Wireless Display Back Channel Using Timestamped Input Packets
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Solution Overview
Problem
Current wireless display systems lack efficient methods for bidirectional communication between wireless source and sink devices, particularly in transmitting user input data from sink devices to source devices, which limits user control and seamless media sharing experiences.
Innovation Solution
The system enables wireless sink devices to transmit user input data to source devices by generating data packets with timestamp flags and payload data, allowing for synchronized audio and video control through a communication session, using processors and memory to execute instructions for packet generation and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wireless display systems use unidirectional communication from source to sink devices, then system simplicity is maintained, but user control capability and bidirectional interaction are limited
Solution Approach 1:
The data packet structure is segmented into distinct components: packet type identifiers, timestamp fields, and payload sections. This segmentation allows the system to implement complex bidirectional communication with precise timing control while maintaining clear protocol structure and ease of processing at each device端
Solution Approach 2:
A standardized packet format acts as an intermediary structure between source and sink devices, enabling bidirectional communication through a well-defined protocol. The packet includes type fields that differentiate between control commands and media data, timestamp fields for synchronization, and payload sections for actual content, allowing versatile interaction without requiring complex device-specific protocols
2Measurement precision
If timestamp fields are always included in data packets, then synchronization precision is improved, but data transmission efficiency and bandwidth utilization deteriorate
Solution Approach 1:
The timestamp field inclusion is made dynamic through a flag mechanism in the packet type structure. The sink device sets the timestamp flag based on whether synchronization data is available and needed, allowing the protocol to adapt between modes: including timestamps when precision is critical (e.g., audio-video synchronization) and excluding them when bandwidth efficiency is prioritized (e.g., static content or low-latency control commands)
Solution Approach 2:
The packet structure parameters are changed conditionally based on content type and synchronization requirements. The packet type field serves as a parameter indicator that tells receiving devices how to interpret the packet structure, whether to expect timestamp fields, and how to process the payload, enabling flexible adaptation between precision and efficiency modes
3Measurement precision
If comprehensive data packets with all control information are transmitted, then user control precision is improved, but communication overhead and processing complexity increase
Solution Approach 1:
The protocol extracts only the essential control information needed for specific operations rather than transmitting comprehensive device state data. Control packets contain targeted fields for specific actions (play, pause, seek, volume) with precise parameter values, eliminating unnecessary data while maintaining full control capability through the packet type system that defines required fields for each control operation
Data Source
AI summary
As part of a communication session, a wireless source device can transmit audio and video data to a wireless sink device, and the wireless sink device can transmit user inputs received at the wireless sink device back to the wireless source device. In this manner, a user of the wireless sink device can control the wireless source device and control the content that is being transmitted from the wireless source device to the wireless sink device. As part of transmitting user input to the source device, the sink device can generate a data packet with a data packet header that includes a timestamp flag indicating the presence of a timestamp field, and the source device can process the data packet based on a timestamp in the timestamp field.