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Old 28th August 2003, 15:13   #1  |  Link
dvd_maniac
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Join Date: Feb 2002
Location: northeast/usa
Posts: 825
is this true? resolution myths?

got this from http://www.dvdrhelp.com/forum/userguides/98177.php
I capture with ati aiw 9700 pro from digital cable and directv sat. I use s-video and if this is true I should only cap at 352x480 if I want to author dvd with it?
Now, it is a perfect opportunity to clarify a myth here: There is no way to grabb from any analogue source (including TV broadcasts) and with the use of "S-Video in" to get a usefull resolution beyond 384 X 576/480.
The reason for this, is that in analogue technology, there are no horizontal lines like the digital world, but horizontal DOTS. 720 dots in a raw, creates what we call a line. With the analogue transmissions, if a dot is missing in the raw, there gonna be no replacement, just a null dot, a nothing. The lenght of the raw, gonna be always the same with or not some dots. For example:

A line with all the dots: ...........................................................
A line with some dots missing : ... ............. ............. ..................... ...

In theory all types of connections/cables are capable to carry a picture of CCIR-601 resolution from a source to a screen, but there gonna be loses in the dot raw line like those in the example. Those loses are more for composite, less for S-Video and even less for Component and RGB. It is not easy to expain it further in a simply post, maybe a future article
With S-Video, those loses are about 1/5 of the video in theory. In practice and mainstream cables/connectors, is more, about 2/5 or the original info.
So you end up with 384 horizontal usefull dots X 576/480 vertical lines. And becase in digital world only the usefull info counts, any grabb with the use of S-Video beyond 384 X 576/480 is a fake!
If you want source on higher resolutions, you can experiment with DV, DVB transmissions (when you grabb direct the stream with the use of special hardware), DVD - Video (ripping) and source which came from Component adaptors or RGB ones. The full Euroconnector cable (known more as SCART) includes sometimes the RGB info, but a Full SCART to SCART cable required , with high quality parts and those cables costs a lot!. Also, the difference ain't easy noticable on a TV, but is very noticable from the encoders!
Overall, don't expect higher resolutions beyond 384 X 576/480 with the use of S-Video! It is practicly impossible to have them! And because 384 X 576/480 ain't a supported resolution in any optical media, go straight for 352 X 576/480.

Last edited by dvd_maniac; 2nd September 2003 at 03:04.
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