DisplayPort Descrambler Self-Synchronization via Dummy Bytes
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Solution Overview
Problem
Current DisplayPort synchronization processes are inefficient, leading to significant delays that result in visually unacceptable artifacts such as bleaching and flashing, as they rely on infrequent Scrambler Reset signals, which can exceed 16 milliseconds, affecting the quality of audio/visual content transmission.
Innovation Solution
The implementation of self-synchronization methods using encoded values within the data stream, such as dummy bytes in the blanking lines, to rapidly synchronize the scrambler state, reducing synchronization times by leveraging the higher frequency of these values compared to Scrambler Reset symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Scrambler Reset signals are used for synchronization, then synchronization is achieved, but synchronization time exceeds acceptable levels (over 16 milliseconds) causing visual artifacts
Solution Approach 1:
The patent applies preliminary action by embedding synchronization information (dummy bytes with known values) in advance within the video data stream during normal transmission. This allows the receiver to prepare for synchronization continuously rather than waiting for periodic Scrambler Reset signals, thereby reducing synchronization delay while maintaining accuracy.
Solution Approach 2:
The patent introduces an intermediary mechanism - dummy bytes with predictable values embedded in the video stream - that mediates between the scrambled data transmission and the synchronization requirement. These dummy bytes serve as reference points that help the receiver align its descrambler without requiring full Scrambler Reset signals, thus reducing synchronization time.
2Speed
If Scrambler Reset signals occur frequently, then synchronization speed improves, but messaging overhead increases
Solution Approach 1:
The patent applies self-service by making the video data stream itself carry synchronization information through embedded dummy bytes. The existing data stream serves dual purposes: transmitting video content and providing synchronization references, eliminating the need for separate synchronization messages and reducing overhead while improving synchronization speed.
Solution Approach 2:
The patent makes the data stream universal by enabling it to perform multiple functions simultaneously: video data transmission and synchronization reference provision. The dummy bytes embedded in the stream serve both as part of the video content and as synchronization markers, allowing frequent synchronization without increasing messaging overhead.
3Object-affected harmful factors
If synchronization time is reduced below 16 milliseconds, then visual quality improves, but existing synchronization mechanisms become insufficient
Solution Approach 1:
By preliminarily embedding dummy bytes with known values in the video stream at regular intervals, the system prepares synchronization references in advance. This allows the receiver to quickly realign its descrambler within milliseconds by detecting these predetermined patterns, achieving visual quality improvement without requiring complex external synchronization mechanisms.
Solution Approach 2:
The patent implements feedback by having the receiver detect dummy bytes with predictable values in the incoming stream and use this information to adjust and verify its descrambler state. This closed-loop feedback mechanism enables rapid synchronization (under 16 milliseconds) by continuously monitoring for these reference patterns and correcting alignment deviations, thereby eliminating visual artifacts.
Data Source
AI summary
Methods and apparatus for enhanced synchronization of a descrambler, such as used in a signal interface that carries scrambled data. In one embodiment, the descrambler self-synchronizes to a scrambled bit stream (rather than receiving an external “sync” trigger), thereby allowing for much more rapid synchronization. This is accomplished in one variant by identifying a scrambled symbol that has an expected value, predicting an internal scrambler seed based on the expected value, and verifying the predicted seed. For example, an invention-enabled device can synchronize to a DisplayPort stream during blanking intervals which are filled with known “dummy” bytes. Blanking intervals are much more frequent than explicit synchronization symbols, thus an invention enabled device can greatly improve synchronization times, and eliminate e.g., visual artifacts.