TrueSpeech® Co-Processor
PRELIMINARY/CONFIDENTIAL
Version: 1.18
If the speech frame is 240 and the AEC adaptation limit is set to 120, the peak adaptation processing load is reduced
by 50% and the AEC adaptation (training) time is doubled. If the limit is set to 60, then the load is reduced by 25%,
and the adaptation (training) time is quadrupled.
The following command sequences can be used to program the AEC adaptation limits:
To set the maximum AEC adaptation limit:
C1
S1
C2
S2
E02CH
E02CH
00XXH
00XXH
Where XX is the adaptation limit
To set the minimum AEC adaptation limit:
C1
S1
C2
S2
E02DH
E02DH
00XXH
00XXH
Where XX is the adaptation limit
9.15.3.1
Reading the CT8022 DSP Processor Load
The Host can check if the CT8022 DSP Processor is being over-committed by polling the DSP processor load for the
current speech frame.
Command:
Status
511BH
load-value
When the load value returned is 0, the DSP processor is 100% loaded.
The load value is measured by counting the number of internal CODEC interrupts that the DSP receives when it is an
internal idle loop waiting for availability of the next speech frame to process. When this value reaches zero, it
indicates that as soon as the DSP code reaches the idle loop, it finds that the next speech frame is immediately
available for processing.
The maximum value read (lowest amount of load) depends upon the speech frame size and the 8/16-bit CODEC
configuration. In 8-bit mode, the CODEC generates a single interrupt for every two 8-bit CODEC samples. With an
8.0 KHz CODEC fsync rate, a CODEC interrupt is generated every 250 µs. In 16-bit mode, the CODEC interrupt is
generated for each sample, once every 125 µs.
In 8-bit CODEC mode, with a 30ms speech frame, there will be 120 CODEC interrupts per speech frame, so that the
DSP processor load can be calculated as:
(1 - load-value/120) * 100%
In 16-bit mode with a 10ms speech frame, there will be 80 CODEC interrupts per speech frame, so that the DSP load
is:
(1 - load-value/80) * 100%
In both cases, a load value of zero indicates the DSP processor is 100% loaded. At this load level, the DSP may start
to drop speech frames.
The load level is only meaningful in Host-to-CODEC mode. It is not valid in Host-to-Host mode.
104
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 ]
