Source Picture Timing Signaling for Accurate Video Frame Synchronization
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Solution Overview
Problem
Existing video coding standards like ITU-T H.264, ITU-T H.265, and ITU-T H.266 lack efficient mechanisms for signaling source picture timing information, which is crucial for accurate decoding and display of video content.
Innovation Solution
The proposed techniques involve parsing syntax elements in a source picture timing information message to determine the presence and value of a scale factor for determining the source picture interval, using a variable set to 0 when a specific element is absent, to facilitate accurate timing information signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If video coding standards use traditional signaling mechanisms for picture timing information, then the decoding process can be simplified, but the accuracy of source picture timing information is insufficient
Solution Approach 1:
The timing information is segmented into multiple syntax elements: spti_source_type_present_flag, spti_source_type, and spti_time_scale. This segmentation allows precise representation of timing information while maintaining structured parsing and processing in the decoding system.
Solution Approach 2:
The signaling mechanism is made dynamic through conditional parsing: when spti_source_type_present_flag equals 1, the decoder parses both spti_source_type and spti_time_scale; when it equals 0, only spti_time_scale is parsed. This dynamic approach adapts the complexity of processing to the actual information present in the bitstream.
2Reliability
If video coding standards signal detailed source picture timing information, then the synchronization accuracy improves, but the bitstream complexity increases
Solution Approach 1:
The spti_source_type parameter uses a 16-bit unsigned integer to represent different source types, while spti_time_scale uses a 32-bit unsigned integer for time scale representation. These parameter changes allow precise encoding of timing information with appropriate bit depths for different levels of precision requirements.
Solution Approach 2:
The source picture timing information message serves multiple functions: it identifies source type (camera, scanner, generator, etc.), provides time scale information, and enables accurate synchronization. This multi-functional signaling structure reduces the need for separate messages for different timing aspects.
3Measurement precision
If the decoder always parses all timing syntax elements, then the timing information completeness is ensured, but the decoding efficiency decreases
Solution Approach 1:
The parsing process is made dynamic through the spti_source_type_present_flag. When this flag equals 1, the decoder parses both spti_source_type and spti_time_scale to ensure complete timing information. When it equals 0, the decoder only parses spti_time_scale, improving decoding efficiency when full source type information is not required.
Solution Approach 2:
The bitstream structure enables self-service decoding where the presence flag automatically guides the parser to extract only the necessary information. This eliminates the need for complex external control logic to determine what timing information to parse, as the bitstream itself provides the guidance.
Data Source
AI summary
A device may be configured to decode video data based on information included in a source picture timing information message. In one example, a source picture timing information message includes a syntax element message specifying a scale factor used in determining the source picture interval of corresponding consecutive pictures in output order. In one example, the scale factor based on a value specified by the syntax element and a variable.