User`s manual

EAGLE
Multi-Standard Dual-Channel Digital Audio Codec
4
1.3. Encoding Algorithms.
Main function of the AUDIOCODEC is to establish one or two bidirectional audio channels
between distant points for receiving a telephone chronicle, for transmitting with a high quality a
sports commentary voice or for establishing an audio link between two studios. In the remote
site, a telephone or another AUDIOCODEC will receive the encodec audio and will decode it
into audio signal.
The requirementes of the communication channel in each of these applications are different and
depends on the type of audio signal to be transmitted (voice or music, mono or stereo), required
audio bandwith, delay time, etc.
All available encoding algorithms features are compared in the following figure:
Encoding Algorithms
Transmission
rate
Audio
format
Audio
bandwith
approximate
delay time*
Available in
channels
Ancillary
datachanel
VOICE ALGORITHMS – For transmitting voice with
telephone quality.
G.711 LAW-A (EUROPE) 64Kbps Mono 3.5kHz 37 mseg L1 & L2 NO
G.711 LAW-µ (USA & JAPAN)
64Kbps Mono 3.5kHz 37 mseg L1 & L2 NO
SPECIAL ALGORITHM AUDIO+DATA
AEQ-3.5 32kb 64 (32+32) Mono 3.5kHz 25 mseg L1 & L2 YES
STANDARD ALGORITHMS – For transmitting voice with
medium quality.
G.722 STAT 64Kbps Mono 7kHz 21 mseg L1 & L2 NO
G.722 H.221 64Kbps Mono 7kHz 20 mseg L1 & L2 YES
MPEG 64 ALGORITHMS – For transmitting voice in high
quality and music in medium quality.
MPEG L2 64 24 kHz 64Kbps Mono 11kHz 450 mseg L1 & L2 YES
MPEG L2 64 32 kHz 64Kbps Mono 10.5kHz 340 mseg L1 & L2 YES
MPEG L2 64 48 kHz 64Kbps Mono 10kHz 240 mseg L1 & L2 YES
MPEG L3 64 48 kHz 64Kbps Mono 15kHz 235 mseg Only L1 NO
SPLIT 64 ALGORITHMS – To transmit and receive using
different algorithms.
MP3 SPLIT 64 cMP3 dG722 64Kbps Mono Tx 15kHz
Rx 7kHz
Tx 235mseg
Rx 21mseg
Only L1 NO
MP3 SPLIT 64 cG722 dMP3 64Kbps Mono Tx 7kHz
Rx 15kHz
Tx 21mseg
Rx 235mseg
Only L1 NO
128 MONO ALGORITHMS– For transmitting voice and
music (mono) in very high quality.
AEQ LD-2 128Kbps Mono 15kHz 22 mseg L1 + L2 NO
MPEG L2 128 MONO 48 kHz (J.52) 128Kbps Mono 20kHz 320 mseg L1 + L2 YES
MPEG L2 128 MONO 48 kHz (IMUX) 128Kbps Mono 20kHz 240 mseg L1 + L2 YES
MPEG L3 128 MONO 48kHz 128Kbps Mono 15kHz 550 mseg L1 + L2 NO
128 DUAL ALGORITHMS – For transmitting two voice
channels in very high quality.
MPEG L2 128 DUAL 32 kHz (J.52) 128Kbps Dual 10.5kHz 470 mseg L1 + L2 YES
MPEG L2 128 DUAL 32 kHz (IMUX) 128Kbps Dual 10.5kHz 345 mseg L1 + L2 YES
128 MPEG STEREO ALGORITHMS– For transmitting
music in medium and high quality.
MPEG L2 128 JOINT 48kHz (J.52) 128Kbps Stereo 15kHz 300 mseg L1 + L2 YES
MPEG L2 128 JOINT 48kHz (IMUX) 128Kbps Stereo 15kHz 240 mseg L1 + L2 YES
MPEG L3 128 STEREO 48kHz 128Kbps Stereo 15kHz 550 mseg L1 + L2 NO
256 MPEG STEREO ALGORITHMS – For transmitting
music in very high quality (Only through V35).
MPEG L2 256 STEREO 48kHz 256Kbps
Only V.35
Stereo 20kHz 110 mseg** - YES
* Delay Time measures the time that goes between audio is feed into one AUDIOCODEC input
until it reaches remote AUDIOCODEC output. It implies encoding time plus transmission time
plus decoding time. This measures had been obtained using an ISDN switchboard that has very
low transmission delay. So real time in a long distance communication will be higher than this.
Ancilliary Data channel usage does not affect delay time.
In the following page, the different encoding algorithms are explained.