View Full Version : Iso Aspect Ratio Problem
Hi
I've only been using XBMC for a few day's but I am a HT custom installer so i have a fair knowledge of aspect ratios. I have ripped several DVD's to ISO files using DVD shrink. When playing back the ISO's through XBMC all appears well until closer inspection reveals that the asspect is different, especially on 2.35:1 movies. Everything appears correct size wise however the actual image is wider and narower than the origional DVD to the point of even giving more picture info either side of the screen. I am using a Sony 4:3 PAL screen with the XBOX set to 4:3 with PAL 60 switched off as this the only way I can achieve a 576 line image. I am using the XBOX scart cable feeding RGB to the TV.
Any idea whats going on here. I have tried altering the pixel ratio settings and the over scan settings but nothing gets it the same as the origional DVD. Is this a problem with ISO files and should I rather rip to a different file type?
Any ideas would be most appreciated.
smcnally75
2008-01-28, 20:32
I'm in the industry as well and have noticed the issue. It happens with iso and vob files (I haven't tried any others). I've mainly noticed it on 16x9 movies because there is still a 1" black bar at the top and bottom of my 16x9 screen. I went into screen calibration and fixed it there though.
Hi. Thanks for the reply. Do you mean screen calibration in XBMC or on your display. I've tried it in XBMC but slthough it helps the ISO image it screws up the normal XBMC interface.
smcnally75
2008-01-28, 21:20
IIRC, I did it while watching a movie through the menu system. I'll double check though when I get home tonight.
Ok thanks. I would love to solve this one.
have you been cycling through the different display modes?
during fullscreen playback this is done by hitting Y on the gamepad or Enter on the remote. XBMC can do a variety of different things with regard to making the image fit onscreen, and sometimes I have noticed you have to play with it a little.
Yip I've tried the display modes with no luck.
jmarshall
2008-01-29, 00:56
You've calibrated to remove the overscan.
DVDs are encoded with overscan embedded into the video frame. This is an absolute necessity, as the actual 4x3 or 16x9 frame is NOT 720x576 pixels large.
Thus, you are seeing things you really shouldn't be - picture data that is outside of the 16x9 frame but exists on the DVD.
If you don't calibrate at all (my preference) then what falls into the overscan area is normally what is meant to fall into the overscan area, assuming your viewing device doesn't have some insane overscan on it.
In either case, aspect ratio has nothing to do with it - all that is happening is that the movie is being reduced in size a bit so that there is nothing falling in the overscan area.
Cheers,
Jonathan
I had a similar problem (I think). XBMC was the only input/output that changed the size of the video. My SatTV and DVD player produce black bars the same size, whereas XBMC makes the black bars taller (less image). I had to add a fair amount of overscan to get the black bars the same size as the other inputs. I'm not convinced the aspect is the same as SatTV/DVD Player, but at least black bar height is consistent. I'd have to do a side by side comparison to see if the DVD player is displaying more/less image than XBMC. I do believe that a lot of overscan is applied to video appliances/TV's - so it could just be that.
Overall, I currently very happy. If I had to comment on video weirdness, it would be interlace/deinterlace issues. My DVD player (now 11 years old) does a better job at this function than XBMC. When I first saw the wavy edges/stripes around the video, I thought there was a problem with my ripping. "Blend" seems the best option for me here - although none of the settings completely removes the issues like my DVD player. I'm no expert, so not sure why. While I don't want to hijack this thread, I have always wondered about this one ???
JM beat my reply, so that adds an answer to the reality.
Another thought...
Does increasing the overscan degrade the image?
jmarshall
2008-01-29, 01:18
OT: Your DVD player isn't deinterlacing. It's not changing the image at all. XBMC will also not need to deinterlace (or can use "passthrough" interlacing) assuming you don't touch the image output size or framerate. As soon as you do scaling then deinterlacing is needed in some respects. The "passthrough" interlacing should be the best for this. I can't recall offhand what the deinterlacing mode is that handles this is though.
Hi. Reply to Jonathan. Thanks for the input. I'm in South Africa, hence the delay in the reply. So what your basically saying is that on all DVD's there is actually a part of the image, with picture in it that is never usually displayed but XBMC is showing the full image hence the smaller size.
If this is the case then setting the zoom at the right level would achieve the same image. Give me a minute!
OK I've just tried adjusting the zoom and comparing with the origional DVD. Setting the zoom to 1.11 in the custom picture mode achieves pretty much the same image. It is moved up the screen slightlly about 5-7mm (not sure what that is in inches, probably about 1/4") but I can live with that.
Thanks a lot for the help, sorted.
Andy
OT: Your DVD player isn't deinterlacing. It's not changing the image at all. XBMC will also not need to deinterlace (or can use "passthrough" interlacing) assuming you don't touch the image output size or framerate. As soon as you do scaling then deinterlacing is needed in some respects. The "passthrough" interlacing should be the best for this. I can't recall offhand what the deinterlacing mode is that handles this is though.
O/T - Not sure I really understand this?? Basically what I'm trying to say is that my DVD player output shows no jaggies/combing/wavy line thingees but playing the same video through XBMC I get these (not always but some video is chronic).
So is XBMC scaling the video and creating these? I run the video using the "Normal" setting
Definitely don't know what's happening :no:
(Not wanting to hijack this thread - so if it's a problem can another thread be started?) I'd really like to understand what is happening and what it is I'm seeing.
My problems solved pretty much so your welcome to hijack the thread.
What TV system are you using and (NTSC, PAL), and is your display progressive.
Assuming these are ripped files what format are they and how do they play back on your PC. It could be an encoding problem. I've so far ripped a pile of DVD's to un compressed ISO's using DVD shrink, and now I've resolved the sizing issue they all look almost as good as the origional.
You may need to use DVD shrink with Ripit4me and DVD decrypter to rip some DVD's which of course you must own the origional of.
A