Usually, when capturing from NSTC SD analog sources, it is custom to resize the captured footage to 640x480 from 720x480 to compensate for the 0.9 pixel aspect ratio found in CRT displays. However, when capturing from SD consoles, such as the Playstation 2, there are black bars present around the rendered game video. This is presumably present to protect the video from overscan found in CRT displays. I was uncertain how to handle the video when it came to cropping and resizing so I made a few tests after a discussion on matter.
I captured a video of PS2 game Yakuza 2 at 720x480 and cropped it to 640x480, and left the black at the top and bottom of the picture alone. Analog NTSC video usually uses 480 lines with 720 samples per line, so unless you know otherwise, you should always capture it at 720x480.
It turns out that the PS2 renders the image at 640x448.
I wanted to confirm that 640x480 was the correct resolution, so I compared an image from the captured analog video to an image from the game being emulated.
Holy shit does that look better emulated, but more importantly, it's at the proper resolution and proportion.
We crop the 720x480 picture to 640x448, then resize it to 640x480.
And as we can see, though the quality might not be, the proportions and resolution are identical.
The issue of widescreen came up in the discussion as well, so I tested that too. SD widescreen is just a trick where the horizontal aspect of the image is narrowed so that it looks proper on widescreen displays. When configured for this in the game, we can see this effect in both the emulation and the analog capture.
We crop the off the black of the analog capture and resize it to a 16:9 resolution, in this case 640x360, and we do the same to the emulation.
And there we go, same proportions and dimensions.
If you're actually encoding a 16:9 video from an analog NTSC source, you should resize it to 854x480 or 856x480 instead, that way we don't lose any vertical information.
I have yet to confirm for other consoles, but for recording from the PS2, unless you have a game like GT4 that does 1080i or something stupid, I think I can say that I'm pretty sure that this is the way to record analog from it, if it wasn't obvious to everyone already and I'm just dumb.
Record the game at 720x480, crop the black borders on all sides and resize to 640x480 for 4:3 or 854x480 for 16:9.