hi is it possible to mute the playthrough/(monitoring) when you re using "live" input on linux & oss drivers? tks,oss
On Fri, 12 Feb 1999, |L_| wrote:
hi is it possible to mute the playthrough/(monitoring) when you re using "live" input on linux & oss drivers? tks,oss
-- 1337777.16662735
Yes, basically it should be possible. Yet, I have not seen a mixer implementation which has this feature. The second problem is that not all soundcards seem to support this feature, and the third that not all soundcard drivers implement this feature.
I am attaching a small program which should mute the recording monitor ...
compile it with gcc -o mute_mon mute_mon.c
and pray .....
Guenter
mute_mon.c
#include <stdio.h> #include <linux/soundcard.h>
char* mix_dev = "/dev/mixer";
main() { int fd; int res; int param=0;
fd = open (mix_dev);
if (fd <0) {
fprintf(stderr,"Could not open mixer device %s\n",mix_dev);
exit(0);
}
res = ioctl(fd,SOUND_MIXER_READ_DEVMASK,¶m);
if (res < 0) fprintf(stderr,"Mixer ioctl failed - No mixer present ?\n");
fprintf(stderr,"Devices supported = %x\n",param);
if (param&SOUND_MIXER_IMIX)
fprintf(stderr,"Can change recording monitor\n");
else
fprintf(stderr,"Unable to change recording monitor\n");
param = 0;
res = ioctl(fd,SOUND_MIXER_WRITE_IMIX,¶m);
if (res < 0) fprintf(stderr,"Muting recording monitor failed\n");
else fprintf(stderr,"Recording monitor muted\n");
}
Hello,
Can anyone point me to information on calculating the dynamic placement of sound within an 8-channel speaker matrix? The speakers would be set in a evenly-spaced circle around the listening space and I'd like to be able to dynamically and arbitrarily move sounds within this space using the matrix calculations to control routing to the 8 outputs. I'd also like to be able to place stereo input in this space maintaining and distorting the original spread image within the 8-channels.
Any help is greatly appreciated.
Bill Kleinsasser
Hi Bill,
this dynamic sound placement is something that I have been working with on and off for a while. I presume you would like to be able to place sound arbitrarily inside the surface that the speakers enclose. This is a bit harder than placement around the ring of speakers.
The ring placement is basically a pan between the two speakers, a linear fade as opposed to a log fade used for levels. This little note is trivial when you know it, which you probably do, but vital if you dont, so I thought it good to make sure you do.
This is easy and fast, we have done a bunch of work with some equipment and sound movement using rotation as a main theme.
The placement on a surface is more dependent upon the precise arrangement in space of the surrounding triangle of speakers. I have done calculations for speakers on a regular square grid, to place a sound anywhere on that grid, but I dont have them with me. It's a bit of trigonometry and a bit complex, but nothing too much.
The sound sources we found had to have certain properties, most importantly was a lack of resonance. Most effective was some pure noise, Japanese stuff or John Duncan sort of noise tracks. Pure tones resonate too well and envelop the space. Percussivity was also a little distracting, depending upon the speed of movement relative to the beat rate. One has to ensure that the sound source doesn't disappear at one point and reappear elsewhere, unless that is the desired effect.
This is, of course, all work very much in progress, so I would love to hear about your and other people's experiences with other techniques.
Cheers,
tim
\ / TIME´S UP \ / Industriezeile 33 B -------------------------------------------- / A-4020 Linz Tim Boykett /\ ph:+43/732-787804 tim@bruckner.stoch.uni-linz.ac.at /xx\ fax: +43/732-795742 -------------------------------------------- /xxxx\ http://www.timesup.org
In message 36C8F5E3.7CF22D10@towson.edu, Bill Kleinsasasser bill@towson.edu writes
Hello,
Can anyone point me to information on calculating the dynamic placement of sound within an 8-channel speaker matrix? The speakers would be set in a evenly- spaced circle around the listening space and I'd like to be able to dynamically and arbitrarily move sounds within this space using the matrix calculations to control routing to the 8 outputs. I'd also like to be able to place stereo input in this space maintaining and distorting the original spread image within the 8- channels.
Any help is greatly appreciated.
Bill Kleinsasser
The simplest and most elegant way is to use ambisonic technique. For a two dimensional array you need only three components; X, Y and W (the Z [vertical] component is only used in three dimensions.
It is very easy to generate these components and also to decode them for any number of speakers. I have implemented them on ISPW, so they should be easy in pd. All the formulae can be found in:
Malham and Myatt, 3-D Sound Spatialisation using Ambisonic Techniques, CMJ Vol 19 No 4, Winter 1995
Best
Lawrence Casserley
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Bill Kleinsasasser -
guenter geiger -
Lawrence Casserley -
Tim Boykett -
|L_|