[MPlayer-users] Question about dvd resolution

[Catalin Muresan]

On Tue, Mar 11, 2003 at 10:55:48PM -0800, Shane Wegner wrote:
 > [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
 > On Mon, Mar 10, 2003 at 07:32:21PM +0000, Stephen Mollett wrote:
 > > On Monday 10 Mar 2003 18:38, Shane Wegner wrote:
 > > > In encoding a 16:9 DVD movie, I get the following from
 > > > mplayer when playing the actual dvd.
 > > > VIDEO:  MPEG2  720x480  (aspect 3)  29.97 fps  12250.0 kbps
 > > > ...
 > > > VO: [null] 720x480 => 854x480 Mpeg PES
 > > > Why the two resolutions?
 > > 
 > > The file is actually 720x480, but because it's 16:9, if you displayed it at 
 > > 720x480, it would come out 'squashed' horizontally on a 4:3-aspect monitor. 
 > > So it's scaled up to 854x480 to compensate.
 > 
 > Makes sense, thanks.
 > 
 > > > Now when I play the encoded avi with
 > > > lavc, the aspect ratio changes.
 > > > Movie-Aspect is 1.97:1 - prescaling to correct movie
 > > > aspect.
 > > > VO: [null] 720x366 => 720x366 Planar YV12
 > > > why has the aspect ratio changed?
 > > 
 > > The aspect ratio has changed because you've cropped the black bands and thus 
 > > changed the height. Aspect ratio for square pixels = (width/height):1
 > 
 > Hmm, I tried without the  cropping and get this.
 > 
 > VIDEO:  [DIVX]  720x480  24bpp  23.98 fps  -17179870.0 kbps
 > (-2097152.0 kbyte/s)
 > ...
 > VDec: vo config request - 720 x 480 (preferred csp: Planar
 > YV12)
 > VDec: using Planar YV12 as output csp (no 0)
 > Movie-Aspect is 1.50:1 - prescaling to correct movie
 > aspect.
 > VO: [null] 720x480 => 720x480 Planar YV12
 > 
 > So where the original aspect was 16:9, it appears to have
 > changed to 3:2.  Am I doing something wrong or is this just
 > the way it should be?

	You should either rescale Y so the aspect will be 2.33 (854/366)
which means rescale Y to 720/2.33 = 309, you should choose a close multiple
by 16, say 304. this way you don't have to use "aspect=", if you want to
have 720/366 resolution (with cropping) use -lavcopts aspect=2.33:(and the
other options you encode with).

	720/480 is 3:2 


 > 
 > Thx,
 > Shane
 > 
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-- 
 Catalin Muresan
 ASTRAL TELECOM
 Internet Department
 Technology Engineer