IP Packet Reference Clock Extraction for Broadcast Precision
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Solution Overview
Problem
Conventional MMT schemes face challenges in acquiring high-precision reference clock information due to the complexity and time required in extracting it from multiple packet layers, leading to potential jitter and precision issues in broadcasting systems.
Innovation Solution
The proposed method involves generating frames using IP packets with the reference clock information stored in a distinct data structure, omitting header compression, and storing control information separately, allowing for quicker and more precise acquisition of reference clock information by specifying its position within the frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If reference clock information is embedded within MMT packet structures across multiple layers, then comprehensive clock information can be transmitted, but extraction complexity and acquisition time increase significantly
Solution Approach 1:
The patent extracts reference clock information from the complex MMT packet structure and places it in a dedicated, easily accessible location within the IP packet header. This separation allows the reception apparatus to acquire clock information without navigating through multiple MMT packet layers, significantly reducing extraction complexity while maintaining information completeness.
Solution Approach 2:
The patent segments the transmission structure by creating distinct layers: IP packet level (with reference clock information in header), MMT packet level (for content data), and application level. This segmentation allows the reception apparatus to acquire clock information independently from content data, reducing overall system complexity.
2Loss of energy
If header compression processing is applied to IP packets containing reference clock information, then bandwidth efficiency improves, but acquisition precision and speed deteriorate
Solution Approach 1:
The patent applies different processing qualities to different parts of the IP packet: the header containing reference clock information is transmitted without compression to ensure high precision and fast acquisition, while the payload containing MMT packets can utilize compression for bandwidth efficiency. This local quality differentiation resolves the contradiction between compression efficiency and precision.
3Loss of time
If reference clock information is stored in control information separate from frames, then acquisition speed improves, but integration with content transfer becomes complex
Solution Approach 1:
The patent merges the reference clock information transmission with the existing IP packet infrastructure by placing it in the IP packet header that already accompanies MMT packets for content transfer. This integration approach allows fast acquisition without requiring separate transmission channels, resolving the contradiction between speed and integration complexity.
Data Source
AI summary
A transmission method includes generating one or more frames for content transfer using IP packets, and transmitting the one or more generated frames by broadcast. Each of the one or more frames contains a plurality of second transfer units, each of the plurality of second transfer units contains one or more first transfer units, each of the one or more first transfer units contains at least one of the IP packets, an object IP packet of the IP packets contains first reference clock information indicating time for reproduction of the content in data structure different from MMT packet data structure, the object IP packet being stored in a first transfer unit positioned at a head in the one or more frames, the one or more frames contains control information storing second reference clock information indicating time for reproduction of the content, and header compression processing on the object IP packet is omitted.