[FFmpeg-user] sequence with alpha over a still renders alpha incorrectly

[Lou]

On Thu, Aug 28, 2014, at 08:17 PM, Ehren Addis wrote:
> I'm trying to put a png sequence with an embeded alpha over a still 
> image with burned in timecode.  The following has been had from 
> everything I see on the web (with the exception of using -shortest that 
> never worked).  This renders, but the alpha channel renders in a strange 
> banded sort of way.  A smooth gradation comes out like lots of 
> transparent stripes that move around.  I'm starting to suspect this 
> isn't the way the current ffmpeg would do it.  Can anyone point me in 
> the right direction for the proper syntax?
> 
> ffmpeg -loop 1 -r 29.97 -i background.jpg -r 29.97 -i 
> foregroundsequence%05d.png -filter_complex "overlay, 
> drawtext=fontfile=ARIAL.ttf: timecode='00\:00\:00\:00': r=29.97: 
> x=(w-tw)/2: y=h-(1*1h): fontsize=32: fontcolor=white: box=1: 
> boxcolor=0x00000099" -r 29.97 -t %dur% -vcodec prores -profile:v 2 -y 
> output.mov
> 
> I had to use -t instead of -shortest to get this to not encode 
> indefinitely, contrary to examples floating on the web.
> 
> Thanks!

Please include the complete ffmpeg console output. Providing one of the
foregroundsequence*.png images could be helpful too.