Here's how you can use a high-def video camcorder as a webcam for your home office.
In one of last months’ write-ups, on how to optimally outfit a home-based office for ongoing remote- and hybrid-work purposes, I wrote:
One downside to any webcam is that, regardless of the embedded image sensor’s native resolution and other characteristics, the lens it’s mated to is inevitably a fixed focal length, and its close-focusing capabilities, not to mention its more general optical attributes, tend to be subpar. The one thing I don’t like much about my green screen is that because of its circular shape, I need to sit quite close to the webcam so that the virtual background’s edges and real-world mess beyond them don’t appear in the footage. A camera with an optical zoom lens would address this issue, and I’m prepping to try just such a setup; stand by for more coverage to come on this topic.
The preparation, not to mention the implementation, is now complete. And as previously promised, this write-up aspires to document the results, complete with the inevitable warts and workarounds. Way back in 2008, as those of you who’ve been reading Brian’s Brain for a long time (and have outstanding memories) may recall, I sales-price promoted (and also personally purchased) the Canon VIXIA HV30, one of that manufacturer’s last HDV camcorders:
I’ve admittedly barely used it since then; it’s tape-based, so to-computer footage transfers are tedious, and none of my in-use Macs even have built-in FireWire—i.e., IEEE 1394, also known as “iLink”—connections any longer, although Thunderbolt and other adapters can still bridge that gap. I had also bought (previous to the VIXIA HV30 acquisition) a JVC GR-HD1 first-generation HDV camcorder, which got the lion’s share of what little high-def capture attention I mustered.
Plus, as I mentioned in last November’s holiday gift guide, 4K resolution-capable video cameras (and video-capable smartphones, for that matter) are now mainstream, while HDV is 1080p-max (and non-standard at that…HDV officially only supported the 720p and 1080i HD formats). As I’ve written before, HDV was an impressive technical achievement at the time, considering that its developers figured out how to shoehorn credible high-definition video quality into a standard-definition DV format bitrate payload size. But its time has largely passed at this point.
I was therefore pondering whether to just donate the VIXIA HV30 to charity (I’m holding onto the JVC GR-HD1 for posterity, much as I continue to cling to my Apple G4 Cube and first-generation Intel-based white plastic MacBook, not to mention my Google CR-48 Chromebook) when I remembered the VIXIA HV30’s built-in HDMI output and realized that it at least conceptually represented a significant webcam upgrade. Only one “gotcha” gave me initial pause, however: its HDMI output is 1080i60 (1920 horizontal pixels, 1080 vertical pixels, interlaced, with a 60 fields per second rate), whereas low-priced HDMI-to-USB converters generally only accept progressive-scan inputs (and a limited set of resolution and frame rate options, at that). Elgato thankfully came to the rescue with its Cam Link 4K:
It accepts a range of HDMI video input options, including all-important (for this setup, at least) 1080i60. Whereas the Cam Link 4K normally sells for $129.99-ish, a refurb directly from Corsair will “only” set you back $104.99.
Ikan’s 21” HomeStream stand for the camcorder is hard to find in stock:
Fortunately, I came across an open-box unit for $34.95 at B&H Photo Video. It works like a charm; I’ve got it sitting behind the external display (itself sitting on a stand) connected to my early-2015 13” Apple MacBook Pro, with the camcorder peeking over the top of the display.
More generally, I got everything set up:
Then I turned on the camcorder, connected the other end of the HDMI cable to the Cam Link 4K, and fired up Zoom. Good news: Zoom saw the Elgato device as a distinct camera (“Cam Link 4K”, versus the laptop’s built-in “FaceTime HD Camera” webcam) and I was able to select it. Bad news: I got nothing but a black screen when I tried to use it. Eventually, through trial and error, I stumbled across a methodology that works consistently; keep the camcorder and Cam Link 4K constantly connected to each other, even when the camcorder is off, and plug the Cam Link 4K into the computer when you want to use the VIXIA HV30.
The HDV camcorder has an integrated LCD display, extendable from one side, which can also rotate 180°, thereby showing me the framing, exposure, etc. that the camcorder is capturing even if I’m in front of it versus (in normal usage) behind it. Speaking of framing, the wireless remote control included with the camcorder is handy for making zoom lens focal length adjustments. I’d already learned from preparatory research NOT to put a DV tape in the camcorder, to prevent the VIXIA HV30 from automatically shutting off after a few minutes’ time in record standby mode even if the camcorder was running on AC (which it normally is, although I have a battery fully charged and installed as backup in case of premises power loss). And I learned where in the settings I could disable the various status messages, always displayed on the camcorder’s integrated LCD, from also being visible over the HDMI tether.
I fired up the camcorder and joined a Zoom meeting; at first, everything was great. Others in attendance commented on how much better the video images of me looked, and by moving the Zoom application windows from the laptop’s integrated LCD to the external display I got the camcorder’s perspective of view dialed in. Things went downhill, however, the first time I went off mute and started to speak; others quickly pointed out that my video was lagging my audio by a notable amount (i.e., I had broken “lip sync”, with the audio now in the lead).
