Frame-Rate Conversion via Presentation Time Stamps
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Solution Overview
Problem
Modern TVs face challenges in displaying content with varying frame rates, such as 24, 25, or 30 fps, on higher frame rate displays like 60/50 fps TVs, leading to issues like motion blur and judder due to misclassification of cadences and reliance on fallback modes, which can result in undesirable visual disturbances.
Innovation Solution
A method for generating presentation time stamps (PTS) that synchronizes new frames with their capture time stamps and uses average differences to ensure equidistant frame distribution, applicable to various cadences, including hybrid content, to reduce visible switching artefacts and provide a smooth transition between different patterns, thereby enabling motion-compensated frame-rate conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple frame repetition pull-down is used for frame-rate conversion, then device complexity is reduced and implementation becomes cheaper, but picture quality deteriorates with motion blur and judder
Solution Approach 1:
The patent changes the temporal parameters of frame presentation by calculating and applying presentation time stamps (PTS) that account for the original capture time stamps (CTS) and the target frame rate. This transforms the simple repetition approach into a temporally-adjusted approach, improving motion representation without requiring complex hardware modifications.
Solution Approach 2:
The patent introduces dynamic frame spacing by calculating variable PTS values based on the original cadence pattern and target frame rate. Instead of fixed interval repetition, the system dynamically determines when to present each frame to achieve smooth motion at the target frame rate, reducing judder and motion blur.
2Ease of manufacture
If motion-compensated FRC is implemented to improve picture quality, then motion representation improves, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical motion compensation algorithms with a temporal stamp-based approach. Instead of performing computationally intensive motion estimation and vector calculation, the system uses PTS/CTS timestamp manipulation to achieve similar motion representation benefits, significantly reducing processing complexity while maintaining picture quality.
Solution Approach 2:
The patent introduces presentation time stamps (PTS) as an intermediary mechanism between the original capture time stamps (CTS) and the final frame presentation. This intermediary layer simplifies the conversion process by providing a straightforward temporal mapping relationship, avoiding the need for complex real-time motion analysis.
3Adaptability or versatility
If cadence detection is used to identify film vs video content, then appropriate FRC processing can be applied, but false classification leads to visual disturbances
Solution Approach 1:
The patent creates a universal FRC method that works for both film and video cadences without requiring accurate classification. The PTS calculation formula adapts to different cadence patterns automatically, making the system multi-functional and eliminating the harmful effects of false classification while maintaining adaptability to various content types.
Solution Approach 2:
Instead of trying to correctly classify cadence to determine processing method, the patent inverts the approach by using a single processing method (PTS-based FRC) that automatically adapts to different cadences. This eliminates the classification step and its associated errors, while the method itself handles different content types appropriately.
4Device complexity
If hybrid content with multiple cadences is processed using a single FRC method, then processing simplicity is maintained, but visual quality deteriorates due to switching artefacts
Solution Approach 1:
The patent applies local quality adjustment by allowing different regions of hybrid content to be processed with their native cadence characteristics preserved through PTS calculation. Each frame's PTS is calculated based on its specific cadence pattern, enabling local adaptation without requiring complex region-based processing, thus maintaining both simplicity and visual quality.
Data Source
AI summary
A method of generating presentation time stamps, PTSs, for motion-compensated frame-rate conversion of a sequence of frames. In one aspect, the method comprises for each new frame: determining an average difference between the capture time-stamps of recent consecutive new frames; and generating the PTS based on the capture time-stamp of a previous new frame and the average difference. In another aspect, the method comprises detecting a first cadence and a second different cadence in the sequence of frames; and generating a PTS for each new frame defined by the first cadence, such that in each case the difference between the PTSs of consecutive new frames is intermediate between the true interval between those frames according to the first cadence and the true interval between them according to the second cadence.