Mixed Event Message Tracks for DASH Metadata Timing
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Solution Overview
Problem
The ISO/IEC 23009-1 Dynamic Adaptive Streaming over HTTP (DASH) standard does not adequately address the signaling of sparse timed metadata tracks, which can lead to loss of chunk boundaries during fragmentation and defragmentation, making it difficult to preserve timing data and support the requirements of ISO/IEC 14496-12 ISOBMFF tracks.
Innovation Solution
The introduction of mixed event message tracks that combine v0 and v1 event message boxes, along with signaling for their types in a track header, allows for the indication of fixed-size metadata samples, enabling random access and navigation without additional size or index information, and supports the preservation of timing data during fragmentation and defragmentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If sparse timed metadata tracks carry emsg boxes as parts of the metadata samples, then the timing information can be included in the track, but the timing data is lost during fragmentation and defragmentation due to loss of Chunk boundaries
Solution Approach 1:
The patent introduces v0 event message boxes that segment the timing information by associating each event with a specific metadata sample's presentation time rather than relying on chunk boundaries. This segmentation allows timing data to be preserved even when chunks are fragmented or defragmented, as each event maintains its temporal reference to the specific sample it was attached to.
Solution Approach 2:
The patent changes the parameter used for timing reference from chunk-based presentation time to sample-based presentation time. By using v0 event message boxes that reference the presentation time of the specific metadata sample containing the event, the system maintains timing accuracy regardless of chunk boundary changes during fragmentation operations.
2Ease of operation
If timed metadata tracks use variable size samples, then the track can carry flexible metadata information, but finding the location of a specific sample requires parsing all previous samples or having associated index segments
Solution Approach 1:
The patent changes the sample size parameter from variable to fixed for metadata samples. By standardizing the sample size, the system enables direct calculation of sample locations based on sample count and fixed size, eliminating the need to parse previous samples or maintain index segments for navigation purposes.
3Adaptability or versatility
If DASH streaming uses usual variable size samples in timed metadata tracks, then the track can adapt to different metadata lengths, but additional size or index information is required for navigation
Solution Approach 1:
The patent changes the sample size parameter from variable to fixed, which simplifies navigation by eliminating the need for additional size or index information. The fixed sample size allows clients to calculate the location of any sample directly based on the sample counter and fixed size, while still maintaining the ability to carry different metadata content in each sample.
Data Source
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AI summary
Systems and methods for Dynamic Adaptive Streaming over HTTP (DASH) is provided. A method includes: obtaining an event message track including a plurality of event message boxes, the event message track configured to be processed by a Dynamic Adaptive Streaming over HTTP (DASH) client for displaying media content; obtaining an indicator that indicates each type of the plurality of event message boxes in the event message track; and providing the event message track to the DASH client or displaying media content based on the event message track.