Weird PC vs. DVD player cropping issue

[GRisdale]

Working on a video and dance piece recently I encountered a troubling phenomenon:

 

The video for the show was on a DVD. In rehearsals I had played this back on a laptop, going to the projector (Sanyo XP56) via VGA cable. All worked fine. When it came to the tech I intended to use the in-house DVD player (a Dennon, not sure of the exact model) connecting via component video. The video looked strangely different on the projection. At first I put it down to the projector reading the resolution differently as from the PC it would obviously be different even though the video res was the same, but when I tried to fix this by refocusing I noticed that the left and right edges of the video were being cropped off... Tried a different DVD-Player (an LG), same problem.

 

Not having the time to mess around I just went back to using the laptop which worked fine, but would like to know what caused the cropping and how I might prevent this in the future (I'd feel happier using a DVD-Player rather than Pc based laptop...)

 

Thanks in advance.

 

Gareth.

[Nicktaylor]

The only thing I can suggest is to get something like movie and play that on both players to see if that crops on one. I suspect it has something to do with the output setting when you burnt your disk. Could even be something as simple as the wrong aspect ratio which you might not see on an effects type projection rather than a proper film. Wide screen to 4:3 and vice versa can cause all sorts of problems with the edges of pictures! :)

[GRisdale]

Had thought it may be aspect ratio related, but: the video plays 16:9 (as it should) on a laptop or PC. On the DVD player I tried both 4:3 and 16:9 setting but both still had edges chopped off... Maybe I needed to delve deeper int othe projector menu...

[Nicktaylor]

I have a projector and when I tried to show a home movie of a holiday it crops the edges. Nothing I did to the visible menus settings helped. I think it is more the out put of the player which needs changing! Play a normal DVD and no problem

[Toxopholist]

Hi Grisdale,

 

I suspect that your issue maybe down to the differing ways the projector processes VGA versus Video signals. The Projector when it is looking at a VGA signal will attempt to scale the image so that it it has the whole image on display so the image will show the very first pixel and last pixel of a scan showing absolutely every pixel in between (assuming the input is scaled correctly) and will let you make adjustments to ensure this.

 

Video is handled a slightly different way, the image is slightly over scanned (see this wiki for a better explanation) by default and therefore you don't see as much of the image, and unfortunately I don't think you can make any adjustment on the sanyo projectors. Some have timing adjustments often labelled as start period or VBLANK.

 

A lot of professional video monitors have an under scan button on them so that as a video op you can check what the real edges of the image are as well as what most video equipment will see.

 

I hope this is a little clearer than mud,

 

Charlie

[henny]

heres what the problem will be,

 

the projector is 4:3

the laptop is 4:3

The dvd disk is in 16:9

the DVD palyer outputs whatever the disk is, eg give it a 4:3 disk it will spue 4:3 ect

 

when you play the dvd on the laptop it is either doing one of the following to output a 4:3 image

 

basicley streching it taller to fill 4:3

or

Leterboxing,showing the 16:9 in the center of the screen with black top/bottom)

 

the problem you were getting is that the dvd palyer would have been sending a 16:9 siginal and the projector would have been croping just a 4:3 chunk out of the middle , thats how normal tv brodcasts work , they film in 16:9 but work with a 4:3 safe area in the center of the shot, if you look at say BBC news for example when viewed as 4:3 the clock an the on screen graplics start at the edge of the screen, but when you view it as 16:9 on a 16:9 dispay there is a gap to either side

 

ian