[pvrusb2] problem with a hvr-1900

Tomas Hylander tomas.hylander at gmail.com
Fri Sep 10 12:22:33 CDT 2010 

Hi again!
Finally got time to test this, just to hit the wall with "permission denied"
even when running sudo. Ive tried both setting frequency and changing to
s-video.

Gonna try some more, but if you know what Im missing out, please tell me.

Thanks!
/Tomas

2010/9/6 Tomas Hylander <tomas.hylander at gmail.com>

> Thanks Lorne! (and Mike :) )
> Yes, that helped clearing up some things...
> Gonna try it as soon as possible.
>
> /Tomas
>
> 2010/9/6 Lorne Shantz <lorne_shantz at yahoo.com>
>
> Hey Thomas,
>>
>> I hope Mike won't mind me posting this. This is an email from him, so the
>> credit obviously goes to him. It greatly helped me understand. Let me know:
>>
>> There's a "magic" file system area on your Linux system; it is known as
>> "sysfs".  The root of this area starts at the /sys directory.
>> Everything below that point is *not* a real file.  Rather these are
>> "special" files that can be used to do interesting things.  When you
>> open and read one of these files, a special function is dispatched
>> within the kernel that synthesizes the content on-the-fly as you read
>> the "file".  The exact function that is dispatched depends on which file
>> you open.  Similarly, if you write to one of these special files,
>> another function is dispatched in the kernel that receives the data you
>> write and will interpret it in some particular way.  Exactly how that
>> interpretation works depends on the function dispatched and the choice
>> of function dispatched depends on which file you write.
>>
>> So effectively by reading and write various things under /sys you can
>> retrieve information about your system or influence its behavior.  This
>> area is, for example, used by udev to know what devices are really out
>> there.  But it has many many other uses.
>>
>> In the case of the pvrusb2 driver, the path /sys/class/pvrusb2 is the
>> root of an area controlled by the pvrusb2 driver.  And it is laid out in
>> a manner that gives you the ability to directly query and control nearly
>> all the various "knobs" and "switches" within the driver.  Just pick the
>> right file and read it to find the knob's state, or write to that file
>> to change the knob's state.  It's the same access you can get through
>> the V4L API, except in this case the "API" as it were is just the file
>> system.  Thus you don't need any special programs to control the driver
>> - just use "cat" to read one of the files and "echo" to write new
>> values.  The explanation for how these all work can be found here:
>>
>>       http://www.isely.net/pvrusb2/usage.html#sysfs
>>
>> So using that interface you can do things like select the input to
>> stream from.  For example, this will change the device to capture its
>> composite input:
>>
>>       echo "composite" >/sys/class/pvrusb2/*/ctl_input/cur_val
>>
>> To go back to television capture, the command would be:
>>
>>       echo "television" >/sys/class/pvrusb2/*/ctl_input/cur_val
>>
>> You can get a list of what input keywords are legal with:
>>
>>       cat /sys/class/pvrusb2/*/ctl_input/enum_val
>>
>> If you're capturing television input you can set the tuner's frequency
>> in Hz just by writing the frequency to ..../ctl_frequency/cur_val (with
>> "...." being the same prefix shown in the other examples).  The "*" part
>> of the path by the way is just a wildcard; your shell will expand that
>> automatically since you only have a single device attached.
>>
>> This allows you to control the driver without needing a V4L application,
>> thus you can eliminate uncertainties caused by bugs in the app.
>>
>> Now there are two things that sysfs interface cannot do: (1) It can't
>> control the DVB side of the driver (which is a non-issue in our case),
>> and (2) you can't directly stream from it.  However streaming is
>> trivially easy once you have the device configured the way you want -
>> just read the stream data from /dev/video0 using cat.  Let's say you
>> wanted to capture 15 seconds of video from the composite input.  Here's
>> what you can do:
>>
>>       echo "composite" >/sys/class/pvrusb2/*/ctl_input/cur_val
>>       cat /dev/video >/tmp/foo.mpg
>>
>> then wait 15 seconds and hit ^C to break out of the cat command.  Now
>> you should have 15 seconds of video sitting in /tmp/foo.mpg.  You can
>> then use mplayer to play it: "mplayer /tmp/foo.mpg".
