Embedding frame masks in a video stream

Techniques are described for efficiently embedding frame masks in a video stream. In some solutions, a computer implemented method includes operations for encoding a frame of video data comprising an array of pixels to generate an encoded video frame, and transmitting the encoded video frame to a video decoder. The array of pixels include foreground pixels and background pixels. The foreground pixels have respective first chroma component values which are bounded within a first chroma component range. Encoding the frame of video data can include converting the first chroma component values of the foreground pixels to second chroma component values by applying a mapping function. The second chroma component values are bounded within a second chroma component range. The second chroma component range is shifted or compressed from the first chroma component range.