Broadcast Tools SS 4.1 III Instrukcja Użytkownika Pobierz pdf (Strona 17)

1.1.3 Services

Every facility at which Rivendell is deployed is presumed to have one or more ultimate

destinations for which audio is intended. These could be radio stations (e.g. WAVA),

satellite uplink channels, live Internet audio streams, or any mix of the above. Each of

these sorts of destinations is referred to in Rivendell as a service, and certain parameters,

particularly as regards audio play out and log (playlist) creation, can be configured on the

basis of what particular service is being referenced.

Section 1.2 The Rivendell Hardware Paradigm

In addition to the core computer hardware (CPU, motherboard, etc), each Rivendell host

typically interacts with specialized hardware required to accomplish the task at hand.

Three main categories of such 'special' hardware are of interest to us here, the three being

audio adapters, serial ports and GPIO/switcher devices. We'll cover each below.

1.2.0 Audio Adapters

An audio adapter in Rivendell is simply a device or facility for getting audio into and/or

out of a host on a realtime basis. Most commonly this will be a sound card, although

other, more exotic possibilities (using TCP/IP networking or direct routing to other audio

applications) also exist. The three main classes of audio adapters supported by Rivendell

are:

Advanced Linux Sound Architecture (ALSA) – The standard Linux

sound card driver starting with the 2.6.x kernel series, ALSA supports a

huge array of commercially available sound cards, ranging from entry

level 'game' cards to high-end cards aimed at professional audio uses.

More information, including a current list of supported cards, is available

at the ALSA web site, http://www.alsa-project.org/.

HPI Adapters – These are high-performance sound cards manufactured

by AudioScience Corporation. Designed and built specifically for

broadcast automation applications, many feature advanced capabilities

(such as on-board MPEG codecs and AES3 i/o) specially aimed for use in

that setting. They are so-called because Rivendell uses AudioScience's

special 'HPI' driver to access and control them. More information is

available at AudioScience's web site, http://www.audioscience.com/.

JACK Audio Interconnect Kit – JACK is not a particular set of

hardware devices, but rather an audio 'framework' that allows compliant

applications to share audio resources and route audio in realtime amongst

themselves. JACK is different from similar efforts within the Linux realm

in that it was designed from the ground up for professional audio work,

with particular focus upon low-latency operation and synchronous

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Broadcast Tools SS 4.1 III Instrukcja Użytkownika Strona 17