Video Transcoding Caption Preservation Method
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Solution Overview
Problem
The transition from analog to digital television broadcasting has disrupted the preservation of closed captions, as digital formats do not inherently include the special video line used for analog caption data, necessitating a new method to carry and translate caption data across different formats while maintaining synchronization and accuracy.
Innovation Solution
A method and system for transcoding video streams that extract caption data, translate it into compatible formats, synchronize it with the transcoded video, and package it to ensure seamless integration, addressing issues like underflow, overflow, and errors, while adapting to different frame rates and formats such as CC, DTVCC, SAMI, and teletext.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If video transcoding is performed to adapt to different digital formats, then format compatibility is improved, but caption data may be lost or desynchronized
Solution Approach 1:
The system extracts caption data from the input video stream before transcoding begins. By performing this extraction action in advance, the caption data is separated from the video stream and preserved in a dedicated buffer, ensuring it remains intact throughout the transcoding process and can be accurately re-synchronized with the output stream.
Solution Approach 2:
The system introduces an intermediary buffer to store extracted caption data during the transcoding process. This buffer acts as a mediator between the input video stream and the output stream, allowing caption data to be temporarily held and then accurately re-synchronized with the transcoded video frames, preventing loss or desynchronization.
2Manufacturing precision
If caption data is extracted and translated to maintain accuracy, then caption precision is improved, but processing time increases
Solution Approach 1:
The system performs caption extraction and translation as preliminary actions before the main transcoding operation. By completing these time-consuming tasks in advance, the actual video transcoding can proceed more quickly, and the pre-processed caption data can be efficiently re-synchronized with the output video stream.
Solution Approach 2:
The system segments the video processing into distinct independent tasks: video transcoding and caption processing. By separating these operations, the caption data can be extracted, translated, and packaged independently in parallel with the video processing, reducing overall processing time while maintaining accuracy.
3Adaptability or versatility
If multiple caption formats are supported to accommodate different devices, then versatility is improved, but system complexity increases
Solution Approach 1:
The system implements a universal caption processing module that can handle multiple caption formats (CC, DTVCC, SAMI, teletext) through a single integrated translation and packaging mechanism. This multi-functional approach allows the system to support various formats without requiring separate processing paths for each format type.
Solution Approach 2:
The system manages format complexity by changing parameter settings rather than structural complexity. Different caption formats are handled by adjusting translation parameters and packaging configurations within the same processing architecture, allowing versatile multi-format support while keeping the underlying system structure relatively simple.
4Measurement precision
If caption data is synchronized with transcoded video, then viewing accuracy is improved, but synchronization errors occur during frame rate changes
Solution Approach 1:
The system performs preliminary actions to calculate and apply correct time offsets for caption data based on the input video's frame rate and duration. By pre-computing these synchronization parameters before transcoding, the system can accurately re-synchronize caption data with the output video even when frame rates change, maintaining both precision and stability.
Data Source
AI summary
Methods of preserving captioning information in an input video stream through transcoding of the input video stream include extracting caption data from the input video stream, translating the caption data into at least one output caption format, packaging the translated caption data into data packets for insertion into a video stream, synchronizing the packaged caption data with a transcoded version of the input video stream, receiving a preliminary output video stream that is a transcoded version of the input video stream, and combining the packaged caption data with the preliminary output video stream to form an output video stream. Related systems and computer program products are also disclosed.