PAL resolution

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Yarn366: 2017-08-27 05:04:02 pm

2017-08-27 03:07:06 pm

I think this is the correct board for this topic.

I noticed that for D1 videos, SDA recommends encoding NTSC at 640x480, and PAL at 704x576. If the idea of these resolutions is to have a 4:3 aspect ratio and a 1:1 pixel aspect ratio ("square" pixels), then 704x576 fails at this, because its aspect ratio is actually 11:9 (704 / 576 = 1.22..., or 11:9). For PAL video to be encoded in this manner, it would have to be 768x576 (768 / 576 = 1.33..., or 4:3). Likewise, PAL D4 would need to be 384x288 (384 / 288 = 1.33..., or 4:3) rather than 352x288 (352 / 288 = 1.22..., or 11:9).

Of course, I might be missing something important here. (And yes, I am aware of aspect ratio tags, though I don't think I've seen any PAL runs on SDA that use them.)

Thread title:

nate

2017-08-31 11:22:01 am

read this section for where those numbers came from: https://en.wikipedia.org/wiki/Pixel_aspect_ratio#Digital_video_processing

basically it's an artifact of community standards for working on analog video from 10-20 years ago. if you don't want to use aspect ratio metadata in mp4 (like yua does) then you can output with square pixels to achieve 4:3, in other words resizing to 640x480 before encoding, since that is what the games are probably running at anyway. 768x576 is problematic because you would be stretching the input horizontally before encoding. if you think the kb is unclear on any of this by all means go ahead and edit it.

Yarn366

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Yarn366: 2017-09-01 04:35:01 pm

2017-09-01 03:58:07 pm

What brought this to my attention is that the Metroid Prime PAL runs on this site that are encoded at 704x576: their aspect ratio is 11:9 rather than 4:3, and circles (like Samus's morph ball) look like slightly vertically stretched ovals rather than circles (although they're close, and nowhere near as ugly as 4:3 stretched to 16:9). Then again, they're older runs, and the tools used at the time may not have supported aspect-ratio tags. At least the latest versions of Anri-chan and Yua both apply the tags when necessary, based on my tests.

Still, wherever the KB says to encode NTSC video at 640x480 or 320x240 (both of which are 4:3), it says to encode PAL video at 704x576 or 352x288 without ever mentioning that those resolutions aren't really 4:3 and thus require an aspect-ratio tag to display at 4:3. One of these places is in the Resizing section of the AviSynth guide, where the language implies that 704x576 actually is 4:3. Unfortunately, I don't know how to add an aspect-ratio tag to an MP4 file during encoding. (Yeah, I realize that almost everyone here is probably using one of the automatic methods, but I feel it's worth mentioning because this method is presented as a processing option.)

Quote from nate:

in other words resizing to 640x480 before encoding, since that is what the games are probably running at anyway.

I doubt that's the case for 50 Hz games, unless A) the image is letterboxed, as with PAL 2D consoles, or B) the image is scaled from 480 lines to 576 lines, which would probably happen only on 7th-gen consoles and later. A horizontal resolution of 640 pixels is still possible, though.

Still, wherever the KB says to encode NTSC video at 640x480 or 320x240 (both of which are 4:3), it says to encode PAL video at 704x576 or 352x288 without ever mentioning that those resolutions aren't really 4:3 and thus require an aspect-ratio tag to display at 4:3. One of these places is in the [url=https://kb.speeddemosarchive.com/AviSynth#Part_7:_Resizing]Resizing section of the AviSynth guide[/url], where the language implies that 704x576 actually is 4:3. Unfortunately, I don't know how to add an aspect-ratio tag to an MP4 file during encoding. (Yeah, I realize that almost everyone here is probably using one of the automatic methods, but I feel it's worth mentioning because this method is presented as a processing option.)

[quote="nate"] in other words resizing to 640x480 before encoding, since [b]that is what the games are probably running at anyway[/b].[/quote]
I doubt that's the case for 50 Hz games, unless A) the image is letterboxed, as with PAL 2D consoles, or B) the image is scaled from 480 lines to 576 lines, which would probably happen only on 7th-gen consoles and later. A horizontal resolution of 640 pixels is still possible, though.

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