Hey all,
After seeing tom's nice work online I realized I've been missing something in Gem. He is using alpha channels in video using Gem on winXP!!
This is a feature I've been hoping for for years. (in 2003 when creating Oracle I had to use still-images and pix_masks to create anti-aliased text on a video background.)
So being inspired by Tom I gave a real effort to alpha channels on OSX.
The GREAT news(!) is that I can load images with pix_image (tiffs) with intact alpha channels! It is truely a beutiful thing to see!
So after this success I went to video. I tried three cases (it seems aftereffects only exports videos with alpha channels compressed with TIFF, TARGA, and PNG. So for fun I exported alpha channel videos and tried to load them in Gem. Every single one loads fine according to the pix_film and pix_movie output, BUT only shows a green square in the render. Looking further I realized that my Gem 090 does not load any quicktime movies compressed with TARGA, TIFF or PNG.
Could someone give this a try on thier OSX machines? I did not try all the codecs, but I know DV, cinepack, photojpeg and sorenson certainly work. I think I reported the same trouble with the animation codec a while back.
I don't care much for Gem supporting all codecs personally, but it would be very nice If we have one codec on OSX that supported alpha channels working (TARGA, TIFF or PNG) the latter two being my preference.
This also brings up the issue of "similar" functionality working on all platforms. In theory we should be able to load alpha channels from TIFF images on all platforms, as well as loading Quicktime movies using the TIFF codec with alpha channels. :)
Thank you Gem developers!!!
b.
Thomas Ouellet Fredericks wrote:
I can correct most of the stuff but I do not understand the error :
MPEG3: unsupported!
I made the mvoies with quicktime pro 6.3. They are actually TGA image sequences, millions+ of colors. What alpha format does quiktime for linux support?
The movies are read with [pix_movie] followed by an [alpha] box.
Tom
On Wed, 16 Mar 2005 11:13:44 +0100, Frank Barknecht fbar@footils.org wrote:
Hallo Thomas, Thomas Ouellet Fredericks hat gesagt: // Thomas Ouellet Fredericks wrote:
On Tue, 15 Mar 2005 23:29:09 +0100, Frank Barknecht fbar@footils.org wrote:
Krzysztof Czaja hat gesagt: // Krzysztof Czaja wrote:
Could you please send me a print-out of the errors, I will correct the patch.
I attached all error messages until the Gem window appears. I did look around a bit in your patch already, but I could find dashed objects. However I surely haven looked in every patch yet. ;)
Ciao
Frank Barknecht _ ______footils.org__
_ __latest track: "scans" _ http://footils.org/cms/show/41
On Mar 16, 2005, at 5:05 PM, B. Bogart wrote:
After seeing tom's nice work online I realized I've been missing something in Gem. He is using alpha channels in video using Gem on winXP!!
...yeh, nice fish...
So after this success I went to video. I tried three cases (it seems aftereffects only exports videos with alpha channels compressed with TIFF, TARGA, and PNG. So for fun I exported alpha channel videos and tried to load them in Gem. Every single one loads fine according to the pix_film and pix_movie output, BUT only shows a green square in the render. Looking further I realized that my Gem 090 does not load any quicktime movies compressed with TARGA, TIFF or PNG.
...um, I think you're overlooking the obvious: green screens == yuv processing! So obviously there are no alpha channels (unless you use the gpu alpha blending, like [blend< )...remember, yuv is gem's "native" colorspace on osx, but not on the other platforms...in other words, you should be in alpha heaven with the above films if you send [colorspace RGBA< to [pix_film] or [pix_movie] before loading the film...
hth, james
ps: otoh, you could always add [pix_rgba] after [pix_film], but this will be sloooow...but not for too much longer, as I've been altivec'ing the color conversions :-)
Indeed nice fish...
Comments inline
james tittle wrote:
On Mar 16, 2005, at 5:05 PM, B. Bogart wrote:
...um, I think you're overlooking the obvious: green screens == yuv processing! So obviously there are no alpha channels (unless you use the gpu alpha blending, like [blend< )...remember, yuv is gem's "native" colorspace on osx, but not on the other platforms...in other words, you should be in alpha heaven with the above films if you send [colorspace RGBA< to [pix_film] or [pix_movie] before loading the film...
That indeed did the trick, both TGA and TIFF work great. :) I apologize for asking for an existing feature for so long, but indeed things were not working very well for alpha channels in Linux when I needed this functionality and got fixated on it!
Is there some fusion of YUV processing with RGBA? YUV+A? Alpha channels are really handy, but it seems that the best performance would be to use YUV to get the performance out of the RGB part of the image and keep the alpha channel. (maybe the alpha channel could be compressed similarly to the Luminance channel in YUV.) Just thinking aloud.
I'm really looking forward to the fast colour-space convertions!
thanks Jamie for all your support.
It would be really great to get you guys up here to do a serious masterclass in Gem.
Oh and I've attached my old "dynamics" pmpd patch (compatible with the stable pmpd release) using nice drop-shadow bitmaps instead of the old vector ones.
B>
hth, james
ps: otoh, you could always add [pix_rgba] after [pix_film], but this will be sloooow...but not for too much longer, as I've been altivec'ing the color conversions :-)
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