Digital Video Apparatus Channel Change Time Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital video apparatuses experience significant channel change delays due to the GOP structure and processing components like buffering, forward error correction, and error concealment, which hinder rapid channel switching in digital television broadcast systems.
Innovation Solution
A method involving the reception and processing of two video streams, where one stream (channel change stream) is delayed and has characteristics such as shorter GOP size, lower resolution, or lower bit rate, allowing for immediate rendering upon channel change, while the other stream (regular stream) undergoes necessary quality enhancements without additional delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If video streams are processed with quality enhancements (buffering, FEC, error concealment), then video quality and reliability are improved, but channel change time increases
Solution Approach 1:
The system pre-buffers the channel change stream in advance before a channel change is requested. This preliminary buffering action ensures that when a channel change occurs, the buffered stream is immediately available for playback without requiring real-time processing delays for quality enhancements, thus reducing channel change time while maintaining video quality through the pre-applied FEC and error concealment.
2Reliability
If buffering is applied for traffic shaping and FEC protection, then error recovery capability is improved, but processing delay increases
Solution Approach 1:
The buffering for traffic shaping and FEC protection is performed in advance during the pre-buffering phase, before the channel change is actually requested. This preliminary action allows the system to have error recovery capabilities ready without adding real-time processing delay during the channel change event itself.
3Reliability
If error concealment with advanced algorithms (optical flow based processes) is used, then concealment quality is improved, but computational complexity and processing time increase
Solution Approach 1:
Error concealment processing is performed in advance on the pre-buffered channel change stream, allowing advanced algorithms to be applied without impacting real-time channel change performance. The computational complexity is absorbed during the preliminary buffering phase rather than during the actual channel change event.
4Measurement precision
If the apparatus waits for the first I frame before decoding and displaying pictures, then decoding accuracy is improved, but channel change delay increases significantly
Solution Approach 1:
The system creates a separate channel change stream that is a copy or alternative version of the main video stream, specifically optimized for fast channel changes. This copy stream is pre-buffered and can be immediately decoded and displayed without waiting for I frames, while the original stream maintains its standard GOP structure for normal playback.
Solution Approach 2:
The channel change stream is prepared and buffered in advance with appropriate frame structures that allow immediate decoding. This preliminary preparation eliminates the need to wait for I frames during actual channel changes, as the pre-buffered stream is ready for immediate playback.
Data Source
AI summary
A digital video apparatus provides reduced channel change times. According to an exemplary embodiment, the digital video apparatus includes at least one receiver for receiving first and second video streams representing the same program, wherein the first video stream has at least one characteristic different from the second video stream; a first signal processor for processing the first video stream to generate a first processed video stream; a second signal processor for processing the second video stream to generate a second processed video stream having a delay with respect to the first processed video stream; a renderer for rendering the second processed video stream responsive to a channel change command; and a switch for switching from the second processed video stream to the first processed video stream after the renderer begins rendering the second processed video stream, and thereby causing the renderer to begin rendering the first processed video stream.