B-prediction
ISO/IEC MPEG-1 bi-directional prediction reproduced with the original np1/np2/np3 frames and faithful block-matching logic.
Sequence setup
Frames n−1, n, and n+1 act as the fixed reference inputs for the matching and residual workflow.
Prediction logic
- Forward/Backward: Motion search compares the current frame against the previous or future frame to minimize the sum of absolute differences.
- Bi-directional: A dual search selects the best block from either neighbor and marks whether the past (red) or future (blue) frame was chosen.
- Entropy readout: Residual entropy follows the following: values are normalized to 256 bins across the −1…1 range.
Video sequence from provided frames
Frame n−1
Frame n
Frame n+1
Prediction error maps (block size 8×8, search range ±32 pixels)
Residuals follow the following block search with grayscale differences centered at 0 and remapped to 0…255 for display.
Bi-directional residual
Entropy: – bit/pixel
From previous frame
Entropy: – bit/pixel
From subsequent frame
Entropy: – bit/pixel
Residual histograms
Bins span 256 uniformly spaced levels between −1 and 1
Bi-directional
From previous
From subsequent
Reference support for each block
Blocks predicted from the previous frame are tinted warm; those matched to the subsequent frame are tinted cool.
Block from previous frame
Block from subsequent frame