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. An apparatus comprising a video bitstream stored on one or more non-transitory machine-readable media, the video bitstream characterized by:
square blocks of predicted and bidirectional predicted frames, wherein at least one square block of a bidirectional predicted frame is in a compressed format, and wherein the compressed format comprises:
a signal indicating an interpolative motion vector prediction mode for the at least one square block based on one or more referenceable frames;
a signal indicating a pixel interpolation mode using an unequal pixel weighting of one or more referenceable frames; and
two or more pixel weight values for the unequal pixel weighting.
2. The apparatus of claim 1 , wherein the pixel weight values comprise weights in a range of −1.0 to +2.0.
3. The apparatus of claim 1 , wherein the pixel weight values comprise at least one weight greater than +2.0.
4. The apparatus of claim 1 , wherein the at least one square block comprises a grouping of multiple discrete cosine transformed (DCT) blocks.
5. A decoding method using a decoder, the method comprising:
receiving a bitstream comprising a sequence of predicted and bidirectional predicted frames each comprising pixel values arranged in square blocks;
determining at least one square block within a bidirectional predicted frame using an interpolative motion vector prediction mode based on one or more motion vectors from two or more referenceable frames, wherein the at least one square block is determined using an unequal weighting of pixel values corresponding to the two or more referenceable frames, and wherein the unequal weighting of the pixel values comprises weights received in the bitstream by the decoder.
6. The method of claim 5 , wherein the weighting of pixel values comprises weights in a range of −1.0 to +2.0.
7. The method of claim 5 , wherein the weighting of pixel values comprises a least one weight greater than +2.0.
8. The method of claim 5 , wherein the weighting of pixel values comprises a first weight that is less than zero and a second weight that is greater than +1.0.