Hierarchical Video Transmission GOP Boundary Detection
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Solution Overview
Problem
Existing methods for transmitting hierarchically encoded video streams in MPEG-2 TS face challenges in detecting GOP boundaries and associating GOPs between layers, particularly when layers are multiplexed with different PIDs, leading to uncertainties in temporal relationships and potential decoding errors.
Innovation Solution
A video transmission device and method that extract access units from a hierarchically encoded bit stream, impart decoding timestamps, and detect GOP head access units to assign a common GOP number to both base and enhancement layers, ensuring correct hierarchical transmission and decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If layers are multiplexed with different PIDs to enable easier layer processing, then ease of operation is improved, but reliability deteriorates due to uncertainties in temporal relationships between layers
Solution Approach 1:
The patent introduces an intermediary mechanism (timestamp correlation and sequence number mapping) that mediates between layers multiplexed with different PIDs. This intermediary tracks and correlates the temporal relationships between base layer and enhancement layer packets, ensuring accurate synchronization despite the layers being separated by different PIDs for easier processing.
2Device complexity
If GOP boundaries are not correctly detected and associated between layers, then device complexity is reduced, but manufacturing precision deteriorates due to incorrect hierarchical transmission
Solution Approach 1:
The patent applies preliminary action by pre-establishing the correlation between GOP boundaries in base layer and enhancement layer before transmission. Sequence numbers and timestamps are assigned and correlated in advance at the encoder, allowing the receiver to correctly associate GOPs across layers without requiring complex real-time boundary detection, thus maintaining transmission accuracy while reducing receiver complexity.
3Productivity
If variable-length packets are used in MMT for efficient IP transmission, then productivity is improved, but reliability deteriorates due to difficulties in detecting GOP boundaries and associating layers
Solution Approach 1:
The patent changes the parameters used for boundary detection from fixed packet structures (as in MPEG-2 TS) to timestamp and sequence number parameters that work effectively with variable-length MMT packets. By using decoding timestamps and GOP sequence numbers as the basis for boundary detection and layer association, the system maintains high reliability in GOP boundary detection while benefiting from the transmission efficiency of variable-length packets.
Data Source
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AI summary
The present disclosure aims to provide a method for detecting a GOP boundary of an encoded bit stream of each layer and associating GOPs of the layers for hierarchical transmission in a video transmission device that transmits a hierarchically encoded bit stream. The present disclosure provides a video transmission device and a video transmission method that detect a GOP head access unit in a base layer of a hierarchically encoded bit stream by analyzing the base layer and detect a head access unit of an enhancement layer of an identical GOP to that of the aforementioned access unit from a decoding time stamp of the access unit by using the relationship between a decoding time stamp of the base layer and a decoding time stamp of the enhancement layer.