>>
>> You can also directly use mplayer in place of the "cat" command as you
>> have already discovered.  However I'd advise against that for the moment
>> because mplayer can do some very confusing things if the video streaming
>> isn't constant - the results will be even more confusing.  By capturing
>> to a file and then playing the file we can rule out any funny business
>> that mplayer might be trying when the stream breaks up.
>>
>> Is that enough to get you going?
>>
>> --- On Sun, 9/5/10, Tomas Hylander <tomas.hylander at gmail.com> wrote:
>>
>> > From: Tomas Hylander <tomas.hylander at gmail.com>
>> > Subject: Re: [pvrusb2] problem with a hvr-1900
>> > To: "Communications nexus for pvrusb2 driver" <pvrusb2 at isely.net>
>> > Date: Sunday, September 5, 2010, 9:57 AM
>> > Hi!
>> > Thanks for your reply.
>> > Im sorry I missed out that it is the analog-part of the
>> > hvr-1900 Im trying
>> > to get going.
>> > Im running a dual-core Atom mini-itx with Nvidia ION
>> > graphical board. On
>> > this Ive installed latest Mythbuntu based on Ubuntu
>> > 10.04lts. So the system
>> > should be up to-date.
>> >
>> > Ive read somewhere how to change inputmode (s-video) on
>> > vlc, but now when I
>> > need it I cant find it :(  Do you know?  I tried
>> > looking into yours sysfs
>> > but must say I didnt understood how to use it (I did find
>> > it on my drive
>> > tho).
>> >
>> > Im using kernal  2.6.32-24generic.
>> >
>> > Thanks in adance.
>> > /Tomas
>> > .
>> > .2010/9/3 Mike Isely <isely at isely.net>
>> >
>> > > On Fri, 3 Sep 2010, Tomas Hylander wrote:
>> > >
>> > > > Hi
>> > > > Have been trying to get my hvr-1900 to work but
>> > it looks like I cant get
>> > > it
>> > > > to change channel.
>> > >
>> > > In digital mode or analog mode?  The mechanism is
>> > different in the two
>> > > cases.
>> > >
>> > > In analog mode, the application has to use the V4L API
>> > (i.e. open
>> > > /dev/video0) to change the "channel", and what you're
>> > setting is the
>> > > direct frequency for the channel you want (the
>> > application, e.g. mythtv,
>> > > and to maintain the mapping between channels and
>> > frequencies).
>> > >
>> > > -In digital mode, the application has to use the DVB
>> > API (i.e. stuff
>> > > related to "/dev/dvb/...") to change the channel, and
>> > the notion of
>> > > "channel" there is entirely contained in the DVB
>> > subsystem not the
>> > > pvrusb2 driver.  With ATSC reception (a USA
>> > thing; I don't know if this
>> > > is the same case with other standards), a "channel" is
>> > a combination of
>> > > frequency and program ID selected within the stream.
>> > >
>> > > With analog mode, the pvrusb2 driver is more involved
>> > in the process of
>> > > setting the frequency; it receives the API request and
>> > passes that
>> > > information to the V4L tuner module.  But in
>> > digital mode, complete
>> > > control of the RF tuner section is turned over to the
>> > DVB subsystem.
>> > > Beyond providing physical I2C access to the relevant
>> > chip(s), the
>> > > pvrusb2 driver is not at all involved in channel
>> > selection there.  (The
>> > > fact that the DVB architecture means that DVB has to
>> > effectively "own"
>> > > the tuner section exclusively away from the pvrusb2
>> > driver is why we
>> > > have this wierd non-orthogonal thing going on where
>> > you have to switch
>> > > APIs when switching modes.)
>> > >
>> > >
>> > > >
>> > > > Various logs..
>> > >
>> > >   [...]
