[pvrusb2] Intermittent video stream damage

[Bjorn Danielsson]

Once in a while I get an unusable video stream, and I want to ask
here if anyone else has seen the same symptoms. I start streaming
and get both video and sound, but the video is extremely "jerky"
with mplayer, as if everyone in the picture has severe chronic
spasms, including the furniture sometimes...

I have seen this happen a couple of times per month, and usually I
just stop the streaming and restart (re-open /dev/video0) and then
the problem goes away. But I am worried that this might happen while
recording something. This has fortunately not happened yet, or perhaps
unfortunately because a saved broken MPEG would really make it easier
to debug this. But I did manage to catch the output from an affected
mplayer process recently:

AO: [alsa] 48000Hz 2ch s16le (2 bytes per sample)
Starting playback...
VDec: vo config request - 720 x 576 (preferred colorspace: Planar YV12)
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.33:1 - prescaling to correct movie aspect.
VO: [xv] 720x576 => 768x576 Planar YV12 
[mpeg2video @ 0xb90c60]ac-tex damaged at 7 0
[mpeg2video @ 0xb90c60]00 motion_type at 8 1
[mpeg2video @ 0xb90c60]00 motion_type at 4 2
[mpeg2video @ 0xb90c60]mb incr damaged
[mpeg2video @ 0xb90c60]00 motion_type at 5 4
[mpeg2video @ 0xb90c60]slice mismatch
[mpeg2video @ 0xb90c60]00 motion_type at 25 6
[mpeg2video @ 0xb90c60]ac-tex damaged at 0 7
[mpeg2video @ 0xb90c60]invalid cbp at 2 8
[mpeg2video @ 0xb90c60]00 motion_type at 2 9

and it kept going on like that. The pvrusb2 driver in this case is
the one bundled with linux-2.6.26.2.

I can't be sure of course that these broken video streams have
anything to do with the pvrusb2 driver, but I think I have already
excluded some of the more "obvious" failure modes, because I know that:

 + The problem has occurred on two different pvrusb2 hardware devices
 + This never happened when I used the old libusb userspace driver
 + This never happens when I stream DVB-T to mplayer via the same software

Don't we all love intermittent failures? :-)

-- 
Bjorn Danielsson  <pvr-usb2 at dax.nu>