Alpha Channel

[JEB]

Hi Folks,

I wonder if anybody can help me?

I wish to create an effect within a title slide of grass in the foreground, sky in the background and a title moving up between the grass and sky. I know how to do this using a .png of the grass in the foreground - however I have identified and downloaded a bit of 1920x1080 video on Vimeo that states - "the video has an alpha channel so you can easily add this in front of your other content". To the uninitiated like me this sounds like a video equivalent of a .png and indeed it looks like that in that the grass moves in front of a checkered background like PS.

I've no idea what an alpha channel is nor how this could be utilised in PTE. I have imported the video into PTE and it plays but will not permit my sky image behind it to be seen as I had hoped.

Any ideas?

Cheers

John

[PGA]

John,

Like you I do not understand the details of "alpha channel". Perhaps you should try using this video file as the mask file within a mask container. I mean in place of the black and white mask.

regards,

Peter

[Guest Yachtsman1]

Hi John

I've been doing quite a few shows in the last 2 or 3 months using similar effects to what you describe. How did you add your image to the video, as a stand alone image or a child linked to the video?

Eric

Yachtsman1.

[Lin Evans]

Hi John,

At the present time, PTE can only use an alpha channel video as implemented in an RGBA avi alpha channel video. The alpha channel feature can be found in a number of different formats including Flash flv, Apple's .mov, etc., but these other formats are not yet amenable to PTE.

There are several application software programs which can be used to output text and effects including the alpha channel and use an appropriate codec to allow the creation of this avi format which works perfectly with PTE. Among these are two which I use: ParticleIllusion and BluffTitler. There is a free codec which you can download and use to create your video called HuffyUV 2.2.0 which supports alpha channel. I use this codec with ParticleIllusion and it is defaulted in BluffTitler for creating my avi videos with alpha channel.

Supporting other alpha channel formats such as .mov and .flv is on the table for development with PTE but is not yet supported. To use an alpha channel avi right now with PTE you need to create your alpha channel video in avi format and I would suggest using the HuffyUV 2.2.0 codec.

Many of my special effects have been created using this feature.

In the new Slideshow Club demo's section, you can see the use of the avi alpha channel video in my flaming astroid which goes behind the icosahedron with multiple videos and the in front of the moon here:

http://www.slideshow...mation-example/

I created this alpha channel video with ParticleIllusions using the HuffyUV 2.2.0 codec...

Here's a link to an MP4 h.264 video using both ParticleIllusions and BluffTitler as a demo which I created long ago as a demo of PTE's alpha channel video capability:

http://www.lin-evans.org/demo/testblufftitleralpha.zip

Best regards,

Lin

[Ken Cox]

http://blogs.adobe.com/premierepro/2010/07/exporting_video_with_an_alpha.html

ken

[JEB]

Thanks all for your replies.

Peter,

I have tried your suggestion,however, though I get the sky image to appear the checkerboard of the video also appears over it or through it, not sure which. I have tried using the video as the mask and the sky as the mask but not getting the result I was hoping for.

Erik

This was my first thought and tried both but whichever is on top of the stack is displayed.

Lin,

You'll need to give me time to get my brain round this I'm afraid. I have Camtasia2 so may play around with that. Would be interested to hear if that in your opinion is a no no!

Ken

Not had a look at your URL yet.

Cheers

John

[Lin Evans]

Hi John,

I don't have Camtasia 2 so I'm not certain whether or not it can export video as AVI with alpha channel, but if it can, then you can create your alpha channel video that way. Just download and install the free Huffyuv 2.2.0 codec and use it when creating your RGBA avi with alpha channel.

http://www.free-code...oad/huffyuv.htm

Essentially, the video with alpha channel works for video just like a png with transparency works for a still image. The actual creation of the video must be supported by the software being used so that the background is subtracted. Generally, when creating text you choose a solid color background of a color not found in the text itself. This color is then subtracted from the video by the software and when the file is output as an RGBA avi file, the background becomes transparent allowing whatever lies on the layer beneath to show through all areas where there is no text.

Should it be the case that Camtasia 2 can't output RGBA avi video then I would strongly suggest downloading at least the demo of BluffTitler to try. BluffTitler is not expensive and is very powerful. ParticleIllusion SE which I use is no longer available and the pro version which is now available is prohibitively expensive unless you have a serious need for it ($389.00 USD). WonderShare, the developers of ParticleIllusion were bought out by GenArts and the less expensive version of ParticleIllusions was dropped. BluffTitler, on the other hand, is only @ $30 for the easy and @ $50 for the pro version. Highly recommended.

If you download the above Huffyuv codec from the link, and go to the BluffTitler page here:

http://www.outerspac...re.com/buy.html

You can download a free trial of BluffTitler which will let you make RGBA avi videos and test them with PTE. They will have "Demo" written on them, but you can easily make a decision whether this is something you might want. Many of the available alpha channel videos on the web are not RGBA avi format so they are not amenable with PTE. The majority of them are probably .mov or FLV format which PTE will support in the future, but not at the present time.

Best regards,

Lin

[JEB]

Hi all,

Thank you for your input, particularly to you Lin for taking so much time to TRY to educate me.

I've come to the conclusion that I don't want to invest more time on what looked like a good idea at the time. Furthermore, being a true Scotsman I don't want to invest money on what would be a ten second intro to my sequence.

I have learned something about alpha channels if only its not as simple as .png, so I'll reluctantly stick with what can make work and with what I was quite happy with before stumbling on that video!!

Thanks again,

John