>> > >
>> > > > [   24.554160] pvrusb2: Set up
>> > standard idx=11 name=PAL-K
>> > > > [   24.554166] pvrusb2: Set up
>> > standard idx=12 name=SECAM-B
>> > > > [   24.554172] pvrusb2: Set up
>> > standard idx=13 name=SECAM-D
>> > > > [   24.554178] pvrusb2: Set up
>> > standard idx=14 name=SECAM-G
>> > > > [   24.554184] pvrusb2: Set up
>> > standard idx=15 name=SECAM-H
>> > > > [   24.554190] pvrusb2: Set up
>> > standard idx=16 name=SECAM-K
>> > > > [   24.554195] pvrusb2: Set up
>> > standard idx=17 name=SECAM-K1
>> > > > [   24.554201] pvrusb2: Set up
>> > standard idx=18 name=SECAM-L
>> > > > [   24.554207] pvrusb2: Set up
>> > standard idx=19 name=SECAM-LC
>> > > > [   24.554214] pvrusb2: Initial
>> > video standard auto-selected to PAL-B/G
>> > > > [   24.554236] pvrusb2: Device
>> > initialization completed successfully.
>> > > > [   24.554409] pvrusb2: registered
>> > device video0 [mpeg]
>> > > > [   24.554418] DVB: registering
>> > new adapter (pvrusb2-dvb)
>> > > > [   24.620865] cx25840 4-0044:
>> > firmware: requesting v4l-cx25840.fw
>> > > > [   26.944036] eth0: no IPv6
>> > routers present
>> > > > [   27.124735] cx25840 4-0044:
>> > loaded v4l-cx25840.fw firmware (16382
>> > > bytes)
>> > > > [   27.355490] usb 1-2: firmware:
>> > requesting v4l-cx2341x-enc.fw
>> > > > [   27.656232] cx25840 4-0044:
>> > 0x0000 is not a valid video input!
>> > > > [   27.706604] DVB: registering
>> > adapter 0 frontend 0 (NXP TDA10048HN
>> > > > DVB-T)...
>> > > > [   27.740746] tda18271 4-0060:
>> > creating new instance
>> > >
>> > > Up to this point, everything looks good.
>> > >
>> > >
>> > > > [   27.741738] tda18271_read_regs:
>> > ERROR: i2c_transfer returned: -5
>> > > > [   27.741751] Unknown device
>> > detected @ 4-0060, device not supported.
>> > > > [   27.741982] tda18271_read_regs:
>> > ERROR: i2c_transfer returned: -5
>> > > > [   27.741993] Unknown device
>> > detected @ 4-0060, device not supported.
>> > > > [   27.742001] tda18271_attach:
>> > error -22 on line 1243
>> > > > [   27.742011] tda18271 4-0060:
>> > destroying instance
>> > >
>> > > Here a problem has happened :-( The failed driver
>> > mentioned above is
>> > > involving in RF tuning...
>> > >
>> > > A while back (a year or more) there was some thrashing
>> > about in the
>> > > v4l-dvb subsystem involving proper tuner control for
>> > the HVR-1900.
>> > > There have been posts to the list in the past
>> > regarding I2C errors
>> > > taking place during tuner initialization, just like
>> > what you see above.
>> > > I've never been able to reproduce any of it, but part
>> > of the reason may
>> > > be that I'm in the USA and only have an HVR-1950 not
>> > the HVR-1900 you're
>> > > using.  But this was a while ago and I thought
>> > the issues behind this
>> > > were in fact in v4l-dvb (not pvrusb2) and had been
>> > solved.  That being
>> > > the case, you might be using a kernel version that is
>> > too old...
>> > >
>> > > Certainly without the ability to control the tuner on
>> > the device, that
>> > > would explain why channel switching isn't working.
>> > >
>> > >
>> > > > tomas at MythCube:~$
>> > > >
>> > >
>> >
>> -------------------------------------------------------------------------------
>> > > >
>> > > > My plan is to use it with MythTv, Ive set it up
>> > bot like a USB-device and
>> > > > like a ITVT-device without success.
>> > > > Entered my channels manually with MythWeb but
>> > only noise when changing
>> > > > channel.
>> > >
>> > > I've never had to add channels manually.  In
>> > analog mode, I've just told
>> > > MythTV which channel map to use (e.g. "US Broadcast")
>> > and for digital
>> > > mode MythTV can scan all the frequencies and pick up
>> > the channel
>> > > mappings on its own.
>> > >
>> > >
>> > > >
>> > > > Tried using VLC, but cant figure out how to set
>> > frequency, "vlc
>> > > /dev/video0"
>> > > > just brings same noise.
>> > >
>> > > If you open /dev/video0, then you're in analog mode
>> > (using V4L).  Was
>> > > that your intention?  It's still not clear to me
>> > whether you're trying
>> > > to use the device in analog or digital mode.
