[pvrusb2] in-kernel driver & corrupt video

[Rick Immel]

pvrusb2 at isely.net wrote:
> I just got my Slackware distro installed with the 2.6.18.kernel.  I 
> copied the three driver extract files to the /lib/firmware directory 
> for my 24xxx hardware.  I plugged the hardware in and it worked, sort 
> of.  The sound  is good, but the video is corrupted  when using xine 
> or mplayer.   I haven't installed MythTV yet, but there appears to be 
> a problem with the in-kernel driver.  I tested my hardware on another 
> machine running a 2.6.17 kernel, the same firmware, and the standalone 
> driver (20060903).  This configuration presents good audio and video 
> with xine and mplayer.  Has someone else experienced this problem?
Rick Immel
>
> Can you describe the nature of the corruption?  Is it periodic or 
> random?  Is the video breaking up or are you seeing uniform distortion 
> (e.g. colors out of whack)?
>
> Starting with 2.6.18, commands to the mpeg2 encoder are determined by 
> a new kernel module, cx2341x.ko.  That should be the only substantial 
> difference.
>
> Can you try the standalone driver in your 2.6.18 and see if the 
> situation is any different?  I suspect it will be the same, but if it 
> isn't then that's another clue.  To try the standalone driver just 
> build it as you always would and simply rename the kernel-built 
> pvrusb2.ko out of the way.
>
>   -Mike
>
I compiled and installed the standalone driver (20060924).  This solved 
the problem!

The corruption was uniform with colors out of whack and thin blue 
horizontal lines in the video.

This implies that the in-kernel driver has some problem.  Maybe its 
specific to my Slackware distro?
If there is anything more I can send you to help solve this problem, 
please let me know.

Rick Immel


Ah ha!

You're using a 24xxx device.  I'll bet your horizontal capture resolution 
is something other than 720.  Can you tell me what your capture resolution 
is?  There's a problem with 24xxx devices where if the horizontal capture 
resolution is not exactly 720 then the video is corrupted.  The key here 
is that the standalone driver has a fix that forces that value to 720 if 
you're on a 24xxx device.  This fix did not get into the in-kernel 2.6.18 
driver (I just checked it to be sure), thus when you went to the 
standalone driver the problem went away.  This fix should probably go into 
2.6.18.y...


> > 
> > This implies that the in-kernel driver has some problem.  Maybe its 
> > specific to my Slackware distro?
> > If there is anything more I can send you to help solve this problem, 
> > please let me know.
>   

Can you check what capture resolution you are/were using with the 
in-kernel driver?  It's possible to read this back via the sysfs interface 
(look at the web page documentation about sysfs for details).

  -Mike


I re-installed the in-kernel driver and checked the value of /sys/class/pvrusb2/sn-*/ctl_resolution_hor/cur_val.  It was 720.        
The ctl_resolution_ver/cur_val equals 480.  The video is corrupted as described above.  I again installed the standalone driver and these resolution values are the same.  The video is now good again.  So I don't think this is the horizontal capture resolution problem.  Any other ideas?

Rick Immel