in alsamixer, look for a "Rec." toggle on the line-in channel. I had this very problem with my i810 compatible (nforce2) onboards sound. On May 13, 2004, at 9:03 AM, Malcolm Baldridge wrote: > A few weeks into my admittedly bizarre Jack-based telephone logging + > music-on-hold system, I ran into an interesting "bug". > > But first, the hardware in play: > > Motherboard: ECS P4IBMS (Pentium 4, i845 chipset) > > 00:1f.5 Multimedia audio controller: Intel Corp. 82801BA/BAM AC'97 > Audio > Card: Intel 82801BA-ICH2 > > Chip: Realtek ALC200/200P rev 0 > > ALSA-1.0.3b w/1.0.4 drivers + libraries, jackd is from late April 2004 > CVS. > > My jackd invocation line is as follows: > jackd -R -d alsa -S -C -p 4096 -M -n 2 -r 11025 > > I have an AT&T MERLIN phone system in my closet along with my main home > server (see above hardware description). I have my PCM (Line out) > plugged > into the MERLIN system's music-on-hold port, that works well. > > I have two phone lines hooked up to JD Audio Phone Patch boxes to > provide > local + remote side level correction (trans-hybrid technology), which > feeds > into my Line In jack [each patch box provides a mixed in/out audio > source on > a mono output, so I have Line 1 feeding Left, and Line 2 feeding > Right]. > This too works beautifully with my vox-activated audio logging program > which > I'd adapted from one of the jackd sample clients. [It's ended up quite > something else, but not too bad if I say so myself.] > > PROBLEM: When I have someone on hold on Line 2, say, and someone else > is > talking on Line 1, the person on Line 2 hears the music-on-hold *AND* > the > conversation of Line 1!! > > It gets better. If I dial out on Line 3 [lines 3+4 are outbound > only], put > that call on hold, and there are people talking on Lines 1+2, the > caller at > the other side of Line 3 hears not only the music-on-hold, but BOTH > Line 1 + > 2's conversations!!! > > YIKES!!! This was a big shocker. Naturally, I never did this sort of > testing, being more concerned with DC bias, filtering curves and > bandpass > settings, and which compressors to use for the online-browsable > phonelogs as > well as the losslessly-compressed (FLAC of course) data archival logs. > > Obviously the PCM output is being mixed into whatever feeds into the > Line > input of the AC97 codec. This is annoying, and I can see no way of > switching it off. I've explored every Mute/on/off option in the > alsamixer, > alas the dark fire did not avail me. > > I see nothing about "hardware monitoring" as an option for this > chipset, > however Hammerfall and others are mentioned as supporting this feature; > nothing in the intel-8x0 driver suggest this is a supported feature. > > I'm relatively new to PC audio hardware, but has the LINE-IN been fed > into > the PCM output mixer from the beginning? Is this a funky chipset bug > or > weird issue or interaction? I know that the output mixer is fed audio > from > the CD and the WAVE device, but it seems a bit strange that the > LINE-IN port > is also routed through in this way. I can't try this under Windows, > as this > machine has been kept clean from the Dark Software of Ud?n since its > deployment. > > I obviously can't mute the PCM output, since that's the music-on-hold. > > After much experimentation, I figured I'd try the Microphone input > instead. > It seems noisier, even with the +20dB turned off. The impedance is > quite a > bit different, though fortunately I can get by with the gain set to > the bare > minimum [3 in the ALSA mixer, which is the smallest non-zero value I'm > allowed]. But the cross-surveillance bonus to the music-on-hold > problem is > gone. > > Maybe I can do something tricksy like emit the music-on-hold on the > right > channel only, and hook up Line 2's audio feed into the left channel of > the > LINE-IN. This is a cruel hack which depends on the mic+mix functions > in the > codec doing their job properly, which is a huge ask. Ah well. > > I'm back in action, only now I have only one channel of recording > capability. :( :( > > Is there a mixer option/setting to disable this "pass-through" routing > of > LINE-IN to the LINE-OUT sound port? > > In Mordor where the PC platform lies, > > =MB= > > -- > A focus on Quality.
