Windows Media Video Redirector Guide

The Windows Media Video Redirector is a crucial component for optimizing the delivery of multimedia content, particularly video, within remote desktop and virtual desktop infrastructure (VDI) environments. It plays a significant role in ensuring a smooth and high-quality user experience by offloading video processing from the remote server to the client device. Understanding this technology is essential for administrators seeking to provide efficient remote access to applications and desktops that involve video playback.

Without proper redirection, playing video in a remote session can consume substantial server resources and network bandwidth, leading to stuttering, low-quality playback, and a poor user experience. The Windows Media Video Redirector addresses these challenges by intelligently routing video streams directly to the client for rendering, leveraging the client’s local hardware capabilities.

Understanding Windows Media Video Redirector

The Windows Media Video Redirector, often referred to as WMVR, is a feature designed to improve the performance of Windows Media content when accessed through Remote Desktop Services (RDS) or VDI. Instead of the server rendering the video and sending it as a series of screen updates, WMVR allows the raw video stream to be sent to the client. The client then decodes and renders the video locally.

This redirection mechanism significantly reduces the processing load on the remote desktop server. It also optimizes network traffic, as raw video streams can often be more efficiently transmitted than a constant stream of graphical updates representing the video frames. This approach is particularly beneficial for high-definition video content and environments with numerous concurrent remote users.

How WMVR Enhances Performance

The core benefit of the Windows Media Video Redirector lies in its ability to shift the computational burden. Here’s a breakdown of how it works:

Client-Side Rendering: When a user plays a Windows Media file in a redirected session, the server identifies the media stream. Instead of processing it, the server instructs the client to play the media file directly.
Optimized Network Traffic: The video data is often sent in its original compressed format, or a highly optimized format, directly to the client. This bypasses the need for the server to decompress, render, and then re-compress the video into a display protocol stream.
Reduced Server Load: By offloading decoding and rendering, the remote desktop server conserves CPU and GPU resources. This allows the server to handle more concurrent user sessions or dedicate its resources to other critical tasks.
Improved User Experience: The result is smoother video playback with higher frame rates and better visual quality, making the remote experience feel more native.

Prerequisites for Implementing WMVR

For the Windows Media Video Redirector to function correctly, certain prerequisites must be met on both the server and client sides. Ensuring these conditions are in place is crucial for successful deployment and optimal performance.

Server-Side Requirements

On the Remote Desktop Session Host (RDSH) or virtual machine acting as the remote desktop, the necessary components for Windows Media redirection must be installed and enabled. This typically involves:

Remote Desktop Services Role: The RDSH role must be properly configured on the server.
Windows Media Player: While not always directly used for playback on the server, the underlying Windows Media codecs and components are often required for the server to recognize and facilitate the redirection of media streams.
Group Policy Configuration: Specific Group Policy settings may need to be enabled to allow Windows Media redirection.

Client-Side Requirements

The client device connecting to the remote session also has specific needs for the Windows Media Video Redirector:

Remote Desktop Connection (RDC) Client: The client software (mstsc.exe) must support Windows Media redirection. Modern versions of the RDC client typically include this support.
Windows Media Player or Compatible Codecs: The client machine must have Windows Media Player or compatible codecs installed to be able to decode and play the redirected video stream locally.
Sufficient Client Resources: The client device needs adequate CPU, RAM, and graphics capabilities to smoothly play the video content it receives.

Configuring Windows Media Video Redirector

Configuring the Windows Media Video Redirector primarily involves setting up Group Policy on your server infrastructure. These settings dictate whether redirection is allowed and how it behaves.

Using Group Policy

Group Policy is the primary method for enabling and managing Windows Media redirection. You can configure these settings in a domain-level Group Policy Object (GPO) linked to your RDSH servers or directly on the local Group Policy of individual servers.

Open Group Policy Management Editor: Navigate to Computer Configuration > Policies > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Device and Resource Redirection.
Enable Windows Media Redirection: Locate the setting ‘Allow Windows Media Player multimedia redirection’. Set this policy to Enabled.
Apply Changes: After enabling the policy, ensure it’s applied by running gpupdate /force on the server or waiting for the next Group Policy refresh cycle.

Additionally, within the same Group Policy path, you might find other relevant settings that can influence media redirection performance or behavior. Reviewing these options can help fine-tune your environment.

Remote Desktop Connection Client Settings

While server-side Group Policy is crucial, client-side RDC settings also play a role. When connecting via mstsc.exe, ensure that multimedia redirection is enabled:

Local Resources Tab: In the Remote Desktop Connection dialog, go to the Local Resources tab.
Remote Audio and Video: Under Remote audio and video, ensure that the option for Play on this computer or similar is selected. This ensures that the client is prepared to handle redirected media.

Troubleshooting Common WMVR Issues

Even with proper configuration, you might encounter issues with the Windows Media Video Redirector. Here are some common problems and their potential solutions.

Video Not Redirecting or Playing Poorly

Verify Group Policy: Double-check that the ‘Allow Windows Media Player multimedia redirection’ policy is indeed enabled and applied correctly on the server. Use gpresult /h output.html to verify applied policies.
Client Codec Support: Ensure the client machine has the necessary codecs to play the specific video format. If the video plays locally on the client but not through redirection, it might indicate a codec mismatch or missing codec on the client.
RDC Client Version: Confirm that both the server and client are using up-to-date Remote Desktop Connection client versions. Older clients might not fully support WMVR.
Network Latency and Bandwidth: While WMVR optimizes network usage, extremely high latency or insufficient bandwidth between the client and server can still impact performance. Test your network connectivity.
Firewall Settings: Ensure that no firewalls (on either client or server) are blocking necessary communication ports for multimedia redirection, although this is less common for WMVR itself as it operates within the RDP protocol.

Audio/Video Sync Issues

Occasional audio and video synchronization problems can occur. This is often related to network conditions or client processing power. Try:

Updating Client Drivers: Ensure display and audio drivers on the client machine are up to date.
Reducing Video Quality: If possible, try playing a lower-resolution video to see if the issue persists. This can help isolate whether the problem is resource-related.

Conclusion

The Windows Media Video Redirector is an indispensable tool for delivering a superior multimedia experience in remote desktop and VDI environments. By understanding its principles, carefully configuring the necessary settings, and proactively troubleshooting potential issues, administrators can significantly enhance user satisfaction and optimize their infrastructure. Implementing WMVR effectively ensures that remote users enjoy smooth, high-quality video playback, making their virtual workspace as productive and engaging as a local one. Take the time to properly set up and monitor your Windows Media Video Redirector configurations to unlock its full potential and provide a seamless remote experience for all your users.