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 decoding method using a processor, the method comprising:
accessing, by the processor, 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 referenceable frames,
wherein at least one such motion vector is scaled by a frame scale fraction, and
wherein at least two or more of the referenceable frames are in prior display order.
2. The method of claim 1 , wherein one of the referenceable frames is a predicted frame.
3. The method of claim 1 , wherein the frame scale fraction is greater than 1.
4. The method of claim 1 , wherein the frame scale fraction is a negative fraction.
5. The method of claim 1 , wherein the frame scale fraction comprises a numerator and a denominator, wherein the numerator of the frame scale fraction is proportional to a first frame distance from the bidirectional predicted frame to one of the referenceable frames.
6. The method of claim 5 , wherein the denominator of the frame scale fraction is proportional to a second frame distance between a first referenceable frame and a second referenaceable frame.