[PD] Alpha+pix_film

info at thesaddj.com info at thesaddj.com
Mon Jan 26 11:26:53 CET 2009


i use RGBA then :)
thanks IOhannes for explainations, now i get it.

i had the same issue with different video formats including
all the movies that come with Gem, so maybe there might be a
bug for real...
please tell me if you need more infos about this..

Marco



----- Original Message Follows -----
From: IOhannes m zmoelnig <zmoelnig at iem.at>
To: info at thesaddj.com
Cc: pd-list at iem.at
Subject: Re: [PD] Alpha+pix_film
Date: Mon, 26 Jan 2009 11:13:18 +0100

> info at thesaddj.com wrote:
> > HI everybody,
> > thanks to all, i solved the issue. But is still not
> > clear to me what's happening.
> > I mixed the different suggestions you gave me (cause
> > independently no one was working) and i got this:
> > 
> > [gemhead]
> > |
> > [pix_film]/[colorspace RGB(
> > |
> > [pix_alpha]
> > |
> > [colorRGB]
> > |
> > [alpha]
> > |
> > [pix_texture]
> > |
> > [rectangle]
> > 
> > it looks a bit weird but it's working and my cpu is
> > drinking a coffee while i mix four videos of 160/200mb
> > each. but I'm really keen to understand where was my
> > problem... as Philippe said i have to send the
> > [colorspace RGB( message first and then load videos. 
> > [pix_alpha] seems to be the obj making the work done,
> but
> 
> well, [pix_alpha] will overwrite whatever alpha is in the
> channel. so if the original alpha is 0 (full transparency)
> , [pix_alpha] will  eventually raise this to 1 (full
> opacity), thus making your object not  disappear.
> 
> what bothers me a bit is the use of RGB rather than RGBA
> in the  colorspace message....
> 
> 
> > anyway i had to add [colorRGB] to be able to change
> > transparency. 
> 
> well, that was the original idea, wasn't it?
> 
> > @IOhannes: i'm on windows xp pro. do you think it could
> > be because of this?
> 
> don't know, it just makes it easier to debug...(e.g. on
> osx the default  colorspace is YUV, having no
> alpha-channel at all, which would make it  unlikely that
> each pixel would have an alpha of 0) which movie are you
> opening? an AVI, a QuickTime movie?
> 
> could you share it for testing purposes? or does it happen
> with the  example movies that come with Gem as well?
> 
> > what do you mean with video-importer?
> 
> i mean the actual backend that reads the file and passes
> the frame to  pix_film.
> e.g. the Gem code that accesses QuickTime/W32 or
> DirectShow or gmerlin. if the movie does not contain an
> alpha-channel, "somebody" has to  provide values for alpha
> when doing RGBA; there might be a bug there...
> 
> fgkafdrt,
> IOhannes
> 
> 
> [Attachment: smime.p7s]




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