>> > >
>> > >
>> > > > The red lamp on the hvr-1900 lights up when Im
>> > trying to use it, so it
>> > > looks
>> > > > like everything works except changing channel, so
>> > thats why Im thinking
>> > > that
>> > > > the problem lies in pvrusb2-driver.
>> > >
>> > > The pvrusb2 driver directly controls the operation of
>> > the red LED on the
>> > > device.  In Windows, that LED lights up when the
>> > driver is loaded and
>> > > stays lit permanently.  But the pvrusb2 driver
>> > will only light the lamp
>> > > when it is streaming video.
>> > >
>> > > FYI, the pvrusb2 driver is always responsible for
>> > setting up and running
>> > > the video pipeline, regardless of mode or input.
>> > When you're in analog
>> > > mode, the pipeline is set up to use the mpeg encoder
>> > and the pvrusb2
>> > > driver "connects" the dataflow out through the V4L
>> > device spigot where
>> > > the application is running, i.e. whoever has opened
>> > /dev/video0.  If
>> > > you're in analog mode using the tuner ("television"),
>> > then the driver
>> > > connects the video digitizer to the output of the
>> > tuner.  If you're in
>> > > analog mode and capturing composite or s-video, the
>> > driver connects the
>> > > video digitizer to whichever of those inputs you've
>> > selected.  If you're
>> > > in digital mode, then the pipeline is configured to
>> > effectively bypass
>> > > mpeg encoding - since it's already digital bits - and
>> > its input is
>> > > always connected to the tuner.  The pipeline
>> > output however doesn't go
>> > > to a device endpoint; in this case the pvrusb2 driver
>> > pipes the data
>> > > directly into the DVB subsystem (where additional
>> > processing may take
>> > > place but by this point it's out of the realm of the
>> > pvrusb2 driver).
>> > >
>> > > Any time you see that red LED lit, the pvrusb2 driver
>> > has the video
>> > > pipeline configured appropriate for the mode and input
>> > and is streaming
>> > > data through it.  If you are actually getting a
>> > video stream - even if
>> > > it's snow - then A LOT of things are in fact working
>> > fine.  If the video
>> > > streaming were not working then you wouldn't get any
>> > data at all.
>> > >
>> > > Generally if you can stream video but it's always
>> > snow, then it's a
>> > > tuning problem, as you were already guessing.
>> > But to address that one
>> > > needs to look at the tuner driver and possibly also
>> > this may be affected
>> > > by whether you're in analog or digital mode (the tuner
>> > driver internally
>> > > can behave differently, depending on the driver).
>> > >
>> > > There's an easy experiment you can try to verify if
>> > this is really a
>> > > tuning problem: Try to stream the composite or s-video
>> > inputs instead.
>> > > In those cases you have to be in analog mode and you
>> > have to tell the
>> > > driver to switch inputs.  And obviously you need
>> > a video source, e.g. a
>> > > DVD player output, a VCR, camcorder, iPod composite
>> > output, whatever.
>> > > You can do the experiment without even needing a V4L
>> > app, by using the
>> > > sysfs interface in the pvrusb2 driver.
>> > Information on using sysfs can
>> > > be found here: http://www.isely.net/pvrusb2/usage.html#sysfs
>> > >
>> > > If you can successfully stream one of those inputs,
>> > then you've verified
>> > > correct operation of every part of your device except
>> > the tuner section
>> > > itself.  That being the case, the pvrusb2 driver
>> > is fine.  I'm betting
>> > > that will work for you.  To deal with the tuner,
>> > we need to understand
>> > > which kernel version you are running and if you've
>> > overlaid a v4l-dvb
>> > > snapshot (which would have a later tuner driver).
>> > >
>> > >
>> > > >
>> > > > All helps are appreciated since I've been trying
>> > for a couple of weeks
>> > > now
>> > > > google around for info...
>> > >
>> > > Let me know if any of the above helps.
>> > >
>> > >   -Mike
>> > >
>> > >
>> > > --
>> > >
>> > > Mike Isely
>> > > isely @ isely (dot) net
>> > > PGP: 03 54 43 4D 75 E5 CC 92 71 16 01 E2 B5 F5 C1 E8
>> > > _______________________________________________
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