394 View Post
Ok, so sounds like the issue with odd-size files is the mpeg encoding/decoding step.
No, not MPEG. All encoding, including Huffyuv, H.264, etc.

Quote:
I do wonder if something like 704x464 would be a good answer though (multiple of 16).
No.

Quote:
704x472 looks about ideal,
No.

Quote:
Over at VH I saw a thread with some commentary on lower capture resolutions. It basically sounds like cards always capture at "standard" 720px internally, regardless of what the capture resolution is set to.
Sort of correct. It varies. For example, the ATI AIW cards, the Theatre chips, had native chip of about 712x480, and padded out 8 pixels to get to 720. You can see this offset in some of the early drivers.

Quote:
Based on my searches, it sounds like this could be an issue with some Plex clients which is a problem.
Yep. Plex is a player. Players have issues.

Quote:
But I guess it's worth me testing a bit first.
Yep. Just realize v2.0 of the player, or an update, or another shiny new upgrade brand player, may totally tank your past work. It's sort of like color correcting the video to your monitor, instead of to the video. Because that monitor will go someday.

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To be clear, I do plan on saving the originals for any future editing, etc.
Well, there you go.

I don't like keeping Huffyuv archives, my collection is too vast, so I archive the Huffyuv as high bitrate MPEG 422@ML, masking beforehand to appease the encoding. (Noise aka overscan = wasted bitrate, lower quality.)

Quote:
But the reality is that the output progressive h.264 encoded files will likely be the only files ever viewed.
Probably. That's why I archive as MPEG, as I can watch those with time consuming re-encodes to H.264, for the few times I'll likely view them (noting others will view them, not just me).

Quote:
So I'm looking to optimize compatibility and quality on those as best I can.
Then mask. You have the guide, in this thread, use it.

Quote:
Fair enough. I don't love the "picture framing" that comes from viewing 4:3 content with black bars at the bottom/top on a widescreen but oh well.
It's generally less than 10 pixels after re-center. I don't understand the freak-out over such a slim area. If you're watching on a HDTV or a phone, you won't even notice it. It arguably the least distracting "error", given how Youtube is so full of butchered videos anyway.

The next comment is usually "how do I make my VHS into HD and widescreen?" -- same mentality, usually from the same folks. Unwillingness to have slight imperfection, but totally willing to completely fubar the image and quality to chase a unicorn. Again, I don't get it.

Don't be that (weird) person.

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