[FFmpeg-user] Watermark and Text overlay at the same time?

[Clément Bœsch]

On Tue, Dec 30, 2014 at 11:05:18PM +0000, Carl Eugen Hoyos wrote:
> Les Irvin <lesirvin <at> gmail.com> writes:
> 
> > ffmpeg -r 1/4 -i img_%03d.jpg -i audio.mp3 -codec:a copy 
> > -c:v libx264 -vcodec png
> > -vf "movie=wm.png [wm]; [in][wm] overlay=10:main_h-overlay_h-10 [out]"
> > -shortest output.mp4
> > 
> > Now, I'm trying to add a text overlay as well:
> > 
> > -vf "[0:v]drawtext=fontfile=Average-Regular.ttf:text='TESTING';"
> 
> Please try to remove the following from your command line:
>  [out]" -vf "[0:v]
> And instead use "," or ";" (sorry, I always forget which 
> one to use).
> 

A,B simply means B filters what A sends out. A;B separate two different
context.

Example:

  [in] split=2 [a][b];

       [a] curves, edgedetect, hue [x];
       [b] scale, subtitles        [y];

       [x][y] overlay [out]

This means:

 - You have one input ("[in]"), which you split into 2: [a] and [b]
 - Then in another context: the frames that arrive at [a] will get pass
   through curves, then through edgedetect then through hue filter, and
   will go out into [x]
 - Then in another context: the frames that arrive at [b] will get scaled,
   then subtitles will be applied on them, and they will then be sent to
   [y]
 - Then in another context, all the frames arriving from [x] and [y] will
   be sent to the overlay filter, which will sent the result to "[out]"

Hope it clarifies things. They are really two completely different thing.

Now there is also a confusing syntactic sugar that allow you to somehow
avoid the "context switch" with ';' by using a comma well placed, but that
is advanced, and if you're confused by it, don't do that.

IIRC, it basically means the previous filtergraph is equivalent to:

  [in] split=2 [a][b];

       [b] scale, subtitles        [y];
       [a] curves, edgedetect, hue,

       [y] overlay [out]

... You just drop out a label. (untested, but that's something along these
lines)

[...]

-- 
Clément B.
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