Re: [Mlt-devel] Westley geometry question

[Dan D. <da...@de...>]

2009/3/22 Jonathan Thomas <jon...@gm...>:
> I'm attempting to use the "Composite" transition, but I can't seem to make
> the B track geometry grow to cover up the entire A track.  The B track seems
> to max out around 85% to 90% the size of the video, regardless of what
> X,Y,HxW I try.  Here is a snippet from the Westley XML:  Any suggestions?

There are a few factors. First, are the aspect ratios and resolution
of the clips in A and B the same? I suggest you first try with DV
files with matching aspect ratio and the appropriate corresponding
dv_... mlt profile. Secondly, the geometry, by default, defines a
bounding box, and the transition scales the B clip down to fit inside
the bounding box but does not scale the B clip over 100% of its
resolution. You can set fill=1 to make it scale up as well. Also, it
normalizes differences in aspect ratio to keep everything looking
correct, but you can set distort=1 to make it ignore aspect and
arbitrarily stretch the B video to the rectangle.

>      <transition in="120" out="210">
>           <property name="mlt_service">composite</property>
>           <property name="a_track">0</property>
>           <property name="b_track">1</property>
>           <property name="start">50%,50%:5%x5%:0</property>
>           <property name="end">0%,0%:100%x100%:100</property>
>           <property name="halign">centre</property>
>           <property name="valign">centre</property>
>      </transition>
>
> Also, I read in the documentation (i.e.
> http://www.mltframework.org/twiki/bin/view/MLT/Services), that the "start"
> and "end" properties have been depreciated.  Are there any examples using
> the "geometry" property to set the start, keys, and end properties?

>From your settings above:
geometry="0=50%,50%:5%x5%:0;-1=0%,0%:100%x100%:100"

It is a semicolon-delimited list of frame#=value where negative frame
# starts from the end of the transition. The maximum number of key
frames is the number of frames in the duration of the effect (no
sub-frame keyframes).

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