Is it possible to fix the display resolution of a PDF file at 96 pixels/inch by some means?
I am developing some e-learning content which I would like to distribute as interactive PDF files. I intend to use InDesign CS5.5 for the layout work and have been creating some test screens.
It falls apart when I add movies onto my pages. Once saved as an interactive PDF file and opened in Adobe Reader the quality of the movie is very dependent on the page display resolution set in the individual user's preferences.
If they have their preference set to anything other than 96 pixels/inch the movies look poor. We develop the movies on our Macs at 72 pixels/inch and can overcome the change in resolution to 96 pixels/inch by changing the page setup to 75%. The resolution though is out of our control and i wondered if we could overcome this by some neat scripting.
Simple answer is "no, but there's another way".
PDF pages display in physical units (points) so the concept of "100%" is actually meaningless on screen - the chances of it being 1:1 pixels are vanishingly-small even on a predictable set of hardware, and in Acrobat or Reader a "100%" scale is supposed to mean "a 210mm wide page is shown 210mm wide" - however as it has no idea of the physical size of the monitor, it's a moot point. It is certainly not the same as "100%" in Photoshop, which means "one photo pixel = one screen pixel".
Instead, if you use a different player widget to embed your videos in Acrobat, you can set the video itself to use 1:1 pixel scaling (provided the screen rectangle is large enough of course). Flash is happy to work with pixels even when the PDF it's living inside is not.
Thank you for your very interesting reply. I will look at the player widget and see how this will work for us. It may be that we could write our own player in Flash to host the video content.