RoadRunner
U S E R S G U I D E
5
RoadRunner
. MUSICAM can deliver full duplex, 10.5 kHz monaural
audio on one ISDN ‘B’ channel. When using 112 or 128 kb/s,
transparent 20 kHz monaural audio is possible. Although a narrower
bandwidth at 56 and 64 kb/s than MPEG Layer III, audible advantages
are higher transparency, lower delay, less noticeable artifacts and better
results when cascading. At 112 and 128 kb/s, MUSICAM offers
transparent monaural audio and better cascading than either standard
ISO/MPEG Layer II or Layer III.
G.722
G.722 is one of the earliest audio coding algorithms to be standardized.
G.722 is a relatively simple algorithm based on ADPCM (Adaptive
Predictive Pulse Code Modulation) offering full duplex, 7.5 kHz audio
over a single ‘B’ channel. The essential advantages of G.722 are its
compatibility with most other codecs and very low delay times. The
main disadvantages are its limited audio fidelity, poor signal-to-noise
ratio and poor cascading.
Broadcast Capabilities
The
RoadRunner
can be configured to send the same audio program to
two different locations simultaneously. In addition, the
RoadRunner
’s
decoder can receive the return audio from both locations, and you can
easily switch to monitor the return audio from either location.
You can use any supported algorithm, and can even use different
algorithms for the send and return audio. For example, a typical
application involves sending high quality Layer III audio to the studio
from the remote location, but low delay G.722 can be used for the return
audio.
Ancillary Data
A bi-directional RS232 data path is provided for end-to-end ancillary data
communications when using any MPEG algorithm. Baud rates up to
38,400 are supported.
