Version: 1.18
PRELIMINARY/CONFIDENTIAL
TrueSpeech® Co-Processor
9.22.2
Host-to-Host Decompression
Host-to-Host decompression from the viewpoint of the Host is similar to the playback process. The protocol used to
transfer compressed data frames from the Host to the CT8022 [3] is the same as that used for playback in DATA
sync mode. However, instead of using the playback C1 command to start the process, the Host-to-Host
decompression C1 command is used. Note that in the case of decompression, the Host must still send the playback
C2 and C3 commands after sending the decompression C1 command to start the decompression process. The
decompression C1 command replaces the playback C1 command, but the playback C2 and C3 commands are still
required when starting decompression. The decompression C1 command is also used to transfer the actual
uncompressed data frames from the CT8022 [1].
The following command is used to start Host-to-Host decompression:
Decompress Command C1:
1111 11
(15-10)
PLAYMODE
(9-7)
000 0
(6-3)
TFR_MODE
(2-1)
0
(0)
Status Response S1:
1111 11
PLAYMODE
(9-7)
000 0
(6-3)
TFR_MODE
(2-1)
READY
(0)
(15-10)
When starting decompression, this command must then be followed immediately by the playback C2 and C3
commands. Note that when the first decompression C1 command is sent to start decompression, the READY flag in
the status response will not be set, since at this point the CT8022 will have no decompressed data available.
To Start Playback:
Playback C1
To Start Decompression:
Decompress C1
Playback C2
Playback C3
Playback C2
Playback C3
9.22.2.1
Playback (Decompression) Modes
PLAYMODE
Playback Modes
000
001
010
011
100
101
110
111
TrueSpeech at 8.5, 6.3, 5.3, 4.8, 4.1 Kbits/sec
Reserved
64 Bit/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
Refer to Section 9.8 for more details on PLAYMODE and TFR_MODE.
CT8022A11AQC FW Revision 0118 DSP GROUP, INC., 3120 SCOTT BOULEVARD
SANTA CLARA, CA 95054 PH: 408 986 – 4300 FAX: 408 986 – 4490
149
All specifications are subject to change without prior notice.
ETC [ ETC ]
