On Tue 10 Aug 2010 at 06:24:06 PM +0200, Stefano Sabatini wrote:
>On date Monday 2010-08-09 18:34:49 -0700, George Georgalis encoded:
>> Hi all -
>> 
>> new to this list but I used mplayer back in '03 for kiosks development
>> 
>> today I'm trying to use two avfilters, overlay and drawtext, but
>> it doesn't seem I can use both at once. will I need to encode
>> the video twice, once for each filter?
>
>Yes, this is a known limitation that we should be able to remove:
>https://roundup.ffmpeg.org/issue2040

that seems like a slightly different issue for me. not knowing
the internal details, I'm just guessing here, but if there are
multiple avfilters request isn't it a matter of pipelining the data
stream through sequential avfilter calls? I don't see the need to
generate multiple output descriptors?

But along that vein, the multitee might be a useful library for
creating multiple outputs

http://code.dogmap.org/fdtools/multitee/
http://cr.yp.to/software/multitee-3.0.shar.gz

>> also, was wondering if there is a way to draw scrolling text, like
>> a marquee along the bottom of video?
>
>Well you know, patches are welcome...

I was thinking about a convoluted invocation that used the
drawtext filter with different positional parameters for each
frame. but I'm kinda assuming this would require huge cpu
recourses and/or generate enormous output file sizes (invoking
ffmpeg once for each frame). Clearly the better way is to add a
function that makes the positional parameters depend on the frame
count. ...a bit outside of what I am allowed to spend my time on...

-George
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