Frame Accurate Hot Failover for Redundant Bitstreams
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Solution Overview
Problem
Conventional live transcoding systems experience frame inaccurate failover transitions, leading to gaps or retransmission of video and audio frames, especially when inputs come from different networks with varying delays, causing output issues and buffer underflow or overflow.
Innovation Solution
A method for frame accurate hot failover that involves receiving and processing two redundant bitstreams, using delay buffers to align frames by timecodes, and adjusting buffer sizes based on reception times to ensure seamless switching without observable discontinuities or timing anomalies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If failover is implemented in conventional systems, then system reliability is improved, but frame accuracy deteriorates causing gaps or retransmission of video and audio frames
Solution Approach 1:
The patent pre-synchronizes the standby input to the active input before failover occurs, so that when switching happens, the standby is already aligned to the correct frame boundary. This preliminary synchronization action ensures that failover maintains frame accuracy without gaps or retransmissions.
Solution Approach 2:
The patent introduces an intermediary synchronization mechanism that mediates between the active and standby inputs. This intermediary aligns the timing and frame boundaries of both inputs, allowing seamless switching while maintaining frame accuracy.
2Reliability
If inputs from different networks are used to avoid network failure, then system reliability is improved, but frame synchronization deteriorates due to different network delays
Solution Approach 1:
The system performs preliminary synchronization of the standby input from a different network to the active input before failover. This advance alignment compensates for network delay differences, ensuring that when switching occurs, frame synchronization is maintained despite the standby coming from a network with different latency characteristics.
Solution Approach 2:
The patent dynamically adjusts timing parameters and buffer sizes for the standby input based on measured network delay characteristics. By changing these parameters to account for different network delays, the system maintains frame synchronization even when the standby input comes from a network with different latency.
3Productivity
If failover transition time is reduced for real-time output, then productivity is improved, but buffer underflow risk increases causing output gaps
Solution Approach 1:
The patent pre-loads and pre-synchronizes frames in the standby buffer before failover occurs. This preliminary preparation ensures that when switching happens rapidly, the output buffer immediately has synchronized frames available, preventing underflow and output gaps even during fast failover transitions.
Solution Approach 2:
The system maintains a cushion of pre-synchronized frames in the standby buffer before failover. This beforehand cushioning provides a safety margin that prevents buffer underflow during the transition, allowing rapid failover while maintaining output continuity.
Data Source
AI summary
A method for switching between two redundant bitstreams. The first bitstream may be presented to a first pipeline. The second bitstream may be presented to a second pipeline. The first bitstream and the second bitstream may contain redundant information received from independent sources. If the first bitstream fails, the method may present an output of the second pipeline to the output pipeline. Data in a buffer in the second pipeline may be used to pass a next frame to the output pipeline. A size of a buffer of the first pipeline and a size of the buffer in the second pipeline may be adjusted based on a time of reception of the first and the second bitstream.