Reference Clock Extraction in MMT Broadcast Transmission
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Solution Overview
Problem
Conventional MMT schemes face challenges in acquiring high-precision reference clock information due to complex processes and potential jitter in software-based extraction, especially when reference clock information is stored in MMT packets and requires extraction through multiple layers, leading to longer acquisition times and lower precision.
Innovation Solution
The method involves generating transfer frames that store IP packets with reference clock information at the head of streams, allowing for simplified acquisition by positioning the reference clock information in TLV packets or control information, reducing the need for extensive software processing and enabling hardware-based extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference clock information is stored in MMT packets and extracted through multiple layers, then the information can be obtained, but the acquisition process becomes complex and time-consuming
Solution Approach 1:
The patent extracts reference clock information from deep within the MMT packet structure and places it in the IP packet header or TLV packet header, making it immediately accessible without requiring multi-layer extraction processes
Solution Approach 2:
The reference clock information is preliminarily positioned in the IP packet header or TLV packet header before the data reaches the reception apparatus, enabling immediate access without requiring complex extraction processes through multiple protocol layers
2Measurement precision
If reference clock information is extracted through software-based processes, then the information can be acquired, but software jitter affects the precision
Solution Approach 1:
The patent replaces software-based extraction with hardware-based extraction by positioning the reference clock information in the IP packet header or TLV packet header, which can be directly accessed by hardware circuits without involving software processing, thereby eliminating software jitter
3Loss of information
If reference clock information is stored in MMT packets, then the information is available, but extensive software processing is required
Solution Approach 1:
The patent extracts the reference clock information from the MMT packet structure and places it in the IP packet header or TLV packet header, eliminating the need for extensive software processing through multiple protocol layers
Solution Approach 2:
The reference clock information is preliminarily positioned in easily accessible header structures (IP packet header or TLV packet header) before transmission, so that the reception apparatus can obtain it with minimal processing
Data Source
AI summary
A transmission method includes: generating one or more transfer frames that each store one or more streams used for content transfer; and transmitting the one or more generated frames through broadcast, each of the one or more streams storing one or more second transfer units, each of the one or more second transfer units storing one or more first transfer units, and each of the one or more first transfer units storing one or more Internet Protocol (IP) packets. In at least one stream among the one or more streams, each of the first transfer units positioned at a head contains reference clock information indicating time used for reproduction of the content.