What is an embedded alpha channel?
An embedded alpha channel can be though of as a selection mask that is associated with each frame of a movie file. Each movie frame consists of 3 RGB image channels and 1 alpha channel for the mask associated with the frame. Each pixel in the alpha channel is used to define percent coverage for the associated RGB pixels values. An alpha value of 0 means 0% coverage, so the pixel RGB values are totally masked. An alpha value of 255 means 100% coverage, so the pixel RGB values are fully displayed. In between alpha values will define partial transparency for the pixel. The ARGB frame and it’s associated image channels will probably be additionally compressed by whatever compression type (referred to as a codec) you have chosen for your movie file output. Keep in mind that not all compression types support embedded alpha channels. So if you are interested in including one in your generated movie file you need to choose a codec type that supports embedded alpha. This is discussed in more de
