MMTP Packet Leap Second Correction via Timestamp Adjustment
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Solution Overview
Problem
Current broadcasting systems using MPEG-2 TS and RTP schemes face challenges in maintaining correct packet order and clock synchronization during leap second occurrences due to the absence of leap second indicators in MMTP packets, leading to incorrect video or audio reproduction and reduced audio quality.
Innovation Solution
A transmitting system and multiplexing apparatus that extract and adjust timestamp information to account for leap second corrections, ensuring correct packet order and synchronization by using a controller to determine discontinuity times and adjust transmission timing based on leap second processing information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MMT standards are adopted for media transport, then network adaptability and versatility are improved, but the ability to handle leap second corrections is lost due to absence of leap second indicators in MMTP packets
Solution Approach 1:
The patent introduces an intermediary mechanism by embedding leap second indicator information within the MMTP packet structure itself, specifically in the management information field. This allows the MMTP protocol to carry leap second correction data without requiring external NTP packet infrastructure, thus maintaining network adaptability while restoring leap second correction capability.
Solution Approach 2:
The patent merges the leap second indicator functionality with the existing MMTP packet management information field. By combining these previously separate functions into a unified packet structure, the system achieves both network adaptability of MMT and leap second correction capability without requiring separate protocols or external indicators.
2Speed
If NTP short format timestamp is used in MMTP header, then packet transmission speed is improved, but clock synchronization accuracy deteriorates during leap second events
Solution Approach 1:
The patent applies preliminary action by embedding the leap second indicator information in advance within the MMTP packet structure before transmission. This allows receiving devices to anticipate and prepare for upcoming leap second corrections, maintaining both fast transmission using NTP short format timestamps and accurate clock synchronization by having the correction information readily available.
3Reliability
If leap second indicator is added to MMTP packet, then leap second correction capability is improved, but packet structure complexity increases
Solution Approach 1:
The patent makes the management information field in the MMTP packet multi-functional by using it to carry both常规 management data and leap second indicator information. This universal approach allows the packet structure to maintain its original simplicity while gaining leap second correction capability, as the same field serves multiple purposes rather than requiring additional dedicated fields.
Data Source
AI summary
A transmitting system includes an outputting apparatus and a multiplexing apparatus. The outputting apparatus transmits MMTP packets to which an NTP short format timestamp is added. The multiplexing apparatus multiplexes the MMTP packets. The multiplexing apparatus includes an extractor, a controller, a determiner, a management information generator, a continuity determiner, and a transmission timing adjuster. The transmission timing adjuster writes, for adjustment of a transmission timing of an MMTP packet being close to an MMTP packet in which an NTP short format timestamp value is discontinuous, time information taking a leap second processing into consideration, to the NTP short format timestamp of the MMTP packet.