When can USB 2.0 actually be better than USB 3.0? Video Capture!

This has come up a lot recently and it’s a little counter-intuitive. There are times when an older video capture device, using USB 2.0, is actually better than new new one that leverages faster USB 3.0 or 3.1. The reason is simple, but not obvious.

Just a few years ago, USB-attached video devices had to cope with the constraints of USB 2.0 (480 mbps) so they often incorporated on-board scaling and compression engines. Remember that using uncompressed video USB 2.0 maxes out at 720p30. This is why that was, and remains, the de facto standard for video chat applications.

Their newer kin, with a faster USB 3.0 (5 Gbps) connection to the host, can pass an uncompressed 1080p60 video stream…so they usually don’t have as much on-board processing capability.

Consider as an example the El Gato family of HD60, HD60S and Cam Link USB capture devices. The first two of these devices look very similar, but the differences are substantial and potentially important.

El Gato HD60

We used an HD60 at Cluecon 2017 when we needed a last minute way to ingest an HDMI source into a computer. It worked really well. It has a USB 2 connection to the host. It could deliver YUY2 uncompressed up to 720p30. It could deliver 1080p30 using MJPEG or H264 compression. MJPEG has zero latency, so this is the preferred way to accommodate 1080p over a USB2 link. The UVC 1.1 standard, circa 2005, indicates as much.

While conceptually it was a UVC compliant device, the HD60 has a device-specific installable driver. This driver was installed with the El Gato Game Capture utility, which we used to verify the correct operation of the device.

El Gato HD60S

The newer HD60S looks so very similar. The primary difference being the USB 3 Type-C connection to the host. USB-C ports still being less common, many people would likely use a type-C to type-A cable to connect it to a USB 3.0 port.

The HD60S is capable of 4K60 capture (!) but does not have an onboard compression engine. So the capture or streaming application must cope with uncompressed video. That also means that when connected to an older host via USB 2.0 it’s only capable of 720p30.

If the host computer is resource constrained (no USB 3) the ability to deliver compressed video over the USB link can be a very real benefit. Similarly, an onboard scaler allows a capture dongle to accept 1080p60, while delivering 720p to the client application. There are times when this is also valuable. Typically, when you must use a client application that insists upon a particular video format, but the source delivers something else entirely.

El Gato Cam Link

These various considerations are why El Gato’s USB 3.0 connected Cam Link (reviewed previously) can be so cheap. It does essentially no onboard video processing.

That’s great if it does what you need. I used one at ClueCon 2018 to capture the 1080p60 stream from a BlackMagic ATEM switcher into my vMix host.

My i7-powered Airtop-PC is quite powerful and vMix is massively flexible, so the limitation of the Cam Link were not a factor. However, Cam Link not especially flexible. The older, USB 2.0 connected HD60 is actually more useful.

Update: A couple of people have refuted my claim that there can be an advantage to USB 2 capture devices over USB 3. I accept that the headline is a little click-baity. My intention was to highlight the fact that the new generation of USB 3 capture device did not do something that their older, USB 2 predecessors made commonplace. As a result, if you have an older, slower and/or I/O constrained host you might find that the new and supposedly better capture devices put you at a disadvantage.

How-To: Using an RTSP Stream as a Source for a WebRTC application

This post arises from a question posed by someone via Quora. I’m not all that engaged with that Q&A platform, but this question seemed novel, so I offered an answer. I thought the answer worth sharing in a little more depth, so I offer it here as well.

The question was, “How can I use the RTSP stream from an IP camera as a source for a WebRTC application?”

There are two parts to solving this puzzle; (1) Connect to the RTSP stream and (2) Make it appear like a webcam to the client application.

Obvious Answer: vMix

At the outset, let me say that I would address this using vMix. vMix solves both parts of the puzzle handily. If this is all that you needed to achieve, the $60 Basic HD license would suffice.

Of course, you’d need to learn a little about the application, which is deep. To my mind it’s fun, but some might find it daunting. Further, vMix requires a considerable host platform. You’re not going to run it on trivial hardware.

Let’s just say that we’d like to solve the problem with less spending and requiring less knowledge overhead.

Less Obvious Answer: VLC & NDI Tools

VLC is the ubiquitous, open source media player. Available on all platforms it can play anything I’ve every wanted to open. Beyond files, it can open network streams. I’ve used it to listen to my local PBS radio station. I’ve also used it to watch video streams from our Grandstream surveillance cameras, as shown below.

VLS viewing RTSP stream

NDI stands for Network Device Interface. It’s a network protocol, developed by Newtek of TriCaster and Video Toaster fame, that allows low-latency, lightly compressed video to be passed over a gigabit Ethernet network. NDI is impressive, but I won’t wax poetic about that here.

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Logitech’s Brio 4k Webcam Pro

There’s a new webcam in the house…errr…home office! Yes, I have received a sample of Logitech’s latest, the Brio 4K Webcam Pro.

Even before the sample arrived I had a great conversation about the Brio with Dave Michels. Dave captured that discussion for publication on his blog.

I’ve put the Brio through a few simple experiments and learned a few things. At least superficially, it does what it says. Connected via USB 3.0 it delivers a 2160p30 (aka 4k) stream using MJPEG encoding to vMix and OBS.

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Online Marketers: How-To Hold Branded Blabs

OnSip-SMBlabLong-time VUC sponsor OnSIP has been running a series of video chats they call #SMBLAB. Blab is a newer, kinda Hangout-like video chat tool built using WebRTC. This week I participated in one with Mike Oeth, CEO of OnSIP, Angela Leavitt of Mojo Marketing, and Randy Resnick, founder of the VUC.

Blab is dead simple to use. It integrates with Twitter for user authentication, allowing up to four people to join each Blab (call?)  The resulting video chats are recorded. Throw in good social media integration and you can see why it’s an online marketers dream.

As nice as blab is, it’s visual presentation is a bit generic. It doesn’t have the image overlay or lower-third capability that you find in Hangouts. That means that you can’t readily add your name or company logo.

That said, it doesn’t need to be this way! You can take matters into your own hands and deliver strong, visually branded blabs…if you want to. It takes a little effort in advance, but it’s not difficult…and it will strengthen your brand presentation.

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Tip: Faking an HDMI Connection

FITPC-HeadlessLast week I once again saw a need to share the output of an Android device. As I’ve described previously, this requires the use of an HDMI splitter to feed both a monitor and the HDMI capture card in my vMix PC. The monitor satisfies that HDCP handshake, which allows the PC to see the video stream.

However, there are times when it’s just not convenient or practical to have an extra monitor involved. This came up recently in a thread in the Wirecast support forum. Someone wants to capture the screen of a number of Mac Mini’s in order to bring multiple Skype video calls into a streaming production. They run the Mac Mini’s headless, accessing the Mac desktops using a software screen sharing application.

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Observations of the vMix 17 Public Beta

Last week saw the release of the vMix Fun Time Live Show for March which was punctuated by the public release of a beta preview of vMix 17. The official release of vMix is being timed to coincide with the annual NAB Convention, which is April 16-21 in Las Vegas.

In the middle of 2015 vMix replaced Wirecast as my preferred desktop video production software. vMix is effectively a production switcher. It allows me to combine various audio and video sources in real-time, the results being sent to a Hangout-On-Air or recorded to disk. It handles webcams, graphics, animations, video capture cards, live desktop capture and even PowerPoint files with ease. Further, it does so while being less hardware intensive than its competition.

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