Podcast Recording Shootout
The two main contenders that are suitable for workhorse podcast use are Skype and Gizmo. Both are very easy to download and install. Both offer comparable rates on calls coming in from the phone network and going out again, both nationally and internationally (though Gizmo has a slight edge in this respect). Both are user-friendly and easy to get potential guests set up on so they can be on your show.
They both are usable. They both are workable. They both run quite well on Linux, Windows and Mac OS. Their feature sets are comparable in many respects. But, they are not the same.
Neither Skype nor Gizmo offers anything in the way of 64-bit versions for Linux, even though there are user complaints and pleadings about this dating back to May 2005 on both companies' support forums on exactly this topic. Skype recently has introduced a 64-bit Vista client, but Mac and Linux 64-bit clients are, as yet, nothing more than a pleasant adolescent fantasy for the lonely off-platform user. Gizmo, meanwhile, is 32-bits all through.
Both install and run on 64-bit distros, with a little bit of a headache making sure they've got the right 32-bit libs to call in and with setting up the chroot environment. It's a stopgap that works okay, but it ain't pretty, and in a time when 32-bit desktop and laptop processors are being end-of-lifed by hardware manufacturers, this situation really is irritating.
Skype, now the prized stepchild of the eBay corporation, runs on a proprietary peer-to-peer networking back end that co-opts the user's system resources to route calls, up to the maximum of what it can grab that's not being used by other systems. This is comparable to how BitTorrent works, though unlike with BitTorrent, users have no control over how much in the way of bandwidth or system resources they want to allocate to the task. The practical upshot for this where performance is concerned is curiously double-edged. At the beginning of a Skype call, the connection typically is loud and clear, the mix is well proportioned, and the compression artifacts are very difficult to hear (and, if you're good with EQs, you can pretty much notch out the most obvious ones). However, as a call progresses, more of your personal bandwidth gets allocated to other network calls, and the quality of the audio gradually degrades. At low traffic times, this effect is barely noticeable, but at high traffic times, you may find yourself having to restart the call every 10–15 minutes as the quality falls below what you find acceptable (or intelligible).
Its networking setup isn't the only thing that's proprietary—it's also a closed system. Skype's network can't be dialed in to directly from any other voice-conferencing network. The standards are closed, and they're black-boxed. Although this isn't a problem that's directly relevant to podcasting, if you're looking for a general first-line VoIP package, it's something you'll want to keep in mind. Skype is like Vegas: what happens there, stays there—well, assuming its encryption algorithms are robust.
Gizmo, a service and application owned by SIPphone, Inc., has a somewhat different approach. Although the software itself is proprietary, it uses the open SIP protocol for its transport across the Net, and calls are routed directly over the SIPphone network between the individual call participants, rather than being routed through a peer-to-peer network. Because it uses SIP and Jabber, it can hook up with any software using either of these protocols fairly transparently.
Gizmo uses TLS and SSL encryption to discourage eavesdropping—open technologies whose strengths and limitations are well known. The corporate culture is deliberately geared toward transparency rather than toward opacity, which is an operating philosophy that warms the cockles of this Linux geek's heart. However, when it comes to encryption, Gizmo also loses a point, as it does not encrypt between Gizmo and non-Gizmo SIP clients.
The sound quality on Gizmo follows a different curve from Skype. Because Gizmo routes over the SIP network instead of through a peer-to-peer setup, it is more subject to the fickle winds of fate. When Net traffic is up, Gizmo calls tend to decay. When it's down, they do better. However, Gizmo does not progressively degrade performance over the course of a call or take your bandwidth for allocating to other calls on the network.
In terms of actual performance, the sound quality is usually a wash, but Gizmo consistently sounded better the times I've used it for multiparty conferences than has Skype, particularly on extra long calls.
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