Interpolation of video compression frames
Coding techniques for a video image compression system involve improving an image quality of a sequence of two or more bi-directionally predicted intermediate frames, where each of the frames includes multiple pixels. One method involves determining a brightness value of at least one pixel of each bi-directionally predicted intermediate frame in the sequence as an equal average of brightness values of pixels in non-bidirectionally predicted frames bracketing the sequence of bi-directionally predicted intermediate frames. The brightness values of the pixels in at least one of the non-bidirectionally predicted frames is converted from a non-linear representation.
1. A decoder having a sequence of predicted and bidirectional predicted frames each comprising pixel values arranged in macroblocks, wherein at least one macroblock within a bidirectional predicted frame is determined using direct mode prediction based on motion vectors from two or more predicted frames, and wherein at least one such motion vector is scaled by a frame scale fraction of less than −1 or greater than 1.
2. The decoder of claim 1 , wherein at least two of the predicted frames are both in a subsequent display order to the bidirectional predicted frame.
3. The decoder of claim 1 , wherein at least two of the predicted frames are both in a prior display order to the bidirectional predicted frame.
4. The decoder of claim 1 , wherein at least two such motion vectors are scaled by a frame scale fraction of less than −1 or greater than 1.
5. A method for video image compression including:
providing a sequence of predicted and bidirectional predicted frames each comprising pixel values arranged in macroblocks; and
determining at least one macroblock within a bidirectional predicted frame using direct mode prediction based on motion vectors from two or more predicted frames,
wherein such determining includes using an unequal weighting of pixel values corresponding to such two or more predicted frames, and
wherein the providing and determining are performed by a processor.
6. A video image compression system having:
a sequence of referenceable and bidirectional predicted frames each comprising pixel values arranged in macroblocks,
wherein at least one macroblock within a bidirectional predicted frame is determined using direct mode prediction based on motion vectors from two or more referenceable frames, and
wherein at least two of such referenceable frames are previous in display order to the bidirectional predicted frame.
7. The system of claim 6 , wherein at least one such motion vector is scaled by a frame scale fraction of less than −1 or greater than 1.