Newbie question re: aspect ratio and ipods

[waysid]

Hi,

I could really use some help with the following problem:

I want to convert an widescreen ( 608 x 336 ) avi to an h264/mp4 format ipod video, that I plan to play using the TV-out mode on my iFlip video player. The iflip is basically just a screen with a docking port for the ipod. It has a native resolution of 480 x 234 and can display in 4:3 or 16:9 ( the default ).

I have no problems using megui to do the conversion but I have found some weird problems with aspect ratio.


So what I tried to do the first time is just convert the video and leave it in its native resolution. I put the Ipod setting on widescreen and then put the iFlip setting on 16:9. What happened was that I got a stretched letterbox-style image on the iFlip? I assumed that since the video was originally in 16:9 and because I used the widescreen settings on both the ipod and iflip that the image would correctly fill the display. Not the case, but I can't understand why.

I have found that if I want images to display correctly, I need to convert the video to 4:3 ( 448 x 336 ). Then when I play it on the ipod ( widescreen mode ) and iFLip (16:9) mode it fills the screen and looks "correct". This seems weird to me that I would have to make it 4:3. Any thoughts?

Also any thoughts on how I would get the best image in general using the ipod and iflip would also be appreciated.

Thanks for reading

[Skelsgard]

Considering that you say that the image is stretched, if you iFlip is showing a display selected as 16:9 with letterboxing, is doing right then.
480 x 234 is not 16:9. 480 x 270 is. So in order to play a 16:9 movie with proper DAR in a 480 x 234 it has to fill both sides with letterboxing as a 234 height means a 416 width (64 pixels shorter).
But as it is showing it stretched (wich will contradict the letterboxing), the iFlip is filling those 64 pixels with the stretching, breaking the 16:9 DAR.
Is it possible that your iFlip literally says that supports widescreen and not 16:9? cause they´re not synonyms, although many people believe they are.

It would be usefull if you could post the next situation for comparison so we can provide you with further help:
How does it looks in the iFlip when the movie is 16:9 and you select:
a) 4:3 iPod - 4:3 iFlip
b) 4:3 iPod - 16:9 iFlip
c) 16:9 iPod - 4:3 iFlip

Cheers.

[waysid]

Thanks for the response.

Yeah the iflip definitely does call it 16:9 mode, which is weird considering the resolution isn't really 16:9 :-)

I don't have my setup with right now so I can't check out the scenarios you mention but I do remember what happened when I try C.

When 16-9 on the ipod and 4:3 on the ipod, results in the video being displayed without stretching, but there are black bars on both sides and on the top and bottom. A little bit of the image also seems to be cropped by the black bars on the top and bottom.

Also maybe worth noting, is the 16-9 on the ipod, 16-9 on the iflip, gives the same size bars on the top and bottom, its just the the side bars are gone and the image is stretched. ( this was the original scenario I described in my first post ).

I will post the results of A and B tonight, when I get a chance to play it with it again.

Thanks again.

[Skelsgard]

Yeah the iflip definitely does call it 16:9 mode, which is weird considering the resolution isn't really 16:9 :-)
I hate when they do that, it only confuses even more the unexperienced consumer.

When 16-9 on the ipod and 4:3 on the ipod, results in the video being displayed without stretching, but there are black bars on both sides and on the top and bottom. A little bit of the image also seems to be cropped by the black bars on the top and bottom.
4:3 on the iFlip, right? I can assume that 4:3 means for the iFlip that it must not resize the input whereas 16:9 just means resize to fit width. Anyway, letterboxing to be proper should be in either the horizontal plane or the vertical one, not both.

Waiting for the next tests.
Cheers.

[waysid]

Thanks again for the help. Here are the full results of the tests you asked me to try.


A) 4:3 Ipod/4:3 iFlip - the aspect ratio looks fine, there are black bars on each side ( to be expected since its 4:3 on the iFlip ), but the picture is cropped, its definitely missing pixels on the sides and possibly the top and bottom. I have confirmed that this is the same image that appears on the ipod screen if I don't use the iflip.

B)4:3 Ipod/16:9 Iflip - the image fills the full screen but its stretched.

C) 16:9 Ipod/4:3 Iflip - bars on top and bottom, image and bars only appear in middle portion of the screen, so it looks there are bars on the sides.

So what I have concluded:
- based on whether the iFlip is 16-9 or 4:3 will dicatate how much of the screen is used. 4:3 mode doesn't use all of the horizontal width.
- using 4:3 mode on the ipod crops and/or zooms the widescreen image, and this cropped image is what is sent to the iFlip. It displays this image at the correct AR if the iflip is set to 4:3.

Anyway, does that help? Any thoughts.

[Skelsgard]

It confirms what I thought about the iFlip calling 16:9 to a basic stretching, whatever the resulting DAR is.
The 4:3 Ipod/4:3 iFlip mode should result in the less-worse ground for viewing with proper DAR, if it doesn´t bother you the side letterboxing.

Cheers.