How does the value of alpha channel affect the video ?

    Cheng Chien-Wen
    Apr 04 2008 | 4:03 pm
    I feel confused about alpha channel and the way jit.alphablend works.
    I tried to make a patch to see if the value of alpha channel really affects the video, but it does not seem to change anything.
    My way of doing it is to multiply alpha channel value with jit.op. I found that ｗhatever the multiplier value is, the resulted video is the same. Does this mean that changing the alpha channel value does not affect the resulted video ?
    Could anyone explain it ? Thanks.
    The following is the testing patch I made:
    • Marcos
      Apr 04 2008 | 4:30 pm
      I think it only makes a difference if there an element in the background, such as another video or perhaps an image. Alpha channel shouldn't affect just a single video or a single image, bcs there is nothing to see behind it. Maybe I am wrong.
    • Rob Ramirez
      Apr 04 2008 | 8:32 pm
      try this, and see if you still have questions...