[Asterisk-Users] Re: ztdummy/rtc - staticy audio

[Rob Thomas]

> output of zttest:
> Opened pseudo zap interface, measuring accuracy...
> 99.938965% 99.951172% 99.938965% 99.963379% 99.963379% 99.951172%
> 99.951172%

Ah. Don't be scared. This is actually -correct- when using RTC. Let me
demonstrate:

[root at dhcp5 zaptel]# ./zttest -v
Opened pseudo zap interface, measuring accuracy...

8192 samples in 8195 sample intervals 99.963379%
8192 samples in 8195 sample intervals 99.963379%
8192 samples in 8187 sample intervals 99.938965%
8192 samples in 8195 sample intervals 99.963379%
8192 samples in 8187 sample intervals 99.938965%
8192 samples in 8195 sample intervals 99.963379%
8192 samples in 8187 sample intervals 99.938965%
8192 samples in 8195 sample intervals 99.963379%
--- Results after 8 passes ---
Best: 99.963379 -- Worst: 99.938965 -- Average: 99.952916

Note how it's bouncing below _and_ above 8192?  That's the important
bit. With RTC it can do the equivalent of 'catching up'. (Not really, I
know, but lets pretend it works that way) Now lets see what happens when
we average it out:
[root at dhcp5 zaptel]# bc
bc 1.06
Copyright 1991-1994, 1997, 1998, 2000 Free Software Foundation, Inc.
This is free software with ABSOLUTELY NO WARRANTY.
For details type `warranty'.
(8195+8195+8187+8195+8187+8195+8187+8195)/8
8192

Exactly 100% spot on, and it should stay that way indefinitely. Note, of
course, that timing is only used for Meetme, MOH and IAX Trunking. So
this isn't your problem - although you did say that MOH was working
perfectly, so you can at least take comfort in that!

--Rob