Posted: Thu Feb 03, 2000 10:07 pm Post subject: [Asterisk] DIY Echo Cancelation
I have been tossing around building a 16 channel A/D D/A board that
plugs up to the parallel port. Add some ring detection/generation
and on/off hook sensing and I think it might suffice for a pretty
channel interface for asterisk.
The stumbling block is echo canceling. Would it be too much to ask
asterisk to do the echo canceling or is that something that really
needs to be done at the hardware level.
Posted: Fri Feb 04, 2000 4:23 pm Post subject: [Asterisk] DIY Echo Cancelation
Quote:
I have been tossing around building a 16 channel A/D D/A board that
plugs up to the parallel port. Add some ring detection/generation
and on/off hook sensing and I think it might suffice for a pretty
channel interface for asterisk.
The stumbling block is echo canceling. Would it be too much to ask
asterisk to do the echo canceling or is that something that really
needs to be done at the hardware level.
That's a good question. I recently found some echo cancelling code, but I
haven't been able to get it to work yet. Look in /pub/asterisk/devel on
ftp.asteriskpbx.com and you'll see the code. If you can get it to work at
least in principle, I'd like to see something like this:
/* Make a new echo canceller structure */
extern struct ast_echo_canceller *ast_aec_create(void)
/* Apply 'count' samples as being read into the aec */
extern int ast_aec_reader(struct ast_echo_canceller *aec, signed short
*samples, int count);
/* Echo cancel 'count' samples to be transmitted */
extern int ast_aec_writer(struct ast_echo_canceller *aec, signed short
*samples, int count);
/* Destroy the echo canceller */
extern void ast_aec_destroy(struct ast_echo_canceller *aec);
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