[linux-dvb] HVR3000, cx88_alsa (audio not crackly)

Robert Longbottom RobertCL at iname.com
Tue Jan 9 09:45:39 CET 2007

On Mon, January 8, 2007 3:11 am, Simon Bazley wrote:
> I had a job getting sound to work properly (without and clicking, delays
> or other resampling errors) from sox or arecord & aplay.
> eventually this worked:-
> mplayer tv://25 -tv
> driver=v4l2:device=/dev/video0:norm=PAL-I:chanlist=europe-west:\
>                     alsa:adevice=hw.2,0:amode=1:audiorate=48000:volume=100:\
>                     immediatemode=0:buffersize=32 -aspect 16:9
> Where My SkyBox is tuned to channel 25, its /dev/video0 its PAL-I
> (europe-west) and the cx88_alsa device is card2 sub 0 (ie hw.2,0).  I want
> sound in
> stereo (amode=1) at 48k.  I had problems with buffers overflowing, so I
> set the buffersize to twice what was needed and the sound is now perfect.
> My SkyBox is setup for a 16:9 screen, even though PAL-I isn't so the
> -aspect 16:9 corrects the screen size.
> I've be curious to know what command you were using to pass through the
> audio?  Is there a better way than mplayer?  I couldn't get sox or
> arecord/aplay to work satisfactorly.

Interesting.  I decided to have a play around with mine last night to try
and fix the audio problems I've been having.  I think I've managed to cure
them, but I'm not really sure how.  I now have:

    options cx8xx i2c_scan=1 nicam=1

in modules.conf.  That seems to have helped the audio in some way.  I
think my remaining problems on one or two channels is due to the fine tune
needing tweaking in mythtv.

I think also, the problems I was having before with crackly audio were
because while I was recording I was using 100% CPU (for an unrelated
reason) and I've also tweaked the capture resolution which seems to have
improved picture quality.

I'll try to give your mplayer command a go and see what happens.  In the
past I think I've had arecord/aplay working reasonably with similar
settings to what you have about (stereo, 48k).


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