XML Subtitles in MPEG-2 Transport Stream for UHD Broadcast
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Solution Overview
Problem
Digital broadcast systems face challenges in data transmission efficiency, robustness, and network flexibility, particularly when handling large data volumes and mobile reception, and conventional subtitle data methods like bitmaps lead to decreased bandwidth efficiency and deteriorated sharpness in UHD services.
Innovation Solution
The implementation of XML-based subtitles, such as EBU-TT-D, IMSC1, and WebVTT, which are multiplexed into MPEG-2 TSs and transmitted through a broadcast system, enabling efficient signaling and transmission/reception operations, supporting future hybrid broadcast services using terrestrial networks and the Internet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bitmap subtitle data is used, then subtitle information can be provided, but bandwidth efficiency decreases and sharpness deteriorates in UHD services
Solution Approach 1:
The patent replaces the conventional bitmap image-based subtitle system with an XML-based text markup system. Instead of transmitting rasterized pixel data, the invention uses structured text tags (e.g., <subtitle>, <position>, <color>) to describe subtitle content, positioning, and styling. This substitution transforms the subtitle representation from a mechanical pixel-grid system to a semantic text-based system, enabling lossless scaling to any resolution without bandwidth waste.
Solution Approach 2:
The invention changes the fundamental parameters of subtitle data representation from fixed-resolution bitmap dimensions (width, height, pixel values) to scalable text-based parameters (font size, position coordinates, color codes, timing). This parameter transformation allows subtitles to be rendered at any UHD resolution without retransmission, as the receiver can generate high-resolution subtitle graphics from the compact XML description.
2Quantity of substance
If digital broadcast systems transmit large amounts of video/audio data, then HD images and multichannel audio can be provided, but data transmission efficiency and network robustness need improvement
Solution Approach 1:
The patent segments the broadcast data stream into distinct MPEG-2 Transport Stream (TS) packets, each carrying specific service components (video, audio, XML subtitles, metadata). This segmentation allows independent encoding, error protection, and transmission optimization for each data type, improving overall transmission efficiency and enabling selective reception based on device capabilities.
Solution Approach 2:
The invention creates a universal XML-based subtitle framework that can serve multiple functions: providing closed captioning for hearing-impaired viewers, offering multi-language support through language-specific XML files, enabling stylized subtitle presentations, and facilitating subtitle synchronization. This multi-functional approach replaces multiple specialized subtitle systems with a single versatile XML-based solution.
3Loss of energy
If XML-based subtitles are multiplexed into MPEG-2 TSs, then bandwidth efficiency improves and sharpness is maintained, but signaling and transmission/reception operations become more complex
Solution Approach 1:
The patent introduces standardized signaling structures (service layer signaling, transport layer signaling) that act as intermediaries between the XML subtitle content and the MPEG-2 TS transmission system. These signaling mechanisms provide a structured interface for describing subtitle service parameters, mapping XML data to transport packets, and coordinating transmission/reception operations, thereby managing complexity through standardization.
Data Source
AI summary
The present invention presents a method for transmitting a broadcast signal. The method for transmitting a broadcast signal, according to the present invention, presents a system capable of supporting a next-generation broadcast service in an environment supporting next-generation hybrid broadcasting using a terrestrial broadcast network and an Internet network. In addition, presented is an efficient signaling method capable of covering both the terrestrial broadcast network and the Internet network in the environment supporting the next-generation hybrid broadcasting.