9 Mar
2006
9 Mar
'06
11:28 a.m.
Hello List,
I'm new to audio programming and have problems finding the right
solutions for the development I work on right now:
I need to use the left and the right audio channel seperately. The
device is an ARM based board with a AC97 soundchip. It seems to work
with OSS so far and I did choose libsdnfile to open Soundfiles and get
the PCM. As far as I learned the audio data is coded in one stream,
one sample left, one sample right. Is there a way to separately fill
the soundcard buffers with ALSA?
The only solution I can think of right now is to recode the audio
data to left only or right only and to use a library like esound to
mix them together. Is this the right way to do such a thing?
Any suggestions, pointers, hints are highly welcome.
Greetings,
Tobias
9 Mar
9 Mar
11:53 a.m.
New subject: [linux-audio-dev] Writing PCM to left and right channel sperately?
On Thu, 2006-03-09 at 16:28 +0100, Tobias Scharnberg wrote:
Hello List,
I'm new to audio programming and have problems finding the right
solutions for the development I work on right now:
I need to use the left and the right audio channel seperately. The
device is an ARM based board with a AC97 soundchip. It seems to work
with OSS so far and I did choose libsdnfile to open Soundfiles and get
the PCM. As far as I learned the audio data is coded in one stream,
one sample left, one sample right. Is there a way to separately fill
the soundcard buffers with ALSA?
many.
The only solution I can think of right now is to
recode the audio
data to left only or right only and to use a library like esound to
mix them together. Is this the right way to do such a thing?
esound is not a library for mixing.
what type of application are you writing?
12:02 p.m.
Hello Paul
2006/3/9, Paul Davis <paul(a)linuxaudiosystems.com>om>:
What do you mean - there are many ways when using ALSA or are there
also ways when using OSS. I know - this is RTFM worthy - but I have no
time for that, so a pointer would be very helpful!
As far as I
learned the audio data is coded in one stream,
one sample left, one sample right. Is there a way to separately fill
the soundcard buffers with ALSA?
many. esound is not a library for mixing.
OK, its a sound server.
what type of application are you writing?
The application has to play back automated announcements on a
amplifier/speaker system but it has to be able to play 2 different
announcements at the same time - one on the left and one on the right
channel.
Tobias
12:25 p.m.
New subject: [linux-audio-dev] Writing PCM to left and right channel sperately?
On Thu, 2006-03-09 at 17:01 +0100, Tobias Scharnberg wrote:
you just take one of the example ALSA PCM apps. they typically configure
the h/w for stereo, interleaved output, often 16 bit samples. then you
just need an array of 16 bit samples, and you write the left/right
samples into alternating entries in the array. write the array. done.
--p
What do you mean - there are many ways when using ALSA
or are there
also ways when using OSS. I know - this is RTFM worthy - but I have no
time for that, so a pointer would be very helpful!
if you use OSS the kernel will print a message complaining about your
application. OSS is an officially deprecated API, and you should not use
it.
what type of
application are you writing?
The application has to play back automated announcements on a
amplifier/speaker system but it has to be able to play 2 different
announcements at the same time - one on the left and one on the right
channel. 
10 Mar
10 Mar
6:06 a.m.
Tobias Scharnberg wrote:
I need to use the left and the right audio channel
seperately.
If you're using the ALSA library, you can use the following definitions
in /etc/asound.conf or ~/.asoundrc to get two independent virtual
devices:
pcm.left {
type plug
slave.pcm {
type dshare
ipc_key 12345
slave.pcm "hw:0,0"
slave.channels 2
bindings {
0 0
}
}
}
pcm.right {
type plug
slave.pcm {
type dshare
ipc_key 12345
slave.pcm "hw:0,0"
slave.channels 2
bindings {
0 1
}
}
}
HTH
Clemens
6778
days inactive
6779
days old
linux-audio-dev@lists.linuxaudio.org
4 comments
3 participants
participants (3)
-
Clemens Ladisch -
Paul Davis -
Tobias Scharnberg