Re: [Discuss-gnuradio] Distorted playback of real-time audio on Linux

[Elvis Dowson]

Hi Alex,

On Aug 13, 2010, at 12:39 PM, Alexandru Csete wrote:

Maybe it is a driver issue. I suppose your iMac is the latest
generation (late 2009?) but the distributed alsa drivers are usually
older.

Yes, my iMac 27" is a late 2009 model. 

$ sudo dmidecode -s system-product-name

  iMac11,1

You can check how the hardware is detected in the hardware tab of the
audio settings or "lspci | grep Audio" and see how it fits with what's
actually in the computer.

The following commands show the various hardware and codec installed on the iMac. I'm running it natively on the iMac 27 at the moment. 

Install required packages to enable audio.

$ sudo apt-get install linux-backports-modules-alsa-lucid-generic gnome-alsamixer

Find the Sound card model

cat /proc/asound/card0/codec#0 | grep Codec

Codec: Cirrus Logic CS4206

List all the audio PCI devices connected to the system

$ sudo lspci | grep Audio

00:1b.0 Audio device: Intel Corporation 5 Series/3400 Series Chipset High Definition Audio (rev 06)

01:00.1 Audio device: ATI Technologies Inc HD48x0 audio

Modify the alsa-base.conf file. 

$ sudo gedit /etc/modprobe.d/alsa-base.conf

options snd-hda-intel power_save=10 power_save_controller=N model=imac27

For the Cirrus Logic CS4206/4207 chipset, the snd-hda-intel driver options parameter for the model is imac27

Do you think the two are matched? 

Best regards,

Elvis Dowson