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Old 05-16-2006, 10:54 AM   #1
JoeDuncan
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Mplayer - 4:3 letterboxed video on 16:9 screen


Ok, I have a 4:3 TV, a 4:3 desktop monitor and a 16:9 laptop monitor. I burn a lot of 16:9 videos to SVCD and I play them with Mplayer.

Now, since I want my disks to play in my standalone DVD player attached to the TV, I have to encode them as letterboxed 4:3 (i.e. the video is in 4:3 aspect ratio, but includes top and bottom black borders in the video itself, so the actual movie within the 4:3 video is in 16:9). This makes sure I can see the whole content (no pan and scan) on my TV and my desktop PC.

If I was just coding them for use on my desktop, I would encode them as 16:9 SVCDs, but these aren't supported by standalone DVD players.

Now, my problem is this: I also take a lot of train trips and I want to watch these videos on the train as well, however, since the video file is encoded as 4:3 and my laptop screen is 16:9, the actual video content on these disks ends up looking flattened when I play it fullscreen in Mplayer. Is there anyway to tell Mplayer to expand the 4:3 letterboxed video so that the whole screen is taken up by the actual 16:9 content within the 4:3 letterboxed video?

Thanks!
 
Old 05-16-2006, 11:08 AM   #2
anon237
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Hi,

Maybe this will help (from mplayer manpage):

-aspect <ratio>
Override movie aspect ratio. It is autodetected for MPEG files, but it cannot be done for most AVI files.

EXAMPLE:
-aspect 4:3 or -aspect 1.3333
-aspect 16:9 or -aspect 1.7777

Hope this helps.
 
Old 05-16-2006, 11:36 AM   #3
JoeDuncan
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Thanks for your reply, but I just found the the answer.

SVCD files encode the DAR (digital aspect ratio) into the mpeg file itself, so "-aspect" just overrides that.

Using "-aspect 4:3" does nothing, because that's what's encoded in the mpeg file anyway.

Using "-aspect 16:9" just squishes the video even further (it makes it even wider rather than taller).

What I needed to do was use the following command line option:

-vf crop=480:360:0:60

This tells mplayer to crop the video down to 480x360 and position the top left corner of the crop box at 0,60 on the original image.

This works because SVCD video files have a resolution of 480x480, but they get stretched to cover their assigned DAR (so a 4:3 DAR coded SVCD is stretched horizontally to cover 640x480 and a 16:9 DAR coded SVCD is stretched horizontally to cover 853x480 - but 16:9 DAR SVCDs are not supported on standalone DVD players).

When you letterbox a 16:9 video into a 4:3 DAR SVCD, the actual video content is only contained in 480x360 of the SVCD video file, the top and bottom 60 pixels are filled in with black.

So, what happens with the command line option I indicated is first the top and bottom 60 pixels are cropped off, making the video 480x360. Then, since the DAR is 4:3, the 480 horizontal resolution is stretched to cover 640 pixels, meaning the output video is now 640x360 - which is an actual 16:9 aspect ratio and fills the whole screen on my laptop when I use full screen mode! Yay!
 
  


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