downsizing encode losing something?

[maxwell3]

Ive been capturing at 720x480 from vhs with iuvcr/huffy then using tmpg dvd source to encode at 352x720 . It seems to give a better end result . But I just discovered something If I open the encoded mpg in wind media player the side are squeezed in , but when I open it in win dvd or if I burn a dvd it looks fine . So Im wondering if Im doing a good thing or a bad thing by downsizing when I encode . Am I losing detail and it just subjectivly looks better ?

[Video Dude]

352x720 is not a valid DVD resolution. I think you mean 352x480.

352x480 is generally acceptable for VHS captures. The reason it looks distorted in media player is that media player does not adjust the aspect ratio, it plays it back at 1:1. Your dvd player adjusts the aspect ratio to 4:3.

Yes, you loose detail everytime you resize. It looks better because it is blurring it and causing some artifacts to be smoothed but detail is lost.

In theory, if you want the highest quality leave it at 720x480 with a bitrate about 6500 and do some light filtering.

But do what looks better to your eyes, because you will be the one watching it. If you like 352x480, use that.

[maxwell3]

Thanks Yes your correct I meant 352x480 . I was told by someone in another post that the reason it looks better is because theres less space so the average bits per pixel were increased . But if Im losing detail maybe I should leave it at 720x480.

[davexnet]

you are definitely not losing detail.
Don't forget, regular vhs only has about 250 horizontal lines
of resolution in the best case, with s-vhs a little more.

If it's ntsc, 352*480 is good to capture both fields, or 352*240
for the single field. Even 320*240 is good.

Dave

[Video Dude]

Resizing has the possibilty of causing artifacts and causing jagged edges on some types of material (The resizing engine in TMPGEnc is not the best). True, if you want over 4 hours on a DVD then resize to avoid blockness from lack of bitrate, but if you are only going to do 1.5 hours then 720x480 at max bitrate is a better choice. You might not be loosing a significant amount of detail but you risk adding lots of garbage artifacts and smearing on high motion scenes or panning by resizing.

320x240 is not a valid DVD resolution.

But as I suggested to maxwell3, encode at the resolution (720x480 or 352x480) that looks better to you, because you will be the one watching it.

[maxwell3]

So far every time Ive downsized to 352x480 the encode comes out excelent. No artifacts or blockiness . I dont really see any loss of detail either but Ivce only do 2 comparisons . Ill do a few more and see . Thanks

[Video Dude]

Glad to see that you are getting good results. :)

[Wilbert]

you are definitely not losing detail.
Don't forget, regular vhs only has about 250 horizontal lines
of resolution in the best case, with s-vhs a little more.

If it's ntsc, 352*480 is good to capture both fields
Some comments:

1) vhs has 235 horizontal lines of resolution or a bandwidth of 3 MHz. Which equals to 2*3*52.666 = 316 pixels for NTSC. Since Nyquist is not exactly valid, this number is only an absolute minimum. The optimum will be higher.

2) The quality of the scaler of your cap card is also important. If you have an ati, bt8x8 or cx2388x you don't want to cap below ~400 to get good quality.

you are definitely not losing detail.
Wrong, you will loose detail.

[davexnet]

thanks for the info. I wasn't aware of the formula.
Regarding this: 2*3*52.666 = 316 pixels

I've never seens this discussed before.

Dave

[Wilbert]

These kind of arguments will be added in the new version of the analog capture guide. You will have to wait a few weeks before it's ready.

[maxwell3]

Okay Im confused . Im using an msitv@nywhere to capture at 720x480 then when I encode( tmpgnec dvd source)I downsize to 352x480. The question is am I losing detail when I encode and downsize ? . Should I do more tests or does someone have a definite answer . ? Thnaks to everyone who replied

[Wilbert]

The question is am I losing detail when I encode and downsize ?

If you encode you are loosing detail, if you downsize you are loosing detail. It might be acceptable though. Just try with and without downsizing. Compare it on your TV, and see which one is the most pleasing to watch.

Just follow the advice of Video Dude, but don't cap at 352x480 if your aim for 352x480 (do your resizing during post processing).