[FFmpeg-soc] [PATCH] updated! vf_overlay alpha patch and watermarking using PNG with alpha

[Stefano Sabatini]

On date Tuesday 2009-12-01 00:57:59 +0100, Stefano Sabatini encoded:
> On date Tuesday 2009-12-01 00:50:50 +0100, Vitor Sessak encoded:
> > Artur Bodera wrote:
> >> For those that have given up on ffmpeg and +libavfilter -vhook debacle.
> >>
> >> Here's a "just add water" solution to all your trouble: transparent PNG's
> >> and watermarks in recent ffmpeg compilations.
> >>
> >> I'm attaching a working patch that will enable alpha-transparency in overlay
> >> filter. This, on the other hand, will let you use overlay filter to
> >> superimpose a video clip or transparent png watermark on another video. This
> >> has been tested with recent revisions of svn://
> >> svn.ffmpeg.org/soc/libavfilter rev. 5387 and ffmpeg rev. 19868 (16 Sep
> >> 2009). Compiled and running under both x86 and x86_64 on linux.
> >>
> >>
> >> Example 1 - insert transparent PNG watermark in bottom left corner of the
> >> video:
> >> -vfilters "movie=0:png:logo.png [wm];[in][wm] overlay=10:mainH-overlayH-10:1
> >> [out]"
> >>
> >> Notice the last parameter to overlay ":1" - this enables alpha blending.
> >>
> >>
> >> Example 2 - insert 2 different transparent PNG watermarks (second watermark
> >> on bottom right corner):
> >> -vfilters "movie=0:png:logo.png [wm];movie=0:png:logo2.png [awm];[in][wm]
> >> overlay=10:mainH-overlayH-10:1 [int];[int][awm]
> >> overlay=mainW-overlayW-10:mainH-overlayH-10:1 [out]"
> >>
> >> You could chain and add more overlays this way but the efficiency of such
> >> approach is yet to be tested.
> >>
> >>
> >> This should save you a lot of time and you can continue to use your favorite
> >> transcoder for web video publishing!
> >
> > While I normally oppose making non-committed code more complex, I think  
> > this feature is so often requested that it is worth the extra work in  
> > the future. Stefano, Michael, any strong opinion about this?
> 
> I'm fine with committing the patch to soc if tested, even better would
> be to try to push the filter to the main repo. Does someone want to
> volunteer for this?

I'll apply the patch soon as this feature is probably the most
requested for lavfi, then I'll work on a proper filter integration
when the lavfi test system will be ready (I hope within a month).

Regards.