
PSB 7238
General Architecture and Functions
Semiconductor Group
23
Data Sheet 1998-07-01
2.2.2
Audio Functions and Supplementary Features
General
The uncompressed/compressed audio is applied to the interfaces as follows:
“Transparent” means that data is received/transmitted in a time-slot without protocol.
1. Full Duplex G.728 Encoding/Decoding of One Audio Channel
Audio coding according to ITU-T G.728 fixed point recommendation using Low Delay
Code Excited Prediction (LD-CELP, 16 Kbit/s), offering toll quality audio. The postfilter
of the G.728 may be switched on (offering a higher quality impression) or off (providing
objective better S/N values).
2. Full Duplex G.723 Encoding/Decoding of One Audio Channel
Audio coding according to ITU-T G.723 recommendation using Multipulse Maximum
Likelihood Quantization (MP-MLQ, 6.3 Kbit/s) or Algebraic Code Excited Linear
Prediction (ACELP, 5.3 Kbit/s). The high pass filter, the postfilter and the Voice Activity
Detection of the G.723 may be independently switched on or off.
3. Full Duplex G.722 Encoding/Decoding of One Audio Channel
Audio coding for 7-kHz voice using the Sub-Band Coded Adaptive Differential PCM
(SB-ADPCM) algorithm according to the G.722 Recommendation.
4. Serial H.221/223 Oriented Audio Protocol
The PSB 7238 supports a serial H.221/223 oriented audio protocol for direct connection
to a Videocodec (VCP of 8
×
8 Inc.). This protocol provides an outband synchronization
of the audio bit streams by using block structures for the compressed audio data.
Uncompressed Audio
IOM-2 (transparent)
Compressed Audio
SAI (H.221/223 oriented audio protocol or
transparent)
Host IF (interrupt handshake protocol with
minimized interrupt load for the host)
Host IF (interrupt handshake protocol)
IOM-2 (transparent)
Host IF (interrupt handshake protocol)