Media File Descriptor Separation for Low-Latency Live Recording
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Solution Overview
Problem
Existing media file formats like ISOBMFF face challenges in live recording scenarios due to incomplete file structures and high latency in reading media files, especially when the file length is unknown, leading to potential data loss and delayed consumption.
Innovation Solution
The use of a descriptor file alongside the media file to enable continuous writing and reading of media elements, allowing for low-latency access by periodically or ad hoc updating the descriptor file with playback information, even before the media file is fully written.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the entire file structure is required to be complete before reading, then data integrity is ensured, but reading latency increases and live recording capability is compromised
Solution Approach 1:
The patent divides the media file into two separate components: a descriptor file containing metadata and indexing information, and a media file body containing the actual media data. This segmentation allows the descriptor file to be read independently to obtain information about media elements without requiring the entire media file body to be complete, thus reducing reading latency while maintaining data integrity through the use of descriptors that track media element locations and properties
Solution Approach 2:
The descriptor file is written and updated in advance during the media recording process, containing preliminary information about media elements before the complete media file is available. This preliminary action enables readers to access descriptor information and understand media element structure, locations, and properties without waiting for the entire media file to be written, thereby reducing latency while ensuring data integrity through the preliminary descriptor information
2Productivity
If the file structure is updated continuously during live recording, then immediate availability for consumption is achieved, but file structure completeness deteriorates
Solution Approach 1:
By separating the descriptor file from the media file body, the patent enables continuous updates to the descriptor file during live recording without requiring the entire file structure to be complete. The descriptor file can be updated independently with new media element information as it becomes available, providing immediate availability for consumption while the media file body continues to be written, thus resolving the contradiction between continuous updates and structure completeness
Solution Approach 2:
The descriptor file acts as an intermediary between the incomplete media file body and the reading process. It provides a stable interface that contains all necessary information about media elements, allowing readers to access media information without requiring the complete media file structure. This intermediary enables continuous updates during live recording while maintaining apparent structure completeness for readers
3Loss of time
If a separate descriptor file is maintained alongside the media file, then reading latency is reduced, but system complexity increases
Solution Approach 1:
The patent extracts the descriptor information from the traditional monolithic media file structure and places it in a separate descriptor file. This extraction reduces reading latency by allowing independent access to descriptor information without reading the entire media file body. While it introduces an additional file, the complexity is managed through standardized descriptor formats and clear relationships between descriptors and media elements, making the system complexity acceptable compared to the benefit of reduced latency
Data Source
AI summary
A method of writing a media file comprises writing a media file which includes a file header, a file body for containing media elements, and a descriptor portion enabling reading of the media elements in the body portion. Further, the file header includes data enabling the location of the file's descriptor portion to be determined. Also disclosed herein is a method of reading a media file stored on a data storage media. There is also disclosed a method of live recording of media.