[mythtv-users] saa7134 mute issue

[Brian Perkins]

So I think I figure out what the issue is.

This comment:
http://archives.devshed.com/forums/linux-97/digimatrix-saa7134-audio-issue-2082390.html
suggests that the detection of NTSC audio formats isn't 100% reliable.

To fix this you can set the saa7134 module parameter "audio_ddep" to 
either 0xc,0xd or 0xe.  Mine seems to work for 0xd, where I seem to get 
reliable stereo audio (0xc gives me mono only, I didn't try 0xe).

I'm not quite sure I understand what this is doing, but hopefully it 
solves the problem.


Brian Perkins wrote:
> So I have a weirder than usual saa7134 mute issue.
> 
> About 5% of the time my recordings have no sound.
> 
> I've been experiencing this issue ever since I started using my Lifeview 
> flyvideo card, mythtv .17 and kernel 2.6.14.
> 
> It took me a while to figure out what was going on, but if I patiently 
> change channels until I get no sound I've found a couple of things:
> 
> When there is sound :
> /usr/bin/v4lctl -c /dev/video0 volume mute off
> will toggle the sound
> 
> and
> /usr/bin/v4lctl -c /dev/video0 list
> 
> shows the input is "Television"
> 
> In the case that there is no sound:
> 
> Using
> /usr/bin/v4lctl -c /dev/video0 volume mute off
> 
> has no effect.
> 
> The TV input is set to "TV (mono only)" .  Using v4lctl to switch it to 
> "Television" and then shutting off mute restores the sound.  The default 
> input in mythtvsetup in the input connections dialog is "Television", so 
> I don't understand why it gets set to TV mono.
> 
> I guess I could write a custom script to change the channel by hand and 
> check that the input is correct, but that seems like a hassle.  I could 
> also write a daemon to check the status of the input and switch it, but 
> constantly polling the status of the input card seems messy.
> 
> Has anyone experienced this problem and knows a work-around?
> 
> My setup:
> 
> mythtv-0.20.2-168.fc7 from atrpms
> kernel 2.6.21-1.3194.fc7 (I'm hesitent to upgrade because I had issues 
> with the NVIDIA module causing hard hangs)
> Liveview Flyvideo 3000 (so says mythsetup anyway)
> analog cable irc
> 
> Thanks
> 
> Brian
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