Thank you (as always) for confirming it lordsmurf :-)
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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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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.) Quote:
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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. |
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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. |
No, you're still not seeing it... :wait:
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You cannot just arbitrarily crop to random sizes. Quote:
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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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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:
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:
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Theory is nice to fill books, have debates, etc -- but I care about practical application. Quote:
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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). |
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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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. |
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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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:
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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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