In my experience, several seconds of delay becomes apparent over time when using an internal clock source. Seems its a clocking/timer issue. Certainly we are dealing with clocking differences over time and unsynced samples are being significantly buffered and then replayed later. What are you using as a clock source? I think that basically we are looking at 50 packets/sec at 20ms each packet for alaw/ulaw voip. That is - 1 second of speech. Now, zaptel seems to time from whatever hardware clock is available and almost assumes that the clock will be precisely 8000 samples per second or 1000 interrupts/second (also 1 second of speech). It seems that the voip clock is slightly faster than the hardware clock that zaptel is timing from. The extra samples/second must be being buffered. Of course, this buffering would add up over time until the point that a VOIP sample is played back several seconds out of phase. Seems that either the zaptel clock source must be brought to closer tolerance, or the extra data that is being buffered must be thrown away in order to stay in sync. Any thoughts?
-----Original Message----- From: Tony Mountifield Sent: Sun, June 26, 2005 5:35 pm In article <[EMAIL PROTECTED]>, Dan Morin <[EMAIL PROTECTED]> wrote: > Make sure that if you're using anything other than zaptel hardware, it > is running uLaw as the codec. Anything else will produce ever > increasing delays. Hey, now that's a snippet of information I hadn't seen before! All my work with SIP and MeetMe is using aLaw, since I'm in the UK. Do you know why it causes ever increasing delays? I would have thought that a transcoding would just introduce a contstant (small) delay, not an accumulating one. So if you're right, then it ought to be fixable, once the mechanism is understood. Cheers Tony -- Tony Mountifield Work: [EMAIL PROTECTED] - http://www.softins.co.uk Play: [EMAIL PROTECTED] - http://tony.mountifield.org _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
