[mythtv-users] DVD rip aspect ratio off

Scott Alfter mythtv at salfter.dyndns.org
Thu Dec 7 18:10:27 UTC 2006

Alex Malinovich wrote:
> If I do a straight ISO rip of a DVD using mythdvd I get a normal rip
> preserving the aspect ratio of the DVD (in this case 16:9). However, if
> I actually transcode the rip to avi it ends up changing the aspect ratio
> to what looks like 4:3. I'm using the standard settings for mythdvd.
> Checking the mtd.log shows that the transcode cmd line is:
> 09:19:21: transcode command will be: transcode -i <myfilename> -g
> 720x480 -f 0,1 -M 2 -V -j 0,8,0,8 -y xvid -w 1618 -o <myfilename.avi>
> --print_status 20 --color 0
> I'm no expert here, but I don't think 720x480 is 16:9. That would be
> closer to 720x405 (if my math is right). So any ideas what I can do
> here?

Aspect ratio and resolution are unrelated.  All DVDs are encoded at either
720x480 or (occasionally) 352x480, but the video is then either stretched or
squished as needed to display with an aspect ratio of either 16:9 or 4:3.  On
playback, a 4:3 DVD might be scaled to 640x480 to make it look normal, while a
16:9 DVD might be scaled to 852x480.

The one time I tried ripping a DVD with MythDVD, ISTR running into an
aspect-ratio problem.  Since I had already figured out an alternate method
using DVD Decrypter (through Wine) and mplayer to rip DVDs, I've just kept
using that method instead.  Whether ripping to MPEG-4 (XviD) or to H.264, the
aspect ratio is preserved (and recalculated, in some instances) throughout the

Last week's Battlestar Galactica, for instance, got cropped from a 480x480 4:3
MPEG-2 recording to something like 464x360 (to get rid of letterboxing and the
thin black bars on the sides) and encoded to H.264 (with AAC audio instead of
MPEG layer-2 audio).  On my widescreen TV, the reencoded file fills the screen
without needing to do anything special.  On a 4:3 TV, the player will letterbox
it on-the-fly.  When I archive the show to DVD, 464x360 will be scaled to
720x480 and it'll be flagged as 16:9 (of course, it'll be reencoded to MPEG-2
from the original MPEG-2 file, and the audio will be transcoded to AC3).

 / v \ Scott Alfter
(IIGS( http://alfter.us/            Top-posting!
 \_^_/ rm -rf /bin/laden            >What's the most annoying thing on Usenet?

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