UPnP Control Point Remote Playback Notification via State Subscription
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Solution Overview
Problem
In UPnP networks, users controlling media content delivery to remotely located rendering devices are unaware of the progress or success of the playback, leading to potential delays and difficulties in identifying playback issues due to distance and network complexities.
Innovation Solution
A method is introduced where a control point initiates a subscription to a state variable at the rendering device and sets a timer, considering the UPnP action successful if a predefined state transition is recognized before the timer expires, or failing if not, with notifications provided to the user via UI, using IMS/SIP protocol and VPN connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If users control media content delivery to remotely located rendering devices via UPnP network, then media content can be delivered to remote devices, but users are unaware of playback progress or success due to distance and network complexities
Solution Approach 1:
The control point subscribes to state variables at the rendering device to receive feedback about playback status. This feedback mechanism provides the control point with real-time information about whether media content is being played back successfully at the remote rendering device, resolving the information loss problem.
Solution Approach 2:
The control point acts as an intermediary between the user and the remote rendering device. It monitors playback status by subscribing to state variables and relays this information back to the user, serving as a communication bridge that overcomes the distance and network complexity barriers.
2Reliability
If users wait for playback confirmation in remote UPnP delivery, then accurate playback status can be determined, but time delays occur due to network round trip time
Solution Approach 1:
The control point proactively subscribes to state variables at the rendering device before playback begins. This preliminary subscription ensures that playback status information is already being monitored and will be available immediately when playback occurs, eliminating the need to wait for confirmation.
Solution Approach 2:
The control point continuously monitors playback status by maintaining an active subscription to state variables throughout the playback process. This continuous monitoring ensures that playback status information is always available without introducing delays, as the system is already in a state of readiness to detect and report playback outcomes.
3Loss of information
If control point monitors playback status continuously, then accurate notification can be provided, but system complexity increases due to subscription management and timer mechanisms
Solution Approach 1:
The rendering device automatically maintains and updates its own state variables that reflect playback status. The control point simply subscribes to these pre-existing state variables, allowing the rendering device to serve itself by maintaining the information infrastructure, thereby reducing the complexity burden on the control point.
Solution Approach 2:
The control point sets up subscriptions and timers in advance before playback begins. This preliminary configuration allows the monitoring system to be ready and waiting, so that when playback occurs, the system can automatically detect and report status without requiring complex real-time decision-making logic during playback.
4Loss of time
If timer timeout value is set short, then notification delay is reduced, but false failure notifications may occur due to network variability
Solution Approach 1:
The timeout value is dynamically adjusted based on the measured round trip time (RTT) between the control point and rendering device. By setting the timeout to a multiple of the actual RTT, the system adapts to network conditions, ensuring that the timeout is neither too short (causing false failures) nor too long (causing delays).
Data Source
AI summary
A method of controlling a play-out of media content in a UPnP network from a control point, wherein the media content has been delivered from a media server to a remote rendering device. Upon having establishing a UPnP remote access connection between the control point and the rendering device, the control point invokes a UPnP action at the rendering device, in response to a user interaction. The control point also initiates a subscription of a state variable at the rendering device, and starts a timer, which will indicate the time that has elapsed since the initiation of the subscription. The control point will regard the UPnP action as a successful action in case it recognises a predefined state variable transition, prior to the expiry of the timeout value, ors a failed action, in case no such predefined state variable transition has been recognised upon expiry of the time out value. The result of the UPnP action is provided to the user as a notification.