In a USB 3.0 world, it may be difficult to rely on USB 2.0 extensions. After all, you always want to be up to date and take advantage of the technological innovations that the market offers. However, USB 2.0 extensions can still be beneficial.
(Image: SDVoE Alliance)
Contents of this basic article:
- USB 2.0 vs. USB 3.0 with limited bandwidth
- Collaboration und Conferencing
- 4K, 6K and 8K cameras
- 6K image sensors in the conference room
- Range with USB-C
Tavis Sparrow, Senior Technical Business Manager at Icron, explains why USB 2.0 expansions make sense in a USB 3.0 world and what that can look like in theory in his workshop held at InfoComm 2022.
“We often talk to engineers and designers about this topic. “You have new USB 3.0 widgets that you want to use, but some signals have to be extended,” explains Sparrow. There is often a desire to do this in the USB 3.0 domain in order to be able to offer the entire bandwidth in a single expansion solution.
USB 3.0 is often seen as the standard for connecting devices, particularly high-bandwidth cameras, high-resolution cameras and multi-channel audio devices, as well as content recording via platforms such as Google Meet Rooms. The devices must be connected using cables.
It is important to pay attention to where you place the respective boxes so that they are within the limited cable range. Extensions can help here.
USB 2.0 vs. USB 3.0 with limited bandwidth
The higher the resolution, the higher the frame rate and the more audio channels, the more bandwidth is required. SDVoE, for example, uses 10Gb networks for AV experiences with up to 8K for multilink applications. According to Sparrow, it is a challenge not to exceed the 9 Gbit of the network: “USB 3.0 (Gen 1), probably the most common SuperSpeed connection for cameras that support up to 4K streaming content, runs at 5 Gbit . So the dilemma is that when trying to implement USB 3.0 expansion on the SDVoE network, the upper limit is around 14 Gbits. That won’t work.” The solution: With USB 2.0. only half a gigabit is required in addition to the 9 Gbit SDVoE payload. In this way, the 10 Gbit limit is not exceeded.
Fig. 01 uses the example of cameras and audio devices to illustrate which USB speed (USB 1.1, 2.0 or 3.0) is required to enable the intended connections. On the video level, everything up to 1080p can be served with a USB 2.0 connection. If you exceed 1080p, you need a speed of 5 Gbit, which you can achieve with USB 3.0. For audio devices, the “USB 2.0 limit” does not even have to be exceeded – for microphone and stereo transmissions, even USB 1.1 speed is sufficient.
Collaboration und Conferencing
“Most clients and platforms achieve 720p resolution on a good day,” estimates Tavis Sparrow. This statement applies at least to streaming content. Higher resolutions are also possible for static images and shared use of the desktop, but the focus at this point remains on the camera. Microsoft Teams can also achieve 1080p in the right situation, but USB 2.0 is also good here. “We don’t need USB 3.0 to get these results out of clients. (…) Even if you have a camera that transmits 4K to the soft codec, everyone else in the audience will see it at 720p resolution.”
4K, 6K and 8K cameras
It is probably a bit premature to conclude from what we have learned so far that you should only use USB 3.0 solutions for 4K, 6K and 8K cameras. It should be briefly described what these terms actually mean. “We often use the terms (…) to communicate a certain level of performance of a particular product,” says Sparrow. In many cases with 4K and 6K, it’s not about the content that comes out of a camera, but about the image sensor in the camera itself. “Especially cameras that have AI or ML functions where the processing takes place in the camera head, use a large image sensor, run their analysis and algorithms, and then output something that is often much lower resolution than the 1080p range,” Icron’s Senior Technical Business Manager further explains. These 4K and 6K image sensor cameras can work with a USB 2.0 interface. As far as output resolution in the UCC range is concerned, there is a small family of cameras that can output 4K, and the number is increasing. USB 3.0 SuperSpeed with 5 Gbit is more suitable for these cameras.
8K often involves DSLR cameras (Digital Single-Lens Reflex). While these cameras can record 8K, they do not transmit 8K videos to the USB ports, at most 4K. Otherwise, they do this via a USB 3.0 or HDMI interface – 8K streaming from these devices themselves is currently not possible.
6K image sensors in the conference room
AI cameras work with a large image sensor. After processing and intelligent framing, you can then output 1080p, part of this image tensor, as content from the port (see Fig. 03). Simply put, according to Tavis Sparrow, this is a digital Canon zoom function without pixelation.
You can also use a 6K image sensor for auto-framing in the conference room, although the actual resolution in this variant is lower, as you can see in Fig. 04. A USB 2.0 solution should be sufficient here.
Range with USB-C
And how do you get the content out of a USB 3.0 camera? Normally you only have one or two meters of leeway for this. According to Sparrow, the number of USB 3.0 cameras is currently growing – especially those that end in Type-C and have an included cable. Some of these kit cables can be up to 5m long. “To someone who doesn’t look behind the curtain, it looks like an exceptionally long cable that they can’t get anywhere else. What actually happens there? Well, these Type-C cables are designed to be suitable for USB 2.0 traffic only. So when the host connects to those same USB 3.0 cameras, it can only work with a USB 2.0 communication path. And this camera now runs in USB 2.0 fallback mode at 720p and 1080p via that long Type-C cable. With these long cables, there is no USB 3.0 communication,” explains Sparrow.
In summary, it can be said that USB 2.0 expansions can go hand in hand with the newer USB 3.0 technology if you only have limited bandwidth capacities available. Tavis Sparrow emphasizes: “USB 2.0 does not represent a compromise in the area of extension.”
// (15324)
Source: www.professional-system.de
