Hi, how do I apply this white alpha?

Hi everyone,

I've downloaded many clips before, and (in Sony Vegas, my editing choice) I simply select alpha channel "straight", under the properties of the video clip. And this gives me instant transparency on my past downloaded clips.

Well now I've just downloaded one, which does not appear to have an alpha channel, at least in the way I am used to. Instead it has the animation in the first half of the video, and the animation entirely in white, at the latter half of the video.

You can see it in this preview:

http://www.pond5.com/stock-footage/87337/blast-multiple-with-particles-pal.html

Can someone please let me know what I'm supposed to do with this?

At the moment I'm guessing: slice the file in half, match up the exact frames with the white half, and set the white half as a mask... I hope I'm wrong, because that sounds a lot less straight forward and less efficient than just having an existing alpha channel on the file!

Many thanks, I appreciate your help! Have a project due in soon, so need to apply this within a few days hopefully!

Hi Dpvardy,

Unfortunately, you are right -- you need to cut it in half (which you can do using timecode), sync the two sides up, and apply a track matte.

We encourage people to submit alpha channel clips using the Animation codec, with the alpha embedded, but there are some clips on the site which are done with the alpha channel appended at the end.

Hope that helps.... should be pretty fast once you get the workflow down.

Tom

Thanks for getting back to me Shedli...

If I could just ask something more...

see my screenshot here of the animation in my editor:
http://img186.imageshack.us/img186/9759/trackmatteez0.jpg

Should I have the white animation on a top layer, and the main one on a layer beneith? Because I've tried with different compositing modes, listed in the screen shot, even tried specifying alpha etc, and mask, but without any relative success. (I usually save off each frame as a transparent .png)

I can make a setting whereby I see through the white, to the layers beneith, thus I see the exposion animation. But my problem then is that when I save off the frame, there is no transparency, and black around the explosion. I'm a bit confused, is this because the top layer is solid black, around the white? Or is it because the top layer is transparent around the white, seeing through the explosion layer beneith, which also happens not to be transparent? ...And also i don't see a track matte setting from the list. (the uploaded screenshot shows what the options are.)

Many thanks. Always the same isn't it? Just when you need to get on with something, you go one step ahead (eg, find the right animation) and two steps back (have to learn a new way to actually use it). ...I'm using the explosion in a flash animation, swishmax, hence needing it as transparent png files.

If you're not having success, try using the composite mode "Screen" on the explosion part of the clip. "Screen" makes the black in your clip transparent. You may lose a little off the explosion, but still find the result acceptable.

thanks for the advice kel, i tried this and all combinations and couldn't seem to find a solution. Is there any change i could paypal you or someone $25 to buy (at $20) this animation and export the frames from from it as transparent .png? I've a feeling I'm not going to be able to find a solution easily, and i have such a big flash project to work on that is currently hindered by this compositing detour. hehe.

..and if yes, then prefereably in the highest, neatest most efficient method and quality. ...I could do a bad and rough job on it myself just with a black chroma key, euck. Hence the reason I looked for files on these websites with existing alpha channel.

easier yet, if you can recompile the animation with an alpha channel without losing any quality, and send it back, i can grab the frames from it myself :) But I've often had a problem losing quality with recompressions in the past, even dv codec rendered out as dv sees to loose clarity when I've tried.

We've gone ahead and generated a version of the clip with the alpha channel embedded, and sent you a download link via email. Drop us a line if you run into any problems with it.

Thanks Shedli, you did a fantastic job! I had alpha transparency within about 10 seconds after your modified download :))))

I shall definately be returning to Pond5 :) Although hopefully one day I'll have mastered applying that style of transparency myself. I did look around for a sony vegas tutorial on the matter, and have played around with masks etc in the past, but couldn't quite crack that one.

If you ever come across some definitive tutorials on applying transparency techniques for different programmes, which you think are good, you might want to add a sticky in the forums (if there isn't one already) for the compositing newbies.

I can dive back into my main project now... many thanks again.

Have you tried applying the effect called "Mask Generator" in Vegas? Then work with the luminance settings only. That will take just about anything on a baclk background and turn it into an alpha mask.