SCTE-35 Message Tunneling via Closed Captioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-level transmission architectures, SCTE-35 messages and other critical data within digital television broadcasts are often stripped out by intermediate transmitters, leading to their loss and inability to reach downstream components such as set-top boxes and uplink centers.
Innovation Solution
Embedding SCTE-35 messages within a closed captioning service of the transport stream, using a digital television closed caption (DTVCC) inserter to detect and generate corresponding messages, which can survive decoding and re-encoding processes, and extracting them using a DTVCC extractor at downstream systems to re-multiplex them back into the transport stream or perform ad insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If SCTE-35 messages are transmitted in a separate packet identifier in the transport stream, then message delivery is straightforward at the source, but intermediate transmitters strip out these messages causing loss of information downstream
Solution Approach 1:
The patent embeds SCTE-35 messages within the closed captioning data structure, nesting the message data inside the closed captioning packet framework. This allows messages to be carried within an existing data structure that intermediate transmitters preserve, preventing message loss without requiring complex new transmission infrastructure
Solution Approach 2:
The closed captioning service acts as an intermediary carrier that intermediate transmitters are already configured to preserve. By using this existing intermediary data structure to transport SCTE-35 messages, the system leverages the intermediary's preservation behavior to protect messages from being stripped out
2Loss of information
If closed captioning service 63 is used for tunneling messages, then message preservation through intermediates is achieved, but the service cannot be used for actual closed captioning delivery
Solution Approach 1:
The patent divides the closed captioning service resources into multiple segments or channels. Certain closed captioning services (like service 63) are designated for message tunneling while others remain available for actual closed captioning delivery. This segmentation allows both message preservation and closed captioning functionality to coexist without conflict
Solution Approach 2:
The closed captioning infrastructure is designed to support multiple functions: some services deliver actual closed captioning content while others tunnel SCTE-35 messages. This multi-functionality allows the same infrastructure to serve both message transmission and closed captioning delivery purposes through different service channels
3Measurement precision
If absolute presentation timestamp is used in SCTE-35 messages, then timing accuracy is maintained, but timing drift occurs after multiple transcodings at intermediate systems
Solution Approach 1:
The patent transforms the timestamp parameter from an absolute reference to a relative reference. Instead of using absolute presentation timestamps that drift after multiple transcodings, the system uses relative timestamps measured from a common reference frame. This parameter change makes timing accurate across multiple intermediate processing stages without accumulation of drift
4Reliability
If SCTE-35 messages are embedded within closed captioning service, then messages survive decoding and re-encoding processes, but extraction and processing at downstream systems becomes more complex
Solution Approach 1:
The closed captioning data structure serves as an intermediary container that protects SCTE-35 messages during transmission through intermediate transcoders. Downstream systems use DTVCC extractors to retrieve messages from this intermediary structure, allowing messages to survive transcoding while providing a defined extraction mechanism at the destination
Data Source
AI summary
Original transmitters of television broadcast content, such as national broadcasters, may tunnel various data such as SCTE-35 messages through a special closed captioning service before handoff to their local affiliates. The tunneled SCTE-35 messages may thus survive the re-encoding of both the local broadcaster to an over-the-air (OTA) retransmission, and re-encoding by any subsequent cable or satellite television providers as well. An uplink center and television service provider (e.g., a cable or satellite system) may receive the transport stream from the local broadcaster, may strip out the tunneled SCTE-35 messages from extra closed captioning streams at the uplink, re-create the SCTE-35, and then process it at the uplink of the satellite system, for example, by performing ad insertion, re-muxing the SCTE-35 for the satellite broadcast, and/or modifying it and sending it over the satellite broadcast on a separate PID to the set top boxes for those STBs for ad insertion.