VoIP

Webcams 3: USB 2.0 Friend or Foe?

Logitech-C910-WebcamHave you ever noticed that basically all webcams are connected to the host computer using the USB 2.0 bus? The ubiquitous USB 2.0 bus is cheap and convenient for such purposes. Providing 480 Mbps it’s no slouch, but it’s not exactly state-of-the-art either. This has implications when webcams are reaching for HD resolutions at decent frame rates.

Until quite recently webcams always provided an uncompressed image stream to the host computer. USB 2.0 is a serial connection standard supporting up to 480 Mbps. That’s about one third of the data rate of the production HD-SDI standard, SMPTE-292M, which is 1.485 Gbps.

Let’s do a little math corresponding to a 720p video stream as related to uncompressed HDTV.

8 bit/pixel @ 1280 x 720 @ 59.94fps = 105 MB per/sec, or 370 GB per/hr.

105 MB/s = 840 mbps

…but a lot of video conferencing gear actually uses 30 frames/second instead of 59.94 or 60 frames/second…so half that value…

720p30 = 420 mbps!

There you have it! The mathematics supports the assertion that 720p30 uncompressed “HD” video stream can be passed across the USB 2.0 serial bus. This explains how Skype, Google, ooVoo, VSee and others have been able to offer HD video using common USB 2.0 connected webcams. Understanding the limit of the USB 2.0 connection also informs us why 1080-capable webcams have not become similarly commonplace.

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Remote Conference Presentation via WebRTC

BlogGeekMe-ScreenshotCredit is due to Tsahi Levent-Levi of Amdocs, not only is he a leading voice in the evolution of WebRTC, but he’s eating that very dog food himself. It’s so great to see people walk-the-walk while giving-the-talk. That is in fact what he’s planning to do.

In a blog post today he put out a call for suggestion of WebRTC-based services to highlight in giving a presentation to a conference. His plans include giving the presentation remotely via a WebRTC connection. That’s awesome.

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Video Calling 3: Brightlines I/S-22 LED Conference Lamp

i-Series-with-desk-clamp1 copyIt’s been a month or more since I took delivery of a Brightlines I/S-22 light for use in my working life. I noted it’s arrival to my small circle of associates, who seem to be happy with the result. With the I/2-22 providing even fill lighting I’ve not appeared as a disembodied head on any video calls.

As was mentioned previously, the I/S-22 has three possible mounting options; a VESA bracket with a 6” gooseneck, a table clamp with a 22” long gooseneck, or a heavy round base with that same 22” gooseneck.

The VESA mount allows the light to be  mounted to the back of a monitor, presuming that the monitor is not itself mounted to a VESA type arrangement.

My situation seemed best addressed by the long gooseneck with the table clamp. This allows me to mount the light to the edge of the table immediately behind the HDX-4500. The HDX is a large and rather heavy device, and does not have VESA type mounting holes. Happily the I/S-22 on the long gooseneck rises to an appropriate height, about 4 inches above the top of the HDX.

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Living With Technology: Sennheiser DW Pro2

It’s been just over two years since the Sennheiser DW Pro 2 DECT headset arrived. It’s been a very reliable device, seeing almost daily use over that period. This past weekend I had to effect a small repair. The issue was very minor, but worth noting if you own a similar device.

The DW Pro2 headset returns to its desktop base for charging when not in use. Normally it connects to the base in a firm manner, the blue LED on the earpiece indicating a charging state.

I had noticed that a couple of times that it wasn’t quite so firm in how it was received by the desktop base. If I wasn’t careful the headset would appear to be on the base, but the blue LED would not light and it would not charge. The upshot being that the next day when I went to use the headset it would not be fully charged.

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Mix-Master Mike*: Bridging The Bridges Then & Now

Mocet-Communicator-White-VUC-Composite copyDo you remember way back when VUC calls were don using Talkshoe? That was the service that Randulo used to create the VUC, and it remained the primary conference  used until the end of 2008. It was in November 2008 that I arranged to have David Frankel of ZipDX make a VUC guest appearance.

David’s visit was unusual in that we used it as an opportunity to expose the assembled audience to conferencing using HDVoice. David was kind enough to provide some licenses for Counterpath’s G.722-capable Eyebeam soft phone. This allowed us to have a dozen people on ZipDX in HDVoice, while the rest of the audience remained on Talkshoe. You can still listen to the archived recording of the call if you’d like.

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