[linux-audio-dev] Problem setting recording level

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Subject: [linux-audio-dev] Problem setting recording level
From: Stephane Letz (letz_AT_grame.fr)
Date: Wed Apr 26 2000 - 11:29:09 EEST

Hi,

I am trying to develop a full-duplex audio application on a system with an
emu10k1 card installed using the OSS API. I need to mix sound played from
files and sounds recorded and transformed in real-time.

To set the record level, i use the following ioctl call :

ioctl (mixer_device, SOUND_MIXER_WRITE(SOUND_MIXER_RECLEV)) to set the
global recording level.

My program then read sound buffers and play them back.

To set the pcm level, i use the following ioctl call :

ioctl (mixer_device, SOUND_MIXER_WRITE(SOUND_MIXER_PCM))

To set the master level, i use the following ioctl call :

ioctl (mixer_device, SOUND_MIXER_WRITE(SOUND_MIXER_VOLUME))

The problem is that the level of real-time sound is very low when mixed
with sound played from files.
I tried to use Line in or Mic in without much difference (Mic in is
better). Audio input (Line or Mic) as well as Line out (PCM or master)
are stereo so i use (I hope correctly) the 256*vol_right+vol_left formula
to compute the volume level.

Any ideas?

Stephane Letz

Grame: Centre National de creation musicale
9, Rue du Garet
69001 Lyon
Tel: 04-72-07-37-00
Fax: 04-72-07-37-01
Web: www.grame.fr

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