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Getting sound to work with cx88-alsa
PostPosted: Sat Sep 23, 2006 9:50 am Reply with quote
Joined: 02 Sep 2006
Posts: 3


I've successfully used the HD5500 card for a few months now, and was trying to enable the cx88-alsa module to capture sound directly with analog mode instead of through the pass through cable. (My audio seems to capture with pops and thought this might be a solution).

I've been able to load the cx88-alsa module as part of my alsa configuration and have the /dev/dsp2 that I specified. I've also checked it with alsamixer and it exposes and single capture control that is not muted and has volume turned up. But all I get when I try and use the /dev/dsp2 in mythtv is static. BTW, I've run lspci -n and verified that I have the [Audio Driver] exposed on my card.

was wondering if anyone here can help. Here's a lot of relevant details about my setup:

Gentoo 2006.0 system running the gentoo 2.6.18-gentoo kernel. I've got alsa and the cx88 drivers compiled as modules using the versions that ship with the 2.6.18 kernel. I'm using the gentoo standard /etc/init.d/alsasound scripts to start alsa on boot and have the following configured in my /etc/modules.d/alsa file:

alias char-major-116 snd
alias char-major-14 soundcore

#Card 1
alias snd-card-0 snd-intel8x0
alias sound-slot-0 snd-card-0

alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss

options snd-intel8x0 index=0

alias /dev/dsp snd-pcm-oss

#Card 2
alias snd-card-1 snd-emu10k1
alias sound-slot-1 snd-card-1

alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-12 snd-pcm-oss

options snd-emu10k1 index=1

alias /dev/dsp1 snd-pcm-oss

#Card 3 - CX88-alsa
alias snd-card-2 cx88-alsa
alias sound-slot-2 snd-card-2

alias sound-service-2-0 snd-mixer-oss
alias sound-service-2-3 snd-pcm-oss
alias sound-service-2-12 snd-pcm-oss

options cx88-alsa index=2

Any ideas? Thanks!
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PostPosted: Wed Sep 27, 2006 7:54 am Reply with quote
Joined: 06 Jul 2006
Posts: 125

Take mythtv out of the mix. Run TVtime and pipe the sound directly from the PCHD5500 to your sound output device using sox and/or aplay/arecord.
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PostPosted: Wed Oct 04, 2006 5:32 am Reply with quote
Joined: 09 Aug 2006
Posts: 8

I've actually given up on the cx88_alsa module. I finally installed another cheapie tv capture card to capture NTSC, and put cx88_alsa on the hotplug blacklist.

I would have spent more time trying to get it working, but found that the NTSC video capture quality was unacceptable- it seemed bright and washed out, and although I could adjust the brightness and contrast (under TVtime, I left myth out of the mix at this point) to make it better, it never looked good.
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Sound, but not good
PostPosted: Sun Oct 15, 2006 9:41 am Reply with quote
Joined: 21 Jul 2006
Posts: 13

I have the analog sound working, but the quality is very bad. It sounds like a 56kbs MP3, with lots of compression artificts. I don't know where to look to see why there is compresion occuring.

The other problem is that in Myth, when switching channels, I lose analog sound.

Running Suse 10.1 Latest myth20.8

When the audio fails, the backend give the following error:

2006-10-15 10:39:20.378 NVR(/dev/video0) Error: DQBUF ioctl failed.
                        eno: Invalid argument (22)
2006-10-15 10:39:26.816 NVR: Only read 1364 bytes of 5456 bytes from '/dev/dsp1
read audio: Success
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PostPosted: Fri Oct 27, 2006 12:34 pm Reply with quote
Joined: 14 Oct 2006
Posts: 3
Location: San Francisco, CA

On the front end, Utilities/Setup - Setup - TV Settings -
Recording Profiles - Software Encoder (v4l based):

in the Live TV setting, last page, make sure it's not set to MP3 for the codec. Change to Uncompressed 48000.
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Getting sound to work with cx88-alsa
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