Fast Channel Change Server Audio Video Packet Timing Adjustment
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Solution Overview
Problem
IPTV systems face significant channel change delays due to the uncontrolled interval between audio and video packets, leading to increased synchronization time and negatively impacting user experience.
Innovation Solution
The FCC method involves an FCC server adjusting the time interval between audio and video packets in a multicast channel stream, sending adjusted packets in unicast mode to user equipment, ensuring quick synchronization and reducing channel change time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the interval between audio packet and video packet in multicast stream is not controlled, then the network can transmit packets normally, but the audio and video synchronization time increases and channel change speed decreases
Solution Approach 1:
The FCC server performs preliminary action by adjusting the time interval between audio packets and video packets in advance. Specifically, the server determines a video packet containing a start I-frame and backward searches for the corresponding audio packet based on PTS, then replaces the first audio packet after the video packet with the searched audio packet. This preliminary adjustment of packet timing enables quick synchronization after channel change without waiting for natural packet arrival intervals.
Solution Approach 2:
The invention changes the time interval parameter between audio and video packets from its natural uncontrolled state to a controlled adjusted state. The FCC server modifies this parameter by calculating and implementing a specific time interval based on PTS values, transforming the packet transmission from passive to active control, thereby reducing synchronization time and improving channel change speed.
2Loss of time
If the FCC server adjusts the time interval between audio and video packets, then the audio and video synchronization time is reduced, but the packet processing complexity increases
Solution Approach 1:
The FCC server acts as an intermediary between the multicast stream source and the user equipment. It receives the original multicast packets, performs the complex task of adjusting audio-video packet intervals, and sends the adjusted packets to users. This intermediary approach centralizes the processing complexity at the server level rather than requiring each user device to handle complex packet timing adjustments, thereby managing system complexity effectively.
Solution Approach 2:
The FCC server creates a copy of the multicast stream and performs packet adjustment on this copy before delivering it to users. By working with a copied version of the stream rather than modifying the original multicast transmission directly, the server can implement complex timing adjustments without affecting other users or the original broadcast, thus managing processing complexity while maintaining service quality.
3Loss of time
If the terminal receives all channel signals at the same time in conventional cable television, then the channel change time is short (approximately 0.5 second), but the IPTV system cannot achieve the same speed due to bandwidth limitations and complex network signaling
Solution Approach 1:
The invention segments the audio and video packet transmission process into controllable individual units. Instead of treating channel signals as a monolithic stream, the FCC server adjusts and controls each audio packet and video packet individually, allowing precise timing control. This segmentation enables the system to overcome bandwidth limitations and signaling complexity by managing packets as discrete, controllable units rather than a complex integrated stream.
Data Source
AI summary
Embodiments of the present invention provide a fast channel change method and a fast channel change server. After receiving a fast channel change request of user equipment, the fast channel change server adjusts a time interval between a video packet and a corresponding audio packet in a channel multicast packet, and sends an adjusted channel multicast packet to the user equipment. In this way, an audio and video synchronization time after the user equipment receives a channel data packet is reduced.