Splice Signaling Buffer Characteristics in Transport Streams
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Solution Overview
Problem
In television systems, particularly those using AVC/H.264 video coding standard, finding and managing precise splice points for concatenating video segments is challenging due to difficulties in identifying the exact point in the video stream corresponding to a presentation time stamp (PTS) value, leading to errors such as buffer underrun/overrun and non-seamless transitions.
Innovation Solution
The implementation of assistive information systems that provide and process information to signal splice points using presentation time stamps, along with properties of compressed and decoded picture buffers, to manage buffer levels and ensure seamless transitions by signaling assistive information in transport packets, such as CPB properties and YTBOP intervals, allowing for explicit correspondence with existing mechanisms and preventing buffer underflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If assistive information is provided in transport packets to signal splice points and buffer properties, then buffer management precision and transition seamlessness are improved, but device complexity and processing overhead increase
Solution Approach 1:
The patent introduces an intermediary mechanism (assistive information field) within the existing transport packet structure to carry splice point and buffer property data. This intermediary layer enables precise buffer management without requiring fundamental changes to the core video coding architecture, thus improving precision while controlling complexity increase.
Solution Approach 2:
The assistive information structure is designed to serve multiple functions: signaling splice points, indicating buffer levels, and providing transition control data all within a unified framework. This multi-functionality reduces the need for separate signaling mechanisms, thereby limiting the increase in device complexity while achieving comprehensive buffer management.
2Reliability
If buffer levels are actively managed using CPB and DPB properties, then transition seamlessness is improved, but processing time and computational overhead increase
Solution Approach 1:
The patent applies preliminary action by signaling buffer properties (CPB buffer level, DPB buffer level) and splice point information in advance within transport packets before the actual splicing operation. This allows the receiving device to prepare buffer management actions beforehand, reducing real-time processing time while ensuring reliable buffer synchronization during transitions.
Solution Approach 2:
The assistive information provides feedback mechanisms that allow the receiving device to monitor buffer levels and adjust decoding operations accordingly. By continuously feedback buffer status through the transport stream, the system can prevent buffer underflow without requiring excessive computational overhead during critical transition periods.
3Measurement precision
If splice points are identified using PTS values in AVC/H.264 streams, then video concatenation accuracy is improved, but difficulty in locating exact splice points increases
Solution Approach 1:
The patent uses an intermediary signaling mechanism (assistive information field) that translates the abstract PTS value into concrete buffer level indicators and splice point markers. This intermediary layer bridges the gap between the theoretical PTS timing and the actual buffer state, making splice point detection more accurate and easier to implement in AVC/H.264 streams.
Solution Approach 2:
The patent replaces complex mechanical search methods for locating splice points (such as exhaustive scanning or heuristic analysis) with a more elegant information-theoretic approach using structured assistive information fields. This substitution reduces detection difficulty while maintaining or improving location accuracy by leveraging metadata rather than brute-force analysis.
Data Source
AI summary
In one method embodiments, providing a transport stream to a client device, the transport stream comprising a head stream and a tail stream, the head stream and the tail stream each comprising a compressed video sequence; providing information in a transport stream packet associated with the head stream, the information configured to cause the client device to selectively control an output of at least one of a plurality of pictures of the head stream yet to be output from a decoded picture buffer (DPB) at an out-point from the head stream to the trail stream.