TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
9.8.2
Playback Modes
PLAYMODE
Frame Size
(words)
Playback Modes
000
16-8
Compressed Speech: TrueSpeech (8.5, G.723.1 6.3/5.3, 4.8 and 4.1) etc.
Refer to Section 9.8.5 (Select TrueSpeech Playback Rate).
001
010
011
100
101
110
111
Reserved
120
64 Kbits/sec A-law/µ-law PCM (120 words per 30ms data frame)
Reserved
64 Kbits/sec 8-bit signed linear (120 words per 30ms data frame)
64 Kbits/sec 8-bit unsigned linear (120 words per 30ms data frame)
128 Kbits/sec 16-bit signed linear (240 words per 30ms data frame)
Reserved
120
120
240
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 command
for setting base frame size.
Mode 010, PCM µ-law is a pass-through mode, where the data from the Host is passed to the CODEC
entirely unmodified, (if the playback 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 zero
is 80H. This is the format used for 8-bit WAVE format data (Windows Sound System). Data can be
converted between the two 8-bit formats by simply inverting the most significant bit.
The TrueSpeech rate 8.5,6.3,5.3,4.8 or 4.1 etc. is selected using the Select TrueSpeech Playback 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.
72
DSP GROUP, INC., 3120 SCOTT BOULEVARD CT8022A11AQC FW Revision 0118
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
All specifications are subject to change without prior notice.
ETC [ ETC ]
