Adaptive PAT PMT Table Transmission for xDSL Zapping
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Solution Overview
Problem
The existing broadcasting technologies face challenges in reducing resynchronization time after a program change while adhering to bandwidth constraints, particularly in low-speed channels like xDSL, where the limited bandwidth and lack of multiplexing lead to inefficiencies in transmitting redundant information.
Innovation Solution
The method involves calculating the optimum timing for sending the PAT table based on the anticipated position of the next random access point, allowing for synchronized transmission of subsequent tables within a 'zapping window', thereby optimizing zapping time and reducing bandwidth requirements by minimizing redundant data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If tables (PAT, PMT, ECM) are transmitted at regular intervals to ensure decoder resynchronization, then random access performance is improved, but bandwidth consumption increases due to redundant transmissions
Solution Approach 1:
The patent applies dynamics by making the table transmission interval adaptive rather than fixed. The system dynamically adjusts the transmission timing of PAT, PMT, and ECM tables based on the position of random access points in the video stream. Tables are transmitted at variable intervals synchronized with I-frame occurrences, allowing the system to optimize between resynchronization speed and bandwidth consumption according to actual stream conditions.
Solution Approach 2:
The patent changes the timing parameter of table transmissions from a fixed regular interval to a variable interval based on video stream characteristics. By calculating optimal transmission moments relative to random access point positions and considering decoder processing times, the system adjusts transmission parameters to minimize redundancy while ensuring timely resynchronization.
2Productivity
If tables are transmitted more frequently to reduce zapping time, then random access performance is improved, but bandwidth constraints are violated
Solution Approach 1:
The patent applies preliminary action by calculating and anticipating the optimal transmission moments for tables before actual transmission occurs. The system determines the position of upcoming random access points and schedules table transmissions to arrive at the decoder just in time for processing, avoiding both premature transmissions (which would be redundant) and delayed transmissions (which would slow zapping).
Solution Approach 2:
The system uses knowledge of its own transmission schedule and the video stream structure to self-optimize table transmission timing. By monitoring the stream for I-frame positions and calculating required processing times, the system autonomously determines when to transmit tables to achieve optimal zapping performance within bandwidth constraints.
3Loss of time
If the transmission interval of tables is reduced to minimize zapping time, then resynchronization performance is improved, but bandwidth efficiency deteriorates
Solution Approach 1:
The patent applies periodic action by synchronizing table transmissions with the periodic occurrence of random access points (I-frames) in the video stream. Rather than using a fixed time interval, the system creates a periodic transmission pattern tied to the video content structure, ensuring tables are transmitted at intervals that match the natural resynchronization opportunities in the stream.
Data Source
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AI summary
The method involves determining a maximum recognition and processing time of each of tables on reception side of multiplexed digital video stream. Cumulated duration e.g. duration of program association table (tmaxPAT), duration of program map table (tmaxPMT) and duration of entitlement control message (tmaxECM) of corresponding refractory period are calculated for the tables. Instant (tA) of next random access point is determined continuously during broadcasting. Packet encapsulating the tables at the latest is transmitted at an instant of the point anticipated from duration of the period.