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One string means one vibration, or sine wave.
A single mono audio channel. |
What's the difference between HYBRIDS, CODECS, and STREAM ENCODERS?
Hybrid
In the broadcast world, a
Telephone Hybrid is needed in place of a telephone handset to connect a a caller to AIR. The phone mixes or duplexes both incoming and outgoing audio together so that the phone company only needs to transport a single audio channel.
As broadcasters, we would like to have two audio channels on the hybrid: in and out, just like a phone has a mic and an earpiece. Discrete audio is preferred so that the audio is mixed in the console instead of the phone line.
Mr. Steve Church, founder of
the company which employs yours truly, was the first person to figure out how do do this with digital signal processing instead of analog circuitry.
Cool!
The phone companies caught onto the idea of using digital transmission instead of analog and (
mostly) standardized digital signal over the same copper telephone wires with
ISDN technology back in the '80s. Since there are a gazillion phones in the world, an ISDN phone circuits can be connected to regular telephone lines, and the phone company handles the switching, a caller can call from their telephone to a radio station's hybrid and be heard "on the air," clean and without echo. This is done with the same copper phone lines as always used for Plain Old Telephone System [
POTS] phones.
Here is a comparison of the various
Telos-brand hybrids used for communicating with callers via
POTS, ISDN, and even
SIP circuits as well as the features of each.
Codec
An audio codec in broadcast is a device or used to connect remote audio to the broadcast when a device can be specified at each end of the connection. Since both ends of the connection are on common devices, it it's possible to specify the audio codec used. The Zephyr, Telos' first codec, was the first device to use .MP3 audio encoding to deliver superior sounding audio over the same ISDN lines. Codecs sounded much superior to what could be achieved with a hybrid.
The voice tracking community uses codecs frequently and extensively to be able to transmit high quality audio real-time over great distances. In the broadcast world, a connection of this type is often referred to "zephyring" in honor of Mr. Churches first codec, the Zephyr.
Now, Telos offers codecs for both ISDN and Internet-IP connections. The
Zephyr Xstream is the current incarnation of the classic Zephyr, AND still compatible all around. The classy Z/IP One is a modern
19" 1U Internet codec which is even capable of making high quality connections over 3G wireless connections.
Stream Encoders
An audio encoder in the broadcast realm typically refers to a stream encoder. Quite simply, the stream encoder makes a digital "stream" source which can be relayed to end listeners via the Internet as an alternative to traditional terrestrial radio signals. When one clicks on a "listen" link at a station's website or listens to Pandora, the data flows continuously from the stream encoder to the listening device, and there are all manners of ways of doing this.
Telos has a hardware encoder called "
ProSTREAM" and
Omnia has a software encoder called "
A/XE." The approach of each of these tools is:
- Receive stereo input audio as analog or Livewire
- Process the audio both for best listening and for proper encoding
- Encode with authentic Franhaufer codecs
- Embed the station and current play metadata
- Deliver the audio to a public streaming server for replication and delivery
Live audio is alive and well in the Internet age, thank you very much!
