[FFmpeg-user] show watermark at the beginning of the video

[Alex Vasilenko]

> On 3/19/13, Alex Vasilenko <aa.vasilenko at gmail.com (mailto:aa.vasilenko at gmail.com)> wrote:
> > Hi all ,
> > 
> > Need to add watermark for first 3 seconds the video using ffmpeg. Here's
> > what I got right now:
> > 
> > ffmpeg -y -i '255871.mov' -qscale:v 0 -qscale:a 0 -vf '[in] transpose=1
> > [out];movie=watermark.png , select=lte(t\,3) [bg]; [out][bg]
> > overlay=x=20:y=main_h-60 [out]' output.mp4
> > 
> > It rotates video to the right and adds watermark at the bottom of the video
> > for first 3 seconds. The problem is watermark is visible during the whole
> > video.
> > 
> > Thought that select doesn't work at all. Tried following command
> > 
> > ffmpeg -y -i '255871.mov' -qscale:v 0 -qscale:a 0 -vf '[in] transpose=1
> > [out];movie=watermark.png , select=0 [bg]; [out][bg]
> > overlay=x=20:y=main_h-60 [out]' output.mp4
> > 
> 
> 
> watermark.png is single frame, so select always pick it,
> yes it it little strange but that is how overlay filter works.
> 
> Instead you could use blend filter, you first would need to pad watermark.png
> with pad filter to same size as input and pad it with black color and than set
> some complicated expression for blend filter.
> 
> 

Wow, that's far more complicated. But how does select filter work? Shouldn't it filter out watermark frame after 3 seconds of video?
> 
> This is too much complicated and IIRC there is ongoing work on making
> real scripting
> with libavfilter available.
> 
> 

Good news! :) 
> 
> > 
> > Watermark is not visible. This is correct and proves that select filter
> > works as expected. As I understand this is how ffmpeg works: it leaves last
> > frame of the shortest video visible.
> > 
> > How can I force ffmpeg to discard show watermark after N seconds?
> > 
> > Cross posted this question on SO:
> > http://stackoverflow.com/questions/15482644/show-watermark-at-the-beginning-of-the-video
> > 
> > 
> > Thanks,
> > --
> > Alex Vasilenko
> > 
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> > 
> 
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