[Mplayer-cvslog] CVS: 0_90/DOCS encoding.html,1.87,1.88

[Diego Biurrun CVS]

Update of /cvsroot/mplayer/0_90/DOCS
In directory mail:/var/tmp.root/cvs-serv10342

Modified Files:
	encoding.html 
Log Message:
Error in the aspect ratio calculation, plus typos and rewordings.
Noticed by Jason Tackaberry <tack at auc.ca>.


Index: encoding.html
===================================================================
RCS file: /cvsroot/mplayer/0_90/DOCS/encoding.html,v
retrieving revision 1.87
retrieving revision 1.88
diff -u -r1.87 -r1.88
--- encoding.html	29 Mar 2003 01:11:56 -0000	1.87
+++ encoding.html	4 May 2003 21:48:42 -0000	1.88
@@ -290,11 +290,11 @@
 <H2><A NAME="aspect">7.9 Preserving aspect ratio</A></H2>
 
 <P>DVDs and SVCDs (i.e. MPEG1/2) files contain an aspect ratio value,
-  which describes how should the player scale the video stream, so humans
+  which describes how the player should scale the video stream, so humans
   won't have egg heads (ex.: 480x480 + 4:3 = 640x480). However when encoding
   to AVI (DivX) files, you have be aware that AVI headers don't store this
   value. Rescaling the movie is disgusting and time consuming, there
-  must be a better feature!</P>
+  has to be a better way!</P>
 
 <P>There is.</P>
 
@@ -308,13 +308,18 @@
   other players will use the wrong aspect ratio.</P>
 
 <P>You seriously should crop the black bands over and below the movie image.
-  See the manpage about the usage of the <CODE>cropdetect</CODE> and
+  See the man page for the usage of the <CODE>cropdetect</CODE> and
   <CODE>crop</CODE> filters.</P>
 
 <H4>Usage:</H4>
 
 <P><CODE>$ mencoder sample-svcd.mpg -ovc lavc -lavcopts
-  vcodec=mpeg4:aspect=16.0/9.0 -vop crop=714:548:0:14 -oac copy -o output.avi</CODE></P>
+  vcodec=mpeg4:aspect=1.545 -vop crop=714:548:0:14 -oac copy -o output.avi</CODE></P>
+
+<P>Notice that we set the aspect ratio to 1.545 here. For a 16/9 DVD, the
+  video source is usually 720x480 which gets scaled to 854x480. So the correct
+  aspect ratio for the above cropped video, where the original is 16/9, is
+  714*(854/720)/548, or 1.545.</P>
 
 </BODY>
 </HTML>