Mid-GOP Fast Channel-Change Video Decoding
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Solution Overview
Problem
Current channel change technologies are limited by the need for short group of pictures (GOP) sizes to minimize channel change time, which compromises video compression efficiency and increases bandwidth requirements, as decoding typically starts from the next random access point in the new channel.
Innovation Solution
A content delivery system that allows decoding to begin from the middle of a GOP, using a server to provide the minimum required reference frames needed for decoding, reducing the need for short GOPs and minimizing bandwidth usage while maintaining fast channel change times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If short GOP sizes are used to minimize channel change time, then channel change speed is improved, but video compression efficiency deteriorates and bandwidth requirements increase
Solution Approach 1:
The patent segments the video stream by identifying and extracting only the necessary reference frames (I-frames or key P-frames) from the middle of a GOP, rather than transmitting the entire GOP or waiting for the next random access point. This allows the receiver to decode and display video content immediately with minimal data, resolving the contradiction between fast channel change and efficient compression.
Solution Approach 2:
The system extracts and transmits only the essential reference frames needed for decoding from the middle of a GOP structure. By taking out just these critical frames rather than the entire GOP sequence, the patent enables fast channel switching while maintaining compression efficiency and reducing bandwidth consumption.
2Ease of operation
If decoding starts from the next random access point, then channel change can be achieved, but channel change time increases due to waiting for the next I-frame
Solution Approach 1:
The patent applies preliminary action by pre-identifying and preparing reference frames at strategic positions within the GOP structure. The server proactively provides these reference frames to the receiver before a channel change is requested, enabling immediate decoding and display without waiting for the next random access point in the stream.
Solution Approach 2:
The patent introduces an intermediary mechanism where the server acts as a mediator between the video stream and the receiver. The server intercepts the stream, extracts necessary reference frames, and delivers them directly to the receiver, bypassing the limitation of waiting for natural random access points and thereby reducing channel change time.
3Loss of energy
If large GOP sizes are used for better compression, then bandwidth requirements decrease, but channel change time increases
Solution Approach 1:
The patent segments the large GOP structure into manageable components by identifying and extracting only the essential reference frames needed for decoding. This allows the system to maintain large GOP sizes for compression efficiency while enabling fast channel changes by transmitting only the segmented critical portions.
Solution Approach 2:
The patent applies local quality by providing different amounts of data depending on the specific decoding needs. For channel changes, only the necessary reference frames are transmitted with high priority, while the rest of the GOP structure maintains its compressed format. This localized optimization resolves the contradiction between compression efficiency and channel change speed.
Data Source
AI summary
A system comprising a decoder to receive an encoded video stream including video frames including reference and non-reference frames, and decode the reference frames, a processor to receive a request from an end-user rendering device requiring a first reference frame as part of decoding the encoded video stream of the first channel from the middle of a group of pictures of the encoded video stream, wherein a second reference frame is a reference frame for the first reference frame in the received encoded video stream, an encoder to encode the decoded first reference frame yielding a re-encoded first reference frame so that decoding the re-encoded first reference frame is not dependent upon the second reference frame, and a transmitter to transmit the re-encoded first reference frame to the end-user rendering device. Related apparatus and methods are also described.