[pvrusb2] no audio with PAL and tda9887

[Mike Isely]

On Fri, 30 Dec 2005, Michael Roitzsch wrote:

> Hi Mike,
>
>> As for the tda9887 problem, I'm at a loss to suggest anything beyond what 
>> you're already tried.  I'll look at your log output again and see if I can 
>> suggest anything new.  Also did you look at the FAQ and check the usual 
>> list of suspects for when there isn't any sound?
>
> I think so. The msp3400 is loaded and I tried toggling the mute control in 
> sysfs and played with the volume and the various other audio settings, but 
> nothing changed.
>
> Unfortunately, I could not get the driver working in Windows (just Win98 
> here). The device works somewhat on the Mac. At least I get some audio out of 
> it (so I don't think the box itself is broken), but sound and picture are 
> distorted. I believe the Mac driver was written with only NTSC in mind and 
> does not handle PAL properly.
>
> If it might help I could try getting my hands on an XP to sniff the USB 
> transfers on Windows, but I don't have any experience in that.

Actually sniffing the traffic in Windows (when it is working) would be 
very helpful.  If you look at http://www.isely.net/pvrusb2-utils.html you 
can see basically how to do that.  Having a chunk of the traffic will show 
us how the Windows driver is programming the tda9887 (among other things) 
and I can use that to figure out what is different.  I wrote a C++ program 
which can interpret all the USB traffic into the actual chip level 
commands being issued (see that web page for info).  If you want to try 
this, I'll need to send you a slightly updated decode_log.cpp source file. 
The version in the 20051226 snapshot doesn't parse out tda9887 commands; 
the next snapshot released will have the updated utility.


>
> Btw, does the device normally disable sound by itself unless the channel is 
> tuned in properly (so you don't hear the static)?

There's nothing in the pvrusb2 driver to specifically disable sound if the 
tuning isn't right.  However if the tuning is not close enough, the the FM 
carrier for the audio won't be sensed by the hardware and thus no sound. 
My understanding is that with PAL one of the first symptoms of bad tuning 
is no sound.  For me in NTSC I usually always get sound but instead I lose 
the colorburst signal (and thus get B&W video) if my tuning is too far 
off.

I did look back at your log output, and found nothing else to suggest a 
problem.

   -Mike


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