HDMI Transmission Device Gap Packet Switching
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Solution Overview
Problem
The time-consuming fixed rate link (FRL) training process in HDMI transmission systems causes delays when video formats change, leading to an unfavorable user experience due to the need for retraining before resuming video transmission.
Innovation Solution
Incorporating a packetizer circuit with a gap packet generator, video packet generator, multiplexer, and controller in an HDMI transmission device, which allows for continuous gap packet transmission during format changes or signal abnormalities, enabling seamless switching to video packets once data is ready without reperforming the FRL training process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FRL training is performed to ensure accurate data transmission and maximum bandwidth, then transmission reliability is improved, but transmission delay increases due to the time-consuming training process
Solution Approach 1:
The system performs FRL training in advance during the initial connection establishment or format change detection, so that when video format changes occur during operation, the training is already completed and the system can immediately switch to video packet transmission without waiting for retraining. This preliminary preparation eliminates the delay that would otherwise occur during format changes.
Solution Approach 2:
The system maintains continuous video packet transmission by detecting format changes and triggering FRL training in the background without interrupting the video stream. The packetizer circuit continues to send video packets while training occurs, ensuring uninterrupted useful action and eliminating visible switching delays for the user.
2Measurement precision
If FRL training is performed whenever video format changes to maintain transmission quality, then transmission precision is improved, but productivity decreases due to repeated training processes
Solution Approach 1:
The system implements a feedback mechanism where the packetizer circuit continuously monitors video format changes and signal status. When a format change is detected, the system triggers FRL training and then switches to video packet transmission. This feedback loop ensures training is performed only when necessary (upon format change detection) rather than on every potential change, maintaining transmission precision while avoiding unnecessary retraining that would reduce productivity.
Solution Approach 2:
The system changes the operational parameters of the packetizer circuit based on detected conditions - switching from gap packet transmission to video packet transmission after FRL training completes. This parameter change allows the system to maintain high data transmission rate accuracy through targeted FRL training while improving overall video transmission efficiency by resuming normal video packet flow immediately after training without prolonged interruptions.
Data Source
AI summary
An HDMI transmission device includes a packetizer circuit and a processor. A control method of controlling the HDMI transmission device includes performing a fixed rate link training, upon passing the fixed data rate link training, the processor transmitting an initial gap packet generation command to a controller of the packetizer circuit to output a selection signal to the packetizer circuit, so as to output an initial gap packet, when video data is not ready, continuously outputting the initial gap packet, when the video data is ready and a format change of the video data is detected or a signal abnormality unrelated to hot-plugging is detected, the processor transmitting a subsequent gap packet generation command to the controller to determine whether a block boundary is reached, and the controller switching the selection signal upon reaching the block boundary for the packetizer circuit to output the subsequent gap packet.