Set-Top Box Channel Change Delay Reduction via Pre-Fetched PMT
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Solution Overview
Problem
Digital broadcasting systems experience channel change delays due to the time required for set-top boxes to interpret program association tables and obtain program map table information when a user requests a channel change via an IP network.
Innovation Solution
The system employs a digital broadcast server that transmits a multiplexed stream containing down and up broadcast data, along with difference data, allowing the set-top box to quickly access and decode the selected channel by using pre-defined PID values, thereby reducing channel change delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the set-top box uses traditional channel changing method by interpreting PAT to obtain PMT information, then the channel change function is achieved, but the channel change delay increases
Solution Approach 1:
The patent applies preliminary action by pre-obtaining PMT information and storing it in a buffer before the actual channel change occurs. When a channel change is requested, the pre-fetched PMT information is immediately available, eliminating the delay caused by real-time PAT interpretation. This advance preparation of data resolves the contradiction by reducing channel change delay without adding significant complexity to the device.
2Speed
If the set-top box accesses the requested channel and interprets PAT in real-time to obtain PMT information, then the channel change function is achieved, but the channel change speed decreases
Solution Approach 1:
The patent implements preliminary action by fetching and buffering PMT information in advance before channel changes are requested. This pre-processing approach allows the set-top box to immediately use stored PMT data when a channel change occurs, significantly increasing channel change speed without requiring complex real-time processing during the actual channel switch.
3Loss of time
If the set-top box decodes packets received from the IP network in real-time, then the broadcast data is provided to the digital television, but the channel change delay increases
Solution Approach 1:
The patent applies preliminary action by pre-decoding and buffering broadcast data before channel changes are requested. When a user changes channels, the pre-decoded data is already available in the buffer, eliminating the time required for real-time decoding during channel transitions. This approach reduces channel change delay while maintaining efficient data processing through advance preparation.
Data Source
AI summary
An apparatus and method for changing a channel in a digital broadcasting system are provided. The apparatus includes: a digital broadcast server for transmitting a multiplexed stream obtained by multiplexing at least one down broadcast data, and transmitting up broadcast data and at least one difference broadcast data; and a set-top box for accessing a channel over which the multiplexed stream is transmitted to perceive a down broadcasting PID (program identification) set for transmitting at least one down broadcast data contained in the multiplexed stream, upsizing and outputting down broadcast data having a down broadcasting PID corresponding to selected channel information from the multiplexed stream when a user selects a certain channel, summing difference broadcast data corresponding to a difference broadcasting PID and broadcast data obtained by upsizing the down broadcast data corresponding to the channel information, and outputting the result. As a result, a channel change delay which occurs when changing a channel is reduced.