Quote:
Originally Posted by kwag
Hi incredible,
Can you verify this
Because to my understanding, the image will always be resized on the TV, to do the overscan blocks. So the image is always streched both horizontally and vertically. So if we encode with "Resize" or "Overlap", the final image is still going to be stretched horizontally AND vertically on the TV, no matter what, because it's an internal TV function.
-kwag
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Well lets see if I can explain in english...
The basic (for example PAL) interlacing is build on 50 Lines at 50Hz which give you 25 FPS (pictures) PAL for example @ 704x576 and thats the point. In (full PAL) digitally captured pictures you got an interlaced image at 576 high if you scale down (not cropping) the size for the amount of 50 Lines proportionally to the space is trashed. (Its like dots per inch in Photoshop, .. I only use this comparison to explain
)
You can let out every 2nd line to obtain 288 px but also then its not interlaced anymore but also correct handled cause you did not "resize" to 288 but you let out every 2nd line and thats for example they way a direct capture at 352x288 works (PAL). If you capture at 768x576 and want to scale to for example 640x480 you HAVE to deinterlace before.
What we want to receive is that the architecture of the 50 Lines at 576px of picture high will be untouched and we can if we only resize the widh to 480 .. so we get a Picture at 480x576 which is still interlaced and in this untouched state it appears more sharpen than an interlaced one.
Ok by watching it on a PC you can see the comb effekt, but who cares, cause our intention is to make CDs watchable with a DVD Player ... and not CD with Dvix which will only be seen on a PC Screen.
But you have to use for example asharp with caution! Cause asharp sharpens horizontally and vertically... and if you sharp an interlaced picture at is vertcal to much .. you can see flickering when watching on Tv!
So it would be better to make a combination of asharp() and unfilter(only horizontally) .. this will give good results.
The picture then will not be scaled in the DVD Player internal as we "digitally" think, no ... it will be converted using the d/a converters to give an analog signal to the Tv and the Tv scales the "analog" picture as a whole and thats the difference. So every Tv scales the picture more or less and thats why they use the "cache" which normaly takes about 10% at the borders of the screen .. calles overscanning
So we put on the untouched (at the high *576*) stream a black layer at the borders .. and this we call overlapping.
So with all this we get a correct interlaced 3/4 PAL 480x576 interlaced picture including correct set overscanning borders, ready to convert to mpeg2 which can handle interlaced frame architecture.
Maybe someone sees now a misunderstanding, but I tried to explain this complex materie in my best english words