I need some help, please.

bobbys wrote on 8/7/2004, 12:31 AM
I've asked this question before and got no response. so, i'll rephrase it another way.

Why is it that when you capture at 720x480, encode to mpeg @ 720x480, burn it to dvd and then play it on a TV that is a 13in the picture looks great. but, when you take that same disc to a different TV that is a 55in and play it, the picture looks bad. (Pixelated)

I've been expirmenting with capturing at different sizes (some were up to 2016x1512) to see if maybe that was the problem with the output quality. I just don't know enough about this subject to fully understand it. So, does anyone care to explain the theroy of capture and the final output on the DVD to me or does anyone have a link to help me go away for a while:)

Comments

farss wrote on 8/7/2004, 1:12 AM
It's pretty simple.
All NTSC DV25 is 720x480. DVDs are the same. Trying to capture at a higher resolution will achieve nothing. How those pixels are sampled from the original image does vary but to delve into that gets more complicated. Suffice to say that what in each pixel and how it is stored improves as you go up the scale in terms of cameras and recording systems.

As to why the images look worse on a bigger screen. Well typically most small TVs do not have enough bandwidth for you to see the problems. Hopefully a 55" set has better video amplifiers etc so the defects are not ebing smoothed out. Same thing happens with audio. What sounds fine on a cheap car radio or PC speakers can sound horrid on a good HiFi.
Also you tend to stand a lot closer as a ratio of screen size to the bigger TV, the image is larger in your field of view so you're much more focussed on it.
But, your DVDs shouldn't look pixelated. Two things we need to know. What is the source material? How much of it are you trying to fit onto a DVD? And what bitrate are you encoding at?
Most likely the pixelation isn't a lack of resolution in a spatial sense, its the temporal aspect of mpeg-2 compression that can cause this and the results are affected by the amount of motion and noise in the images offset against the available bit budget to fit the data into.

Bob.
VegasVidKid wrote on 8/7/2004, 1:18 AM
It shouldn't look **that** much worse, although it will be easier to see imperfections on a larger screen. Even low resolution images will look no different than high defintion if you watch them on a small enough screen.

The standard frame size for DVD (incl Hollywood movies) is 720 X 480, but the quality of their original source material is better than yours and the encoding is better. However, if you are using the proper/normal settings, a DVD should not look much different than the original tape when captured ,edited, and encoded to DVD MPEG2 format with Vegas.