IP Broadcast Clock Synchronization via Segmented Timing Metadata
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Solution Overview
Problem
Current IP-based broadcast schemes, such as MMT using the MP4 ISO Base Media File Format, face challenges in achieving low delay and are susceptible to packet loss due to the need to transport metadata in GOP units, which increases delay and affects synchronization.
Innovation Solution
A transmission apparatus and method that includes a clock generation unit for synchronizing with external time information, a time information generation unit for generating time information including frequency, and a transmission unit that embeds time acquisition information for decoding and presentation times into the broadcast signal, allowing for efficient clock and presentation synchronization by reducing delay and packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If metadata are transported collectively in GOP unit, then transportation efficiency is improved, but delay amount is increased and low delay requirement is not satisfied
Solution Approach 1:
The patent segments the metadata transport from the GOP unit by introducing separate timing information packets that carry presentation time and decoding time independently. This allows metadata to be transported efficiently while avoiding the delay penalty of GOP-level collective transport, as the timing information is extracted and processed separately at the presentation unit level.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and embedding timing information (presentation time and decoding time) directly into the media packets before transmission. This preliminary timing annotation allows the reception side to immediately process and synchronize media without waiting for subsequent metadata, thereby reducing delay while maintaining transportation efficiency.
2Device complexity
If metadata are determined by GOP amount, then collective transport is simplified, but influence by packet loss is increased
Solution Approach 1:
The patent segments metadata into individual timing information packets associated with each presentation unit rather than batching them by GOP. This segmentation ensures that packet loss in one unit does not affect the entire GOP, improving reliability while maintaining simplified transport through standardized single-unit timing packets.
Solution Approach 2:
The patent implements feedback mechanisms at the packet level by including timing information that enables the reception side to track and compensate for packet loss independently for each presentation unit. This granular feedback allows for more reliable reconstruction of the media stream compared to GOP-level metadata determination.
3Manufacturing precision
If clock synchronization is implemented in IP broadcast scheme, then presentation synchronization is achieved, but system complexity is increased
Solution Approach 1:
The patent applies self-service by having the transmission side automatically generate and embed timing information (presentation time and decoding time) directly into the media packets as they are transmitted. This eliminates the need for complex external synchronization systems, as the timing data is self-contained within the packets themselves, achieving precise presentation synchronization without increasing system complexity.
Data Source
AI summary
In a broadcast scheme of transportation in an IP scheme, clock synchronization and presentation synchronization are well implemented. A clock synchronizing with time information acquired from an outside is generated. Time information including frequency information of the clock and synchronizing with the time information acquired from the outside is generated. A broadcast signal including transmission media, time acquisition information for acquiring decoding time and presentation time for every presentation unit of the transmission media obtained based on the generated time information, and the generated time information is transmitted.