Digium, Inc.
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Chapter 3: Configuration
or
echocancel = 256 (this sets 256 taps or 32ms)
Users of Digium's HPEC software have the following additional options:
echocancel = 512 (this sets 512 taps or 64ms)
or
echocancel = 1024 (this sets 1024 taps or 128ms)
Please note that HPEC consumes extremely high amounts of CPU MIPS
that increase as the number of taps are increased. Audio quality issues
may result from choosing a taps length greater than the server's ability to
process the echo in real-time. If audio quality is affected, reduce the taps
length or combine your TE200 Series card with Digium's VPMOCT64.
Users of Digium's VPMOCT64 hardware echo cancellation module will
have 128ms of echo cancellation performed at all times unless explicitly
disabled by setting the echocancel variable equal to "no."