Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 16 Dec 2002 12:47:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 16 Dec 2002 12:47:20 -0500 Received: from mailout08.sul.t-online.com ([194.25.134.20]:47256 "EHLO mailout08.sul.t-online.com") by vger.kernel.org with ESMTP id ; Mon, 16 Dec 2002 12:47:16 -0500 Reply-to: Wolfgang Fritz To: linux-kernel@vger.kernel.org From: Wolfgang Fritz Subject: [PATCH] (Was: i4l dtmf errors) Date: Mon, 16 Dec 2002 18:44:58 +0100 Organization: None Message-ID: References:

Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="nextPart1113440.8i0y9mmqF5" Content-Transfer-Encoding: 7Bit User-Agent: KNode/0.7.1 X-AntiVirus: checked by AntiVir MailGate (version: 2.0.1.7; AVE: 6.17.0.2; VDF: 6.17.0.5; host: gurke) X-AntiVirus: checked by AntiVir MailGate (version: 2.0.1.7; AVE: 6.17.0.2; VDF: 6.17.0.5; host: gurke) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6551 Lines: 192 --nextPart1113440.8i0y9mmqF5 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 8Bit Kai Germaschewski wrote: > On Sat, 14 Dec 2002, Wolfgang Fritz wrote: > >> > it seems isdn4linux detects DTMF tones from normal speach. This is >> > rather annoying when using i4l for voice with Asterisk.org. This is >> > tested on all recent kernels >> >> The DTMF detection is broken since kernel 2.0.x. I have a patch for a >> 2.2 kernel which may manually be applied 2.4 kernels with some manual >> work. It fixes an overflow problem in the goertzel algorithm (which >> does the basic tone detection) and changes the algorithm to detect >> the DTMF pairs. If interested, I can try to recover that patch. > > If you dig out that patch and submit it (to me), I'm pretty sure > there's a good chance of it going into the official kernel. ISTR there > was talk about that earlier, but nothing ever happened. > > --Kai > Here is the patch against 2.4.20. Wolfgang > > - > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ --nextPart1113440.8i0y9mmqF5 Content-Type: text/x-diff; name="dtmf.patch" Content-Transfer-Encoding: 8Bit Content-Disposition: attachment; filename="dtmf.patch" diff -urN -X dontdiff linux-2.4.20/drivers/isdn/isdn_audio.c linux-2.4.20.mod/drivers/isdn/isdn_audio.c --- linux-2.4.20/drivers/isdn/isdn_audio.c Mon Feb 25 20:37:58 2002 +++ linux-2.4.20.mod/drivers/isdn/isdn_audio.c Mon Dec 16 17:45:39 2002 @@ -169,39 +169,19 @@ 0x8a, 0x8a, 0x6a, 0x6a, 0xea, 0xea, 0x2a, 0x2a }; -#define NCOEFF 16 /* number of frequencies to be analyzed */ -#define DTMF_TRESH 25000 /* above this is dtmf */ +#define NCOEFF 8 /* number of frequencies to be analyzed */ +#define DTMF_TRESH 4000 /* above this is dtmf */ #define SILENCE_TRESH 200 /* below this is silence */ -#define H2_TRESH 20000 /* 2nd harmonic */ #define AMP_BITS 9 /* bits per sample, reduced to avoid overflow */ #define LOGRP 0 #define HIGRP 1 -typedef struct { - int grp; /* low/high group */ - int k; /* k */ - int k2; /* k fuer 2. harmonic */ -} dtmf_t; - /* For DTMF recognition: * 2 * cos(2 * PI * k / N) precalculated for all k */ static int cos2pik[NCOEFF] = { - 55812, 29528, 53603, 24032, 51193, 14443, 48590, 6517, - 38113, -21204, 33057, -32186, 25889, -45081, 