This common behavior occurs because your camera system intelligently uses different video streams—specifically, the Main Stream for single, full-screen views and the Sub Stream for simultaneous multiple camera displays.
When you view a single camera in full screen, your system is typically displaying the camera's Main Stream. This stream is designed for the highest possible quality, offering maximum resolution, frame rate, and detail. It's ideal for detailed monitoring or reviewing footage, but it requires substantial network bandwidth and processing power.
Conversely, when you view multiple cameras simultaneously (e.g., in a grid layout on a monitor, NVR, or mobile app), the system defaults to displaying the Sub Stream for each camera. The Sub Stream is a lower-resolution, lower-frame-rate version of the video feed.
Understanding Video Streams
To clarify this distinction, consider the differences between these two primary video streams:
| Feature | Main Stream (High Quality) | Sub Stream (Lower Quality) |
|---|---|---|
| Primary Usage | Single camera, full-screen display; primary recording | Multiple camera grid display; remote viewing; mobile apps |
| Video Quality | High resolution, high frame rate (best fidelity) | Lower resolution, lower frame rate (good for overview) |
| Bandwidth Needs | High | Low |
| System Load | Higher processing and network demands | Lower processing and network demands |
| Purpose | Detailed viewing, high-quality recording | Efficient multi-view, smooth performance, remote access |
Why This Design Choice?
This dual-stream architecture is a deliberate design to optimize performance and resource management:
- Resource Efficiency: Displaying multiple high-quality (Main Stream) videos simultaneously would place an immense burden on your network bandwidth, the processing power of your viewing device (NVR, DVR, PC, smartphone), and even the cameras themselves. Imagine trying to stream eight 4K Main Streams at once—it would quickly overwhelm most typical networks and devices.
- Smooth Performance: By utilizing lighter Sub Streams for multi-camera views, the system can ensure faster loading times, smoother transitions, and prevent lag or dropped frames, even on networks with limited bandwidth. This provides a more responsive and stable monitoring experience.
- Remote Accessibility: Sub Streams are also commonly used for remote viewing on mobile devices, where bandwidth can be inconsistent, and lower quality is acceptable for quick checks.
Potential Issues and Solutions
If you are experiencing a situation where you can view your camera in full screen but not in a multi-camera group, it often points to an issue with the Sub Stream specifically.
- Sub Stream Configuration: The most common reason is that the Sub Stream on your camera or recorder might be disabled, incorrectly configured, or set to an unsupported resolution/encoding.
- Solution: Access your camera's or NVR's web interface or configuration menu. Navigate to the video encoding settings and ensure the Sub Stream is enabled and set to a standard, lower resolution (e.g., 640x480 or 320x240) and a reasonable frame rate.
- Network Bottlenecks: While Sub Streams use less bandwidth, an extremely congested or unstable network can still prevent them from displaying properly.
- Solution: Verify your network stability. Ensure your viewing device has a strong, stable connection.
- Software or Device Compatibility: Sometimes, the viewing software or device might have trouble decoding the specific Sub Stream format.
- Solution: Ensure your NVR/DVR firmware and viewing software are up to date. Try viewing from a different device or client application if possible.
- Camera Hardware Limitations: In rare cases, very old or low-end cameras might have limited Sub Stream capabilities or buggy implementations.
- Solution: Check the camera's specifications and consider firmware updates.
Understanding the difference between Main and Sub Streams helps diagnose and resolve common video display issues, ensuring you get the most out of your camera system. For more general information on how video streaming works, you can explore resources like this guide on Understanding Video Stream Basics.
