MPEG Stream Splicing via Low-Information Frame Removal
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Solution Overview
Problem
Splicing MPEG compressed video and audio streams is challenging due to differences in encode rates, DTS-PCR values, and frame boundaries, leading to decoder buffer overflows and unsynchronized playback, requiring expensive hardware and software solutions for transcoding or requantizing.
Innovation Solution
A software-based method that pre-identifies low-information frames for removal and insertion of advertisements, adjusting DTS-PCR values and frame timing to maintain decoder buffer stability, allowing seamless splicing without pre-conditioning the streams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transcoding or requantizing methods are used to splice MPEG streams, then splicing reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and removes low-information frames (such as black frames or frames with minimal visual content) from the MPEG stream to create space for advertisement insertion. This extraction approach avoids the need for complex transcoding operations while maintaining stream integrity and decoder buffer stability, thereby resolving the contradiction between splicing reliability and device complexity
Solution Approach 2:
The patent changes temporal parameters (DTS-PCR values and frame timing) rather than spatial or quality parameters. By adjusting timing parameters and removing low-information frames, the system achieves seamless splicing without requiring expensive transcoding hardware, thus improving reliability while reducing device complexity
2Adaptability or versatility
If advertisement streams with different encode rates are spliced into program streams, then ad insertion flexibility is improved, but decoder buffer stability deteriorates
Solution Approach 1:
The patent performs preliminary removal of low-information frames before advertisement insertion to pre-adjust the decoder buffer levels. This preliminary action ensures that when advertisements with different encode rates are inserted, the decoder buffer remains stable and avoids overflow or underflow conditions, thus maintaining both flexibility and stability
Solution Approach 2:
The patent uses low-information frames as intermediary elements between the program stream and advertisement stream. These frames act as buffer-adjustment mediators that allow seamless transitions between streams with different encode rates while maintaining decoder buffer stability, enabling flexible ad insertion without compromising buffer integrity
3Productivity
If frame boundaries are not dynamically synchronized during splicing, then splicing speed is improved, but video and audio synchronization deteriorates
Solution Approach 1:
The patent replaces complex mechanical synchronization mechanisms (dynamic frame boundary alignment) with a simpler temporal parameter adjustment system. By modifying DTS-PCR values and removing low-information frames, the system achieves synchronization without requiring frame-by-frame mechanical alignment, thus improving splicing speed while maintaining synchronization precision through software-based temporal control
Data Source
AI summary
Techniques are provided to perform seamless or non-seamless ad insertion using a low-complexity process. Delay is introduced into a transport stream to prevent decoder buffer overflow. Delay buildup in the transport stream is reduced by removing pre-identified redundant or near redundant frames. Pre-identification of frames for removal reduces the processing required at the splice points, while maintaining a minimum overall delay in the transport stream.