IP-based Audio Distribution
Save money by keeping an eye on this changing market
By now it's pretty well understood that the growth and excitement for moving “broadcast-able” audio from point-to-point (POTS, ISDN, etc.) centers around IP transmission. It's a good time to take a look at the state of this technology and where it's headed.
Here in the wired world
Good IP codecs now have ultra-low delay coding like AAC-ELD and dynamic buffer managers, so when utilizing an Ethernet connection on a reasonable-bandwidth IP link, these now rival the reliability and delay factors previously experienced with ISDN. This is good because many users are reporting reluctance of telcos to continue to provide and support ISDN, especially for short-term use. And IP of some flavor is now universally easier to obtain than a POTS connection (especially one guaranteed to support a POTS codec). The main pitfalls with wired IP concern fire-walling, dynamic IPs and breaking through commercial login screens.
If you're connecting an IP codec to a heavily secured network (like at a corporation) there are likely to be ports and protocols blocked. While you can experiment with varying port settings and protocols on your codec, it's usually safer to work with the IT department to achieve some kind of demilitarization of the connection to your codec.
Commercially available IP connections
Most publicly available IP connections rely on assigning dynamic or varying IP addresses to computers connected to them. This can complicate incoming connections to codecs. The simplest way around this problem is to be sure the studio IP codec is plainly visible from the Internet (by means of a public, static IP address), and all connections are initiated from the field. In environments where this is not practical, better codecs have a Traversal Server function, which provides some network intelligence in helping make these connections. A Traversal Server subscription (provided by the codec vendor) has the added benefit of providing a dynamic directory of all affiliated codecs that appears on the codec itself much like a buddy list. This way, the user is completely removed from having to know anything about IP addresses on either end of the link, removing the dynamic IP problem as well.
If you've ever connected to the Internet at an airport, hotel or coffee shop, you know that they always redirect new users to a login page, regardless of whether the access is free or paid. Many IP codecs connected directly to this type of link have no way of allowing the user to click through this login page. It's possible to utilize a laptop ahead of the codec to spoof the system into thinking it's a laptop connection, and using the laptop browser to do the login. But this arrangement is burdensome and complex, so it makes more sense to have a portable IP codec with an integrated browser for these locations. Of course, a codec that easily talks Wi-fi will help here as well.
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