Video Playback Speed Control via Dynamic Frame Duration
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Solution Overview
Problem
Existing digital video sequence playback technologies face challenges in maintaining precise control over playing speed, particularly in trickmode, where quality criteria such as speed precision, display fluidity, and temporal distribution are often contradictory, leading to oscillation effects and inefficient resource management.
Innovation Solution
A method that attributes display durations to frames based on a set playing speed, selectively decodes and displays frames, and manages resources to ensure real-time speed control, prioritizing certain criteria to improve playback quality by adjusting display durations and frame selection based on available storage and treatment capacities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the decoder decodes all frames at frame frequency and transmits to display control device, then the decoding completeness is improved, but the playing speed control precision deteriorates due to counter-based control limitations
Solution Approach 1:
The patent changes the control parameter from discrete counter values to continuous display duration values. Each frame is assigned a specific display duration based on the desired playing speed, allowing precise speed control by adjusting the time parameter rather than relying on discrete frame counting and duplication mechanisms.
Solution Approach 2:
The patent implements dynamic frame display control where the display duration of each frame is adjusted dynamically according to the desired playing speed. This allows the system to adaptively control playback speed by varying the time each frame remains displayed, rather than using fixed counter-based control.
2Productivity
If the decoder goes into degraded mode and skips certain frames to make up delay, then the real-time playback capability is improved, but the display fluidity deteriorates due to non-uniform frame distribution
Solution Approach 1:
The patent performs preliminary calculation of display durations for all frames before playback, taking into account the desired playing speed and frame dependencies. This pre-planning ensures that when playback occurs, the system can maintain fluid display by following the pre-calculated timing schedule, avoiding the need for reactive frame skipping that causes oscillation.
Solution Approach 2:
The patent introduces a timing control mechanism that acts as an intermediary between the decoder and display control device. This timing controller assigns specific display durations to frames and manages the playback schedule, mediating between decoding speed and display requirements to maintain both real-time capability and display fluidity.
3Adaptability or versatility
If the playing speed is modified while frames are waiting to be played, then the speed adaptability is improved, but the speed control precision deteriorates because changes cannot be taken into consideration until frames are played
Solution Approach 1:
The patent implements dynamic recalculation of display durations when playing speed changes are detected. Instead of waiting for frames to be played before applying speed changes, the system dynamically adjusts the display duration assignments for pending frames based on new speed requirements, allowing immediate response to user input while maintaining precision through continuous parameter updates.
Data Source
AI summary
A method of playing a compressed digital video sequence, comprising steps comprising attributing to each frame a display duration determined as a function of a playing speed set point, and at each period of a frame synchronization signal: if a display duration cumulative value is equal to or greater than a threshold value corresponding to the period of the synchronization signal, playing a previously acquired decoded frame and decreasing the cumulative value of the threshold value; and if the present cumulative value is less than the threshold value, acquiring a new decoded frame and adding the display duration attributed to the newly acquired frame to the cumulative value, until the cumulative value is equal to or greater than the threshold value, playing a last decoded frame acquired and decreasing the cumulative value of the threshold value.