Subtitle Display Priority Control in Variable Speed Video Reproduction
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Solution Overview
Problem
Existing subtitle display technologies face challenges in maintaining accurate and prioritized subtitle rendering during variable speed reproduction, particularly in digital video broadcasting, where timing and priority information management are complex.
Innovation Solution
The solution involves inserting original time stamps and subtitle display priority information into the header or payload of subtitle PES packets, allowing for precise control and prioritization during variable speed reproduction by aligning subtitle packets with video packets at random access points, ensuring only the highest priority subtitles are displayed when overlap occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If text-based transmission of subtitle information is used, then subtitle information can be transmitted with timing information, but font development according to resolution is required and processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-generating bitmap data for multiple resolutions during the subtitle information preparation phase. The transmitting device creates and transmits resolution-specific bitmap data in advance, so the reproducing device does not need to perform font development processing during playback. This resolves the contradiction by maintaining complete timing information while eliminating complex runtime font processing.
2Productivity
If variable speed reproduction processing is performed, then playback speed can be adjusted, but subtitle display timing becomes inaccurate and overlap issues occur
Solution Approach 1:
The patent applies parameter changes by modifying the timing parameters of subtitle display based on the actual playback speed. The reproducing device calculates adjusted display timing by applying the playback speed factor to the original timing information, ensuring subtitles are displayed at appropriate moments regardless of whether the video is played faster or slower than normal speed. This resolves the contradiction by maintaining timing accuracy while enabling speed adjustment.
Solution Approach 2:
The patent applies dynamics by making the subtitle display timing adaptive to the playback speed. Instead of using fixed timing, the system dynamically adjusts subtitle display timing based on the actual reproduction rate. This allows the subtitle system to remain synchronized with the variable-speed video content, resolving the timing accuracy issue while maintaining playback flexibility.
3Quantity of substance
If multiple subtitle packets are displayed simultaneously during variable speed reproduction, then more subtitle information can be shown, but priority management becomes complex and overlap control is difficult
Solution Approach 1:
The patent applies local quality by assigning different priority levels to different subtitle packets. Each subtitle is tagged with a priority value that indicates its importance or display urgency. When multiple subtitles overlap during variable speed reproduction, the reproducing device uses these priority values to determine which subtitles to display and which to suppress, creating a simple yet effective priority management system that handles multiple simultaneous subtitles without complex processing.
Data Source
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AI summary
Subtitle display during variable speed reproduction processing is made to be able to be satisfactorily performed. A video stream is generated configured by a video packet having encoded image data in a payload. A subtitle stream is generated configured by a subtitle packet that has subtitle information in a payload and in which subtitle display priority information according to the subtitle information is inserted. A multiplexed stream including the video stream and the subtitle stream is generated and transmitted. In a case where an overlap period occurs in display periods of a plurality of subtitles in a variable speed reproduction mode (in a case of N times speed (N > 1)), selection of which subtitle to be displayed is facilitated by referring to the priority information, and satisfactory subtitle display reflecting an intention of the production side becomes possible.