brian on 2008.04.09
at 11:35 pm
I’ve done a lot of live audio and video broadcasts on the web. I produce our virtual seminars (some people call them “webinars”) at work, and I’ve done a good deal of audio/video chats through both iChat AV and Skype. Here’s some tips and voodoo I’ve learned from that experience that should help the quality of your live, online audio and video.
Bandwidth is king. You must do all you can to save the bits, like they were water in the desert. When bits are lost, you get disruptions in your call. Here’s how to best preserve them. First, if at all possible, a wireline to your Internet connection is strongly preferable to a wireless (WiFi) one. (note: many WiFi routers have ethernet ports on the back that you can plug into!) Sometimes you need to turn off your computer’s WiFi connection altogether to get the best performance over the wire.
Sometimes you’ll have an amazing connection on wireless, but the problem with it is that it is highly variable. Your bandwidth has a strong correlation to the atmospheric conditions, things that are outside of your control, like your neighbors networks (and what channels they’re on, and those channel’s proximity to yours), and the weather. And then there are tons of things that are within your control, but may take you a long time to control for. Somethings that are controllable in a perfect world, you may not be able to, like who else is using your network, what they’re up to. Again, if you can plug into your router, do it.
This is already going to be a long post, so let’s go into some additional detail. Let’s say you have to use a wireless connection; here’s how to maximize it. First, get as close to the router as possible. Speeds drop off dramatically, starting at 10 feet. Second, if you can have “line-of-sight” with the router (no physical obstacles in between you), this is best. Then, find out what kind of wireless radio (card) you have in your computer, and what kind is in your wireless router. There are four kinds of WiFi. 802.11A/B/G/N. Many routers and cards can speak several, if not all of these. Your best connection is one where where your card’s fastest mode is the same as the only mode the router.
The most common flavor of WiFi is “B,” and it is the slowest. Nearly all routers have at least B, and often bundle B with one or more of the other flavors. If you have a only-B card in your machine, you can skip ahead to the next paragraph. Switching your router to only B-mode will yield at best only mild improvement. For you proximity and making sure as few people are using the router concurrently are the biggest factors.
Nearly as many cards out there today (if not more at this point) can speak both B&G. If you have this kind of card, and you have administration over your router, switch the router to G-only. This will bolster your throughput greatly, but at the cost of reducing the number of devices that can connect to the router. If others are using your router, you may be denying them access. If everyone who uses your router can talk G, by all means, switch and stay that way! I have recently been able to do this (just updating the one device on my network that could only understand B, and low-quality encryption) and my network is notably more stable. I suspect a huge number of people have B/G cards and B/G routers, and are running in B/G hybrid mode. These people could gain a lot by switching off the B. The hybrid mode theoretically wasn’t supposed to slow the network, but in practice, this is not the case.
If you have A, you are in a slim minority. Again, choosing to run one matched 802.11 network is best. If you have N capabilities (only in very new stuff, because the N-spec [as of this writing] has not yet been ratified Your stuff conforms to a draft of the N-spec! If you have N-capable card and router, and you switch your router to N-only (you’re very likely to be closing something off your network, if you have multiple devices) doing this should give you near-wire dependency (it’s still fallible radio waves though! Just higher bandwidth and somewhat more reliable waves!)
OK, enough about your connection. What else?
You also conserve bandwidth, by not stealing it from yourself. There are so many apps nowadays on our computers that are constantly pinging the Internet for things large and small. Eventually, your other IM apps, your 7 email accounts, your GMail and GCalendar checker, your weather widgets, your dashboard widgets, or Vista gadgets, your OS software updates, your plugin updaters, your major software updaters, your iTunes, your photo app, your web app open in another browser, your BitTorrents, Miro/video apps, your background sync-to-web and backup apps, you shared connections to other computers on your intranet, to your file server, your background VNC server, your own computer’s file sharing, FTP, web sharing, and the new Adobe AIR hybrid app you just downloaded… are you starting to get the picture? These bandwidth leeches are everywhere! A thousand needle pricks and pretty soon you’ve bled to death.
Turn off as many of these as possible! If you’re on a Mac, here’s an easy tip: log out. Then log back in, and as soon as you type your password, hit enter, and immediately hold the SHIFT key. This tells your computer to not launch any applications when you log in. Then, only open the applications you must use during the call. There’s probably a way of doing this for Windows, but I’m not the guy to tell you how! (What do I know?)
Now we’re going to audio fidelity on your local equipment. First, find the quietest space you can. All mics work better when there are fewer competing soundwaves around to capture! Second, be as close to your mic as possible, but not closer. By this I mean, there’s a sweet spot. If you’re too close, you’ll have to be careful not to over power the mic with your voice. Secondly, you need to be sure to not speak directly into the mic, but at a slight angle. This will help to avoid “plosives.” Those are the sound pops when you say certain consonants like “P” and “B.” Those listening will be thankful. If you have a meter to watch while you talk, it probably goes from left to right, and at the far right the colors probably change, like from green on the left, to yellow/orange to red. The louder you are, the more right the lights go. The goal is to get as much green as possible, rarely touch the orange, and never touch the red. Red = distortion.
So talk closely, at a slight angle and adjust your loudness and your proximaty to the mic to get as much green as possible. It takes just a little progress, but makes a ton of difference.
The nicest mic you can afford will notably improve your sound. You can get a quality headset mic for around $40-50. However, there are some iffy ones in that price range. They get pretty reliable at $60 and up. Headsets have the advantage of keeping the mic at a constant distance from your mouth, so you never have to think about moving.
Really nice, stand-alone podcasting mics with USB connections around $100 will give you pretty much as much quality as you can transmit through a PC without things like a mixing board. Blue and Samson make excellent stand-alone USB mics in this price range. However, most people will just buy a headset mic marketed as a “Skype-certified,” and most will be very happy with them.
Many laptops have built in mics. They vary in quality from awful to pretty decent. You might have guessed, all the latest Macs (hold Mac mini and Mac Pros) have pretty good built in mics, so long as you’re in a pretty quiet area and are fairly close. However, headsets or stand alone mics above the $50 range are going to be better.
Listening to the audio of your comrades is best accomplished with some form of headphones. If you’re using a headset mic, you’re done. Skip this section. If you’re using stand alone mic, you’ll want to use headphones to hear incoming audio. If you use speakers and any mic, you’ll easily get feedback and echoes and all sorts of audio gremlins. As Lolcats would tell you, “Do not want.” One side note: Macs with iChat AV can use their built in-mics and built-in speakers in concert because they use some echo/feedback suppression algorithms. Pretty cool.
I’ve gone on long enough. I’ll leave you with one less phenomenon. You connection will get better as you continue to talk. This works in two ways. First, during the first minutes of the conference, the network you’re chatting on is trying to optimize the connection between all the parties. Once it does this, usually under 5-10 minutes, you’ll notice. Secondly, if you haven’t been talking into your mic for, say 30 seconds or more, the noise cancellation in most conference software is suppressing background noise, so when you start talking, your listeners may loose your first syllable to this. I’ve found this to be especially bad on Adobe’s Acrobat Connect software (what I’ve found otherwise to be the best “webinar” software around by a margin). So be aware. However, if you start most of your sentences with “Ummmm…” or “Uhhhh…” you’ll be all set. :-)
Go forth and have good A/V chats with the world!
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