Frame-Rate Conversion Apparatus Using Motion-Compensated Interpolation
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Solution Overview
Problem
Existing frame-rate conversion methods for video sequences often result in loss of images or repeated display artifacts due to variable frame rates, particularly in mobile terminals and other systems where conditions like jitter and delayed data transmission occur.
Innovation Solution
A frame-rate conversion apparatus using a frame buffer and motion-compensated interpolation module that adjusts the emptying rate based on the filling level to maintain a constant output frame rate, preventing overflow and underflow, and interpolating images to maintain a consistent display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If frame-skipping operation is used when variable frame-rate is higher than constant frame-rate, then the frame-rate is reduced to match the constant rate, but temporal display artifacts are caused
Solution Approach 1:
The patent applies preliminary action by performing motion compensation and interpolation before frame skipping occurs. The apparatus prepares intermediate frames in advance using motion vectors from reference frames, so that when frames need to be skipped to match the constant frame-rate, the interpolated frames are already ready to be displayed, preventing temporal artifacts
Solution Approach 2:
The patent uses motion-compensated interpolation as an intermediary process between the variable frame-rate input and the constant frame-rate output. This intermediary generates synthetic frames that bridge the temporal gap between skipped frames, acting as a mediator that smooths the transition and eliminates display artifacts
2Speed
If frame-repetition operation is used when variable frame-rate is lower than constant frame-rate, then the frame-rate is increased to match the constant rate, but temporal display artifacts are caused
Solution Approach 1:
The patent applies preliminary action by pre-calculating motion vectors and preparing interpolated frames before the frame-repetition operation is needed. When the variable frame-rate is lower than the constant rate, the apparatus has already generated the necessary intermediate frames through motion compensation, so simple repetition of original frames is avoided
Solution Approach 2:
The motion-compensated interpolation serves as an intermediary that creates smooth transitions between frames at different rates. Instead of directly repeating input frames which causes artifacts, the intermediary interpolation process generates visually coherent intermediate states that maintain temporal consistency
3Productivity
If simple frame-skipping and frame-repetition methods are used for frame-rate conversion, then the conversion from variable to constant frame-rate is achieved, but image quality deteriorates due to loss of images and repeated display
Solution Approach 1:
The patent introduces motion-compensated interpolation as an intermediary process that preserves image quality during frame-rate conversion. This intermediary generates high-quality synthetic frames based on motion analysis, avoiding both the frame loss from skipping and the repetition artifacts from simple duplication, thereby maintaining manufacturing precision in the form of image quality
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the interpolation parameters based on motion vectors and scene complexity. By changing the interpolation parameters adaptively, the system maintains high image quality across different frame-rate conditions while preserving conversion efficiency
Data Source
AI summary
In an embodiment, a method for converting an input video sequence, comprising digital images organized in frames and operating at a variable frame-rate, into an output video sequence, operating at a pre-set constant frame-rate, storing the input video sequence temporarily and controlling fetching of images of said temporarily stored input video sequence. The method further includes controlling fetching of images from the temporarily stored input video sequence by adjusting an emptying rate to form an intermediate video sequence; and carrying out an operation of motion-compensated interpolation on the intermediate video sequence to form the output video sequence operating at a pre-set constant frame-rate, the emptying rate being adjusted as a function of a number of images of the input video sequence with variable frame-rate temporarily stored. An application is in the reproduction of video sequences in mobile terminals, with the capacity of audio-video conversation, for example for videoconferences.