I speedily determined, with the benefit of past experience as a guide, what was going on. I was using a microphone direct-connected to the computer for audio, but the conversion processing of the Cam Link 4K was introducing not-insignificant delay on the video prior to its computer ingest. Voila: lip sync loss. The prior experience I’d recalled was with one of the presenters at the Embedded Vision Summit earlier in the year, who had a similar setup. He was using Open Broadcaster Software (OBS) as his recording platform, which as it turns out supports user-adjustable audio delay for exactly such sync-fixing scenarios. But Zoom, which presumes the use of integrated (or alternatively USB direct-tethered) webcams, isn’t as sophisticated.
The easy fix for that particular meeting was to switch to the camcorder’s integrated stereo electret condenser microphone set; since both the audio and video were now coming from the same source and getting delayed by the same Cam Link 4K adapter, sync was restored. But this wasn’t an optimal long-term approach. As with any external mic, to a varying degree depending on coverage pattern and sensitivity, the camcorder’s built-in mic set can discern and pass along to the audience not only your voice but also any ambient noise. And speaking of “your voice”, given the camcorder’s ~2.5’ distance from me, my normally soft voice wasn’t going to get picked up very well, nor was my constantly yelling at it going to work (for me, not to mention my wife, the dogs, the neighbors…).
Next step: an external microphone connected to the camcorder, which thankfully provides a 3.5mm (1/8”) audio input jack for such purposes. One upfront qualifier; the VIXIA HV30 requires that the mic be self-powered, not phantom-powered through the audio connection, which rules out most of the smartphone-intended passive lavalier mics you’ll find from a search of Amazon’s website or elsewhere. Fortunately, speaking of Amazon, I’d bought a no-name self-powered lav earlier in the year on sale (and, it now seems, closeout) for $11.60:
Its 8m (26+ feet) total cable length was more than adequate, but as you can see from the above photos, it’s a dual-capsule setup intended for interviews. There’s no way that I can tell to mute one of the two capsules, and although I can clip them both to the front of my shirt, the result is a bit cumbersome (not to mention virtually impossible to visually hide from others’ view).
Then I remembered the Marantz PDM-750 wireless lav set (transmitter-plus-receiver-plus-omni mic) I’d bought on sale (and also, it now seems, closeout) in late 2020:
To this day, I can’t figure out why this set is seemingly no longer available for sale new from anyone save for (heavily discounted, to boot) the eBay retailer I got mine from. It’s dual-channel 2.4 GHz ISM-based, versus piggybacking on (hopefully) unused TV channels or leveraging other “lesser” RF spectrum and approaches. And it works great: don’t take my word for it; check out this expert’s review:
I suspect that as a comparatively late entrant to the market, Marantz wasn’t able to carve out a sufficiently sizeable share quickly enough to satisfy its fiscal needs, and bailed (COVID’s effective ban on face-to-face recording sessions didn’t help, of course). For those of you who’ve already perused my recent “2022 Look Ahead” piece, by the way, this mic set is precisely what pushed me over the edge into finally, fully embracing rechargeable AA batteries. And the VIXIA HV30 also conveniently includes a “cold shoe” atop it (like the analog mic input, not always an available option) which works well as a mounting point for the wireless mic receiver.
Here’s what the entire setup looks like from the front of my laptop; as you can see if you look closely, I’m also AC-powering the wireless mic receiver via its micro-USB power input and a separate DC “wall wart” (again with AA batteries as the backup power source):
Yes, your eyes don’t deceive you: on-screen is the in-process Word draft of this very write-up, which I was working on as I snapped the photo! Also note the recently mentioned dual-LED light set peeking out of both upper corners of the image.
In general, things work smoothly and reliably (if I keep a close eye on the wireless mic transmitter battery levels, that is!). That said, other meeting attendees occasionally mention brief audio dropouts, accompanied by video “jagginess” indicative of interlaced field corruption. Both derive from the same tandem source, I suspect:
Payload first. Keep in mind that unlike with a traditional webcam that is—intentionally, I suspect, and not just for cost reasons—comparatively low in resolution, and often outputs low bitrate lossy compressed video (Motion JPEG, H.264, etc.) the 1920×1080 pixel HD video coming out of the VIXIA HV30 over HDMI is uncompressed and high bitrate: ~1.5 Gbps for the video alone, not counting audio, etc., if my math is correct!
That’s a lot of data to be USB3-converted and -output (again, uncompressed) and passed to (and through) the system. Other subsystems also tapping into that same USB3 system bus can interfere with (and be interfered with by) the Cam Link 4K-sourced audio and video data, which has stringent latency requirements in order to avoid the types of artifacts I’ve described. And even if the Cam Link 4K-sourced data stream reliably makes it to the system processor(s), it still needs to be dealt with there in a robust matter. As I mentioned in my earlier write-up, the CPU and GPU in this particular laptop are sufficiently “old school” that Zoom’s more advanced virtual background effects aren’t even supported by them, for example. Extrapolating, I suspect a more modern system will do a better job with this Cam Link 4K-based setup, so while I may mothball it for the time being, I certainly won’t get rid of it.
There’s my setup for, if not now, the near future. Passing through 2,000 words, I’ll close for now, with an as-usual invitation to share your thoughts in the comments!
P.S. For anyone interested in hacking the VIXIA HV-30 firmware (although switching the HDMI output to something other than 1080i60 doesn’t seem possible, sorry), here are some resources I came across while doing my feasibility research:
This article was originally published on EDN.
Brian Dipert is Editor-in-Chief of the Edge AI and Vision Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the company’s online newsletter.