[mythtv-users] Crackling and popping in non-PVR analog card -- I think I can say it's MythTV's fault

[Sérgio Gomes]

Dewey Smolka wrote:

>
>>- video4linux CVS (due to some cx8800 problems with the release
>>version). --> shouldn't be the problem because of all the above reasons
>>    
>>
>
>Hmmmm. This may be the problem, because the things you mention above
>don't use V4L, at least not that I'm aware of.
>  
>
Well, I really doubt it's the cx8800 driver's fault, since MythTV does 
not get the audio from it, but instead from the soundcard. The sound 
goes from the TV card to the sound card via an external patch cable, and 
is apparently fine when it reaches the sound card, as my numerous 
attempts to play and record it under different conditions have hopefully 
shown.

>So about the only thing that's left is V4L (which AFAIK is used for
>dumb capture rather than hardware encoding) and the card itself.
>Unfortunately, I don't have any experience with V4L or with your card.
>However, I suspect that this is the source of the problem. You may be
>right that it's a multiplexing issue, but if so, it's a result of
>driving your particular card with your particular version of V4L.
>  
>
Still, I don't see how v4l can be affecting the sound in MythTV, since 
MythTV only gets video from v4l...

>Unfortunately, There's not much I can tell you. I can say that
>replacing the card with a PVR x50 (which doesn't use V4L) will
>probably get rid of your problem, but that means spending money.
>Others may be able to help more.
>  
>
Well, I realize that non-PVR cards are not so spectacular, but I was 
hoping it would be enough for watching and recording TV, at least with a 
fast computer, which should be able to do things in software. Maybe I'll 
have to consider that option, though...

>Completely out of the blue, but is it possible that there is an
>NTSC/PAL problem -- like using an NTSC capture card on a PAL signal?
>It's a longshot, but I'm only trying to give you ideas.
>  
>
No, from what I know these cards work with both PAL and NTSC, and anyway 
this card was bought in Europe, which is PAL-only. Still, if everything 
else except for MythTV works fine...

Thanks, you've been a lot of help, really... I've ran a few more tests I 
couldn't think of after reading your comments, like testing full-duplex. 
I still haven't found the problem, but hopefully I'm narrowing it down.
I'm also going to run a few other tests tomorrow. I have an older PC 
with a BTTV card, and I'll set MythTV up there. I'll see if that one 
gets any crackling, if it plays recordings from this PC with or without 
crackling, and also if this PC plays recordings from the other one with 
or without any crackling. That will hopefully narrow it down to either 
playback or recording.

Maybe I'll also try swapping TV cards and seeing what happens.

Sérgio Gomes