Companion Stream GOP Redundancy Analysis for TV Channel Change
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Solution Overview
Problem
Current digital broadcasting systems, including IPTV and mobile systems, experience significant channel change delays due to the need for receiving and decoding I pictures, which increases the time to display a new selected program, and existing solutions to reduce this delay often require additional bandwidth.
Innovation Solution
A method that optimizes bandwidth by identifying and skipping redundant groups of pictures in the secondary video stream, using a GOP analyzer to determine if a group of pictures in the secondary stream is redundant with the main stream, and only transmitting non-redundant pictures to reduce channel change delay without affecting the receiver's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an additional secondary video program stream is transmitted to reduce channel change delay, then the channel change time is reduced, but the bandwidth consumption increases
Solution Approach 1:
The patent extracts only the essential non-redundant groups of pictures from the secondary stream for transmission, removing redundant data that would otherwise consume bandwidth. The encoder identifies and transmits only those GOPs in the secondary stream that are not already present in the main stream, achieving fast channel switching without proportional bandwidth increase.
Solution Approach 2:
The patent changes the parameter of GOP size and timing between main and secondary streams. By configuring the secondary stream with shorter GOP intervals and introducing a time delay, the system optimizes the balance between fast channel switching and bandwidth usage, transmitting only necessary picture groups at optimized intervals.
2Speed
If the GOP size in the secondary stream is reduced to enable faster decoding, then the channel switching speed is improved, but the data transmission volume increases
Solution Approach 1:
The patent extracts and transmits only the non-redundant GOPs from the secondary stream, removing duplicate picture groups that would increase data volume. The encoder compares GOP timestamps and spatial redundancy between main and secondary streams, transmitting only essential data needed for fast channel switching.
Solution Approach 2:
The patent applies partial action by transmitting only a subset of GOPs from the secondary stream rather than the complete stream. By selectively transmitting non-redundant GOPs based on timestamp comparison and redundancy analysis, the system achieves fast channel switching without the full bandwidth cost of a complete secondary stream.
3Loss of time
If a time delay is introduced between main and secondary streams to optimize decoding, then the channel change time is reduced, but the synchronization complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring a fixed time delay parameter between the main and secondary streams during encoding. This predetermined delay is set based on buffer characteristics and decoding requirements, eliminating the need for complex real-time synchronization adjustments and simplifying the overall system complexity.
Data Source
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AI summary
The present invention concerns a method for reducing the channel change time in a broadcast television system by encoding a termed companion service in addition to the main service. The companion service is sent along with the original service and helps the receiver to retrieve and display the new service more rapidly during the channel change process. With this solution the service is encoded and streamed in its original format, plus encoded and streamed in a low resolution format. The companion stream includes smaller GOPs than the main service. The method consists in selecting the GOPs transmitted in the companion stream that have a presentation time of an I picture close to the presentation time of an I picture of the original service. These selected GOPs of the companion stream will not be used and don't need to be transmitted. After a channel change action the receiver waits for the first compressed I picture to be decoded in both streams. As soon as two encoded I pictures are available to be decoded at the same time the receiver systematically chooses the main stream and never the companion stream