Blend Layer

The blend parameter puts a color or an image over the picture, composited in one of the CSS blend modes set by blend-mode. It works the same way it does on images, so a single URL produces the same result on a video source and on an image.

Valid values are a color (RGB, ARGB, RRGGBB, AARRGGBB, or a CSS color name) or an image URL. A relative URL resolves against the source’s folder.

Alpha comes first in the hex forms. 80000000 is black at 50% opacity. 00000080 is not the same thing (its leading 00 is a fully transparent alpha), so it draws no visible layer.

?fm=mp4&blend=80000000&blend-mode=normal
?fm=mp4&blend=logo.png&blend-w=0.3&blend-align=bottom,right

Up to four layers stack: blend (or blend[0]) at the bottom, then blend[1] through blend[3]. A layer is drawn when it has a color or an image.

The b alias accepts a color only — it never fetches an image. Use the full blend= spelling for an image layer. Every parameter in this family also has a base64 twin, such as blend64.

A blend layer has no timeline. The same layer is drawn on every frame, and a GIF or video supplied as blend= draws only its first frame.