is possible to save a video with a trasparent background?
i mean i save in example a text like HELLO moving around the screen and want to send to a friend that need to work with this video, but there will be a background that will cover his project (its just an example)
so is there a way to save a video without a background? just the moving text? so this teoric friend can use my animation on his video just watching the text HELLO instead of HELLO with the background etc
Transparency doesn't exist outside programs that support it. Even if your footage may be saved with an Alpha channel using a suitable CoDec, juts playing it back in any player won't make it transparent. It's all a matter of interpretation and the programs handling it. So no, what you want will never work. If your friend wants to import the footage back into his AE or Premiere, then that's anotehr matter. Simply use a render setting and output format that creates Alpha then.
how can i create an alpha output?
can you guide me?
or in example, if this text is written on a black background i can use fusion method and set ADD right? but why dont' work in example with a white background?
Add your composition to the render queue (either Control+M, or click "Composition" on the top menu bar and select "Add to render queue)
There is where you will find the options to change the ouput module settings, and the location.
Notice the yellow word "Lossless" on the bottom left of the screenshot? click the down arrow next to it (or just the word itself)
It might be a good idea to get some starting tips here:
or even here
The second link has a section at the bottom dealing with renders specifically. Bookmark these links and read them all the time. I have been using After Effects for a while now, and yet i return to these links so often, I am afraid the image might burn into my monitor!