Version: 1.18
PRELIMINARY/CONFIDENTIAL
TrueSpeech® Co-Processor
9.7.2
Recording Modes
RECMODE
Frame Size
(Words)
Recording Modes
000
48-4
Compressed Speech: TrueSpeech (8.5, G.723.1 6.3/5.3, 4.8 and 4.1) etc.
See: Select TrueSpeech/G.723.1 Record Rate
001
010
011
100
101
110
111
Reserved
Reserved
Reserved
120
240
120
120
64 Kbits/sec A-law/µ-law PCM (120 words per 30ms data frame)
128 Bit/sec 16-bit linear (240 words per 30ms data frame)
64 Kbits/sec 8-bit signed linear (120 words per 30ms data frame)
64 Kbits/sec WSS 8-bit unsigned linear (120 words per 30ms data frame)
Notes:
All data rates assume that the CODEC connected to the CT8022 operates at 8000 samples/sec
The 30ms frame interval is based on counting 240 samples from the CODEC. Refer to the section on
setting the base frame size
Mode 100, PCM A-law/µ-law is a pass- through mode, where the data from the CODEC is passed to
the Host entirely unmodified, (if the record volume is set to 0100H).
16 bit linear data is signed integer (2’s complement form), positive full scale is 7FFFH, negative full
scale is 8000H, zero is 0000H
8 bit linear data is signed byte (2’s complement form), positive full scale is 7FH, negative full scale is
80H, zero is 00H
8-bit linear WSS data is unsigned byte, positive full scale is FFH, negative full scale is 00H, and 0 is
80H. This is the format used for 8-bit WAVE format data (Microsoft Windows Sound System). Data
can be converted between the two 8-bit signed/unsigned formats by simply inverting them.
The compressed speech rate for TrueSpeech 8.5,6.3/5.3 (G.723.1), 4.8 or 4.1 KBPS etc. is selected
using the Select TrueSpeech Rate command
Selection between A-law/µ-law is made using the CODEC configuration command. With an external
µ-law CODEC configured, RECMODE = 100 selects µ-law data. With an external A-law CODEC
configured, RECMODE = 100 selects A-law data.
The RECMODE and PLAYMODE bit assignments are different. See Playback command
(Section 9.8)
CT8022A11AQC FW Revision 0118 DSP GROUP, INC., 3120 SCOTT BOULEVARD
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
59
All specifications are subject to change without prior notice.
ETC [ ETC ]