18332, -55279 -}; - -static dtmf_t dtmf_tones[8] = -{ - {LOGRP, 0, 1}, /* 697 Hz */ - {LOGRP, 2, 3}, /* 770 Hz */ - {LOGRP, 4, 5}, /* 852 Hz */ - {LOGRP, 6, 7}, /* 941 Hz */ - {HIGRP, 8, 9}, /* 1209 Hz */ - {HIGRP, 10, 11}, /* 1336 Hz */ - {HIGRP, 12, 13}, /* 1477 Hz */ - {HIGRP, 14, 15} /* 1633 Hz */ + 55813, 53604, 51193, 48591, 38114, 33057, 25889, 18332 }; static char dtmf_matrix[4][4] = @@ -499,6 +479,18 @@ sk2 = sk1; sk1 = sk; } + /* Avoid overflows */ + sk >>= 1; + sk2 >>= 1; + /* compute |X(k)|**2 */ + /* report overflows. This should not happen. */ + /* Comment this out if desired */ + if (sk < -32768 || sk > 32767) + printk(KERN_DEBUG + "isdn_audio: dtmf goertzel overflow, sk=%d\n", sk); + if (sk2 < -32768 || sk2 > 32767) + printk(KERN_DEBUG + "isdn_audio: dtmf goertzel overflow, sk2=%d\n", sk2); result[k] = ((sk * sk) >> AMP_BITS) - ((((cos2pik[k] * sk) >> 15) * sk2) >> AMP_BITS) + @@ -522,28 +514,58 @@ int grp[2]; char what; char *p; + int thresh; while ((skb = skb_dequeue(&info->dtmf_queue))) { result = (int *) skb->data; s = info->dtmf_state; - grp[LOGRP] = grp[HIGRP] = -2; + grp[LOGRP] = grp[HIGRP] = -1; silence = 0; - for (i = 0; i < 8; i++) { - if ((result[dtmf_tones[i].k] > DTMF_TRESH) && - (result[dtmf_tones[i].k2] < H2_TRESH)) - grp[dtmf_tones[i].grp] = (grp[dtmf_tones[i].grp] == -2) ? i : -1; - else if ((result[dtmf_tones[i].k] < SILENCE_TRESH) && - (result[dtmf_tones[i].k2] < SILENCE_TRESH)) + thresh = 0; + for (i = 0; i < NCOEFF; i++) { + if (result[i] > DTMF_TRESH) { + if (result[i] > thresh) + thresh = result[i]; + } + else if (result[i] < SILENCE_TRESH) silence++; } - if (silence == 8) + if (silence == NCOEFF) what = ' '; else { - if ((grp[LOGRP] >= 0) && (grp[HIGRP] >= 0)) { - what = dtmf_matrix[grp[LOGRP]][grp[HIGRP] - 4]; - if (s->last != ' ' && s->last != '.') - s->last = what; /* min. 1 non-DTMF between DTMF */ - } else + if (thresh > 0) { + thresh = thresh >> 4; /* touchtones must match within 12 dB */ + for (i = 0; i < NCOEFF; i++) { + if (result[i] < thresh) + continue; /* ignore */ + /* good level found. This is allowed only one time per group */ + if (i < NCOEFF / 2) { + /* lowgroup*/ + if (grp[LOGRP] >= 0) { + // Bad. Another tone found. */ + grp[LOGRP] = -1; + break; + } + else + grp[LOGRP] = i; + } + else { /* higroup */ + if (grp[HIGRP] >= 0) { // Bad. Another tone found. */ + grp[HIGRP] = -1; + break; + } + else + grp[HIGRP] = i - NCOEFF/2; + } + } + if ((grp[LOGRP] >= 0) && (grp[HIGRP] >= 0)) { + what = dtmf_matrix[grp[LOGRP]][grp[HIGRP]]; + if (s->last != ' ' && s->last != '.') + s->last = what; /* min. 1 non-DTMF between DTMF */ + } else + what = '.'; + } + else what = '.'; } if ((what != s->last) && (what != ' ') && (what != '.')) { diff -urN -X dontdiff linux-2.4.20/drivers/isdn/isdn_audio.h linux-2.4.20.mod/drivers/isdn/isdn_audio.h --- linux-2.4.20/drivers/isdn/isdn_audio.h Fri Dec 21 18:41:54 2001 +++ linux-2.4.20.mod/drivers/isdn/isdn_audio.h Mon Dec 16 17:42:32 2002 @@ -20,6 +20,7 @@ typedef struct dtmf_state { char last; + char llast; int idx; int buf[DTMF_NPOINTS]; } dtmf_state; --nextPart1113440.8i0y9mmqF5-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/