[pvrusb2] mythtv and wintv-hvr-1950 - analog/digital scanning

Tue Jan 6 18:09:33 CST 2009

Just a stab in the dark but could it be a permissions error on the file
/dev/video0 ?  I've had some weird things happen where I didn't have the
correct permissions trying to open the video from Mythbuntu 8.10.  I tried
the shotgun approach and did a chmod on the video0 with 777 to allow
everything access just to test.  This worked for me.

On Tue, Jan 6, 2009 at 3:09 PM, fivenote <fivenote at gmail.com> wrote:

> Great tips. Here's what I found...
>
> I disabled mythtvbackend and used sysfs interface to control the
> driver. I also confirmed it is creating /dev/video0.
>
> The enum_val shows all 4 inputs (dtv, television, composite, svideo).
> For fun I restarted mythbackend and mythtv and watched enum_val narrow
> successfully between dtv and television. DTV signal came through, but
> still no television signal came through.
>
> I disabled mythtvbackend again and checked sysfs. All four inputs
> showed, meaning nothing was left open and narrowed.
>
> I switched cur_val to 'composite' and hooked up a video player to the
> HVR-1950's composite input. mplayer still didn't work. I tried xine
> and it says "There is no demuxer plugin available to handle
> '/dev/video0'. I'll try to figure out what that is. Any hints are
> welcome.
>
> Meanwhile... fyi... When I installed v4l drivers, it had it's own
> pvrusb source and replaced the one I downloaded from Mike's site. Is
> there a difference between the pvrusb2 source at Mike's site and
> LinuxTV? Which is more current. I figure this is worth mentioning so
> we know what source I'm running.
>
> Thanks for all your help. I'm learning more each time and hope to
> figure it out soon.
>
> On Tue, Jan 6, 2009 at 2:18 AM, Mike Isely <isely at isely.net> wrote:
> >
> > Vincent:
> >
> > Additional comments and ideas are laid out below...
> >
> > On Mon, 5 Jan 2009, fivenote wrote:
> >
> >> Thanks.
> >>
> >> I tried running /usr/bin/mythtv-setup.real -v all. Got lots of output
> >> but no obvios problems.
> >>
> >> I went back to basics and tried to get data from the device. I
> >> shutdown mythbackend and did...
> >>
> >> >cat /dev/video0
> >> cat: /dev/video0: Input/output error
> >
> > I'm assuming that /dev/video0 is your device - do an "ls -l /dev/video*"
> > and make sure you get back what you expect, e.g. if there are multiple
> > entries make sure you are talking to the right one.  And there *can* be
> > multiple entries even for a single device if you unplugged the device
> > from the USB spigot while someone was operating it.  In that case, the
> > old /dev/video0 can't go away until the entity hanging onto the open
> > device handle has exited (perhaps some piece of mythtv is still not
> > letting go).  Then when you plug it back in, the "new" instance will
> > become /dev/video1 because /dev/video0 is still allocated to something
> > else (i.e. the previous dying driver instance due to the previous unplug
> > event).
> >
> > But assuming that /dev/video0 is correct...
> >
> > EIO ("Input/output error") will happen if the stream can't be started.
> > This is NOT what happens if you can't receive any video.  In that case
> > the stream will start but you won't receive any data (it will just
> > stall) or you'll receive noise for video (depending on the situation).
> > The fact that you got an EIO strongly suggests that streaming failed
> > because something else already has the device open.  And that something
> > else doesn't have to be someone with /dev/video0 open - it might be a
> > process operating the DVB side of the device.  The HVR-1950 hardware is
> > shared between V4L and DVB so if one side is trying to stream (even if
> > only to acquire a signal lock in the case of DVB) then the other side is
> > kept out of the way.  You said you shut down the mythtv back end, but it
> > sure sounds like that didn't entirely work.  I'll bet you've got
> > something hanging onto the DVB side.
> >
> > Try cat'ing /sys/class/pvrusb2/*/ctl_input/enum_val and see what input
> > choices are in the list.  If you're only seeing "dtv" that means the
> > input selection has been narrowed because the DVB interface is active -
> > somebody is accessing it.  That would explain the behavior you are
> > seeing.  To understand what I mean about "narrowing", go here:
> >
> > http://www.isely.net/pvrusb2/usage.html#Interactions
> >
> > and then scroll down to the section titled "V4L vs DVB interactions".
> >
> >
> >>
> >> and...
> >>
> >> > mplayer /dev/video0
> >> MPlayer 1.0rc2-4.3.2 (C) 2000-2007 MPlayer Team
> >> CPU: Intel(R) Core(TM)2 Duo CPU     T5450  @ 1.66GHz (Family: 6,
> >> Model: 15, Stepping: 13)
> >> CPUflags:  MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
> >> Compiled with runtime CPU detection.
> >>
> >> Playing /dev/video0.
> >> Win32 LoadLibrary failed to load: avisynth.dll,
> >> /usr/lib/win32/avisynth.dll, /usr/local/lib/win32/avisynth.dll
> >>
> >>
> >> Exiting... (End of file)
> >> -------
> >>
> >> Both of these used to work before I updated to the latest v4l drivers.
> >> I don't know what else to try.
> >>
> >
> > However we really need here to separate questions of what is going on in
> > MythTV versus what is going on in the driver.  You are raising issues
> > and we can't tell who is causing what.  I think given the confusion you
> > are experiencing that you should unambiguously kick the applications out
> > of the way and focus your attention purely on the driver.  Only then,
> > after we know the driver is healthy, should you bring MythTV back into
> > the puzzle.  So do this:
> >
> > 1. Disable the mythtv backend from even starting (i.e. rename the binary
> > so that a system boot script can't start it without your knowledge).
> >
> > 2. Unplug the HVR-1950 from the USB port.
> >
> > 3. Reboot your system.
> >
> > 4. Plug in the HVR-1950.
> >
> > The idea for the above is not so much to reset the hardware but to start
> > up in a way that gives high confidence that nobody is trying to access
> > the device "behind your back".  Everything should come up clean and
> > nobody should be trying to use the device, DVB or V4L.
> >
> > Now run through some of the usual tests with the V4L side.  Try mplayer
> > while using the syfs interface to control the input selection and tuning
> > frequency (again, see the above page for information about those
> > interfaces).  If after that you are still having analog tuning problems,
> > peel back another layer: plug a composite video source into the device
> > (VCR, DVD player, camcorder, etc) and try to stream from that input.
> > An operation like that does not require a working RF tuner.  If that
> > works, then we know at least everything except the RF tuner is ok.  Do
> > all that first and you can verify that you have working analog hardware.
> >
> > Then try a simple DVB application for the DVB side.  Verify that works.
> >
> > If you get past those steps then you've confirmed that the hardware is
> > healthy and the pvrusb2 driver and all the various related V4L & DVB
> > software bits are all working correctly.  Then turn your attention back
> > to MythTV and debug that...
> >
> >  -Mike
> >
> > --
> >
> > Mike Isely
> > isely @ pobox (dot) com
> > PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8
> > _______________________________________________
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> > pvrusb2 at isely.net
> > http://www.isely.net/cgi-bin/mailman/listinfo/pvrusb2
> >
>
>
>
> --
> ~~~~~~~~~~~~~~~~~~~~
> VAO - fivenote at gmail.com
> ~~~~~~~~~~~~~~~~~~~~
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