[MPlayer-users] Having problems ripping a telecine dvd [León:the professional Director's cut]

D Richard Felker III dalias at aerifal.cx
Fri May 9 02:51:39 CEST 2003

On Thu, May 08, 2003 at 06:25:11PM -0500, Jonathan Rogers wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> D Richard Felker III wrote:
> >Second, 16:9 is the aspect ratio before cropping. You need to crop off
> >the black borders or encoding quality will SEVERELY suffer. Read
> >DOCS/tech/encoding-tips.txt for a good overview of all the issues
> >involved, and remember, making a good encoding is a process that
> >requires a lot of care, attention, and willingness to learn, not an
> >automated "press-the-green-button-and-it-goes" thing.
> I had to think about the aspect ratio for a while before I figured out 
> how to get it right. The formula I use is:
> encoded_ar = (uncropped_ar * cropped_ar) / display_ar
> Where:
> encoded_ar := the ratio which you supply to lavc or MPlayer
> uncropped_ar := ratio of the DVD frame, 1.5 (720/480) for NTSC
> cropped_ar := ratio of the DVD frame after removing black areas
> display_ar := ratio DVD is supposed to display at, typically 16/9 or 4/3
> For one DVD I did recently, uncropped_ar=720/480=1.5, 
> cropped_ar=716/258=2, and display_ar=16/9=1.7778, so encoded_ar=2.37. 
> The technique I use is to scale the frame (with -sws 2 for high quality) 
> to something close to the encoded_ar, and set aspect=encoded_ar as well. 
> That way, it will be displayed perfectly by MPlayer, and acceptably by 
> other players.
> As for the "press-the-green-button-and-it-goes" issue, there are tools 
> which do most of the grunt work for you, but mencoder certainly doesn't. 
> I used dvd::rip <URL:http://exit1.org/dvdrip/> for a while, but mencoder 
> seems to have some advantages over transcode. There are also 
> <URL:http://acidrip.thirtythreeandathird.net/>, 
> <URL:http://sourceforge.net/projects/kmencoder/> and 
> <URL:http://gmencoder.sourceforge.net/>, but I haven't tried them yet. 
> As with anything, if you want maximum control, you must understand the 
> details, but if you don't want to spend as much time, there are tools to 
> deal with the details.

Yes, well regarding the details of picking the right aspect after
cropping...if you get latest mplayer CVS, you can just use -lavcopts
autoaspect and forget about having to do any computations. :))

But you still need to make sure you're fully cropping the black
borders and any artifacts around the edges of the picture, or encoding
quality will severely suffer. Stuff like this is hard to automate.


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