[Asterisk-Users] isdn dtmf mis-detection

Adam Goryachev mailinglists at websitemanagers.com.au
Mon Mar 24 03:09:40 MST 2003


Well, since the overwhelming silence as to the location of the oft mentioned
patches to the Linux kernel and asterisk to move the isdn dtmf detection
from the kernel to asterisk itself I had yet another search using google for
these items. I still haven't found them, but I think I have managed to
create my own patch to disable the linux kernel side of the dtmf detection.
Don't ask me if I have broken anything else etc, but it looks right to me,
and I have been able to make an outbound call through the isdn card with my
patched kernel. (of course, anyone who dials into the * box won't be able to
have dtmf recognised as there is *NO* dtmf detection anywhere at the
moment).

Basically all I did is comment out a few lines as can be seen from this
snippet of drivers/isdn/isdn_audio.c
                        else
                                s->buf[s->idx++] =
                                    isdn_audio_ulaw_to_s16[*buf++] >> (15 -
AMP_BITS);
                }
/*              if (s->idx == DTMF_NPOINTS) {
                        isdn_audio_goertzel(s->buf, info);
                        s->idx = 0;
                }
*/              len -= c;
        }
}

silence_state *
isdn_audio_silence_init(silence_state * s)
{
        if (!s)

This is a small section from kernel version 2.4.21-pre5 (pre4 apparently had
some improvements, but they didn't seem to help for me, well, they seem to
be improved but still too problematic (too many complaints) to be usable.

If anyone who knows more than me thinks I've done something stupidly wrong,
please let me know, otherwise, I'll try this for a few days and see what
happens. (I only use the ISDN lines for outbound calls at the moment).

Regards,
Adam




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