Video Playback Time Remapping via Keyframe Speed Control
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Solution Overview
Problem
Existing digital video editing systems lack an intuitive and precise method for controlling video playback rate transitions, often resulting in undesired changes in playback rate across video sequences and difficulty in specifying transition regions accurately.
Innovation Solution
A digital video editing system with a user interface that allows users to define keyframe elements, including a begin element, end element, and intermediate time element, to generate a time transition function that maintains constant speeds at the begin and end elements while smoothly transitioning between them, using a single or dual control handles for input, and employing exponential weighting for non-linear transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional speed/velocity graph with control points and Bezier curves is used for time remapping, then playback speed can be controlled at different points, but it is difficult to precisely specify transition regions and control the exact timing of speed changes
Solution Approach 1:
The patent changes the fundamental parameters used for time remapping from continuous Bezier curves defined by control points to discrete keyframes with explicit time and speed values. Each keyframe represents a specific moment in time with a defined playback speed, allowing precise specification of transition regions through time values rather than through curve interpolation. This parameter change enables exact control over when speed changes occur and for how long they persist.
2Reliability
If multiple control points with Bezier curves are used to define playback speed, then speed transitions can be created, but undesired changes in playback rate may occur in regions outside the intended transition areas
Solution Approach 1:
The patent segments the video timeline into distinct regions defined by keyframes, where each keyframe marks a specific transition point. The regions between keyframes have uniform playback speeds, creating clearly separated segments rather than continuous variable speed regions. This segmentation prevents undesired speed changes from propagating across the entire sequence, as each segment's speed is independently controlled by its bounding keyframes.
Solution Approach 2:
The patent applies local quality by allowing different playback speeds to be assigned to different time segments defined by keyframes. Each keyframe region can have its own specific speed value, enabling precise local control over where and how speed transitions occur. This local control ensures that speed changes are confined to specific portions of the video sequence rather than affecting the entire sequence uniformly.
3Stability of the object's composition
If Bezier-like curves are used to dictate playback speed between control points, then smooth transitions can be achieved, but it is difficult to maintain constant speed in regions leading into and out of transition areas
Solution Approach 1:
The patent applies preliminary action by establishing keyframes at specific time points with predetermined speed values before rendering the video sequence. The keyframes define the exact moments where speed changes should occur, and the regions between keyframes are assigned constant speeds in advance. This preliminary definition of speed regions ensures that constant speed is maintained in areas leading into and out of transitions, as the constant speed regions are explicitly defined by the keyframe boundaries rather than being derived from curve interpolation.
Data Source
AI summary
The present disclosure includes systems and techniques relating to generating transitions for remapping video playback time. The subject matter described in this specification can be embodied in a method that includes providing a digital video editing user interface that includes a variable rate speed control configured to define associated keyframe elements including a begin element, an end element and an intermediate time element; receiving input defining at least one of the keyframe elements in relation to a sequence of digital video; and generating a time transition function for remapping playback time of the video based on the input, wherein the time transition function maintains predefined speed for video frames leading into the begin element, maintains predefined speed for video frames leading away from the end element, and changes video speed from a begin speed value to an end speed value in accordance with one or more intermediate time element values.