[pvrusb2] Hauppauge HVR-1900 - PAL-Nc, no audio

[Mike Isely]

Dermot:

Actually I think you were on the right track.

ALSA has nothing to do with capture of audio into the MPEG output file.  
Of course, ALSA may have everything to do with playback on your 
computer, but if there's already no audio in the MPEG file itself 
(easily proven by trying to play the file on multiple different 
computers), then ALSA is not involved.

In times past when I've dealt with bugs involving "no captured audio", 
the usual suspect was that the pvrusb2 hardware was being told to use 
the wrong broadcast standard.  It's possible to choose a standard that 
is "close enough" for, say, video to work but not audio.  There are 
different modulation standards and frequencies for the embedded audio 
and if that is set wrong, then of course there will be no audio.

Making matters somewhat more confusing is that in many cases, the 
hardware can successfully guess the correct audio configuration even 
when the wrong standard is set.  So you can get cases where, for 
example, someone with a 24xxx series device will get working audio using 
standard "XYZ" while someone else in the same country but using a 29xxx 
device with the same "XYZ" standard still won't hear any audio :-(

The pvrusb2 driver does not directly program the audio configuration in 
the capture device.  That job is left to the various chip drivers, e.g. 
cx25840.ko in your case.  What the pvrusb2 driver does do however is to 
communicate the chosen standard out to the various chip drivers; then it 
is up to each chip driver to use that information to create the 
appropriate local configuration in the hardware.

I would give odds that the problem involves use of the wrong video 
standard.  Unfortunately I can't tell you what the "right" one would be.  
But you can certainly experiment with the different choices and see what 
might actually work better.  It generally isn't possible to physically 
"harm" the hardware with a wrong video standard, so I would encourage 
some experimentation...  You can use the pvrusb2 driver's sysfs 
interface to get detailed access to all the possible video standards.

You mentioned that msp3400.ko is loaded - ignore that.  It actually 
isn't used for the HVR-1900, rather audio processing on the HVR-1900 
uses the cx25840.ko driver (which is a combined audio and video 
processor).

  -Mike


-- 

Mike Isely
isely @ isely (dot) net
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