Lets say I have a photoshop image of a flying bird over an alpha channel.
I imported this image into Vegas Pro 22 and created an animation of the bird moving from left to right through the entire screen. This is my first render/generation.
now I want a flock of birds and just reloaded this new render and added copies on different layers and starting at different times on my timeline. Let´s say now I have 3 birds flying. This is my second render/generation.
Again, I loaded this new render and again copies more two or three times as before, so now I have many more birds.
In my final render I realize that somehow there´s an undesired outline on every shape of every bird, like there´s something wrong with my alpha channel. No matter if it is unmatted or premultiplied the outline is there. Sometimes brighter, sometimes darker, whenever I try to fix it by applying a different alpha type.
is this due to image degradation after all those renders/generations?
I usually render to mov (Resolume Arena DXV) file format, but I guess this is not related to the codec.
Any input on this is appreciatted.
Thank you!

Paulo