$Id: usage.html 2476 2010-05-30 21:19:12Z isely $
Mike Isely <isely at pobox dot com>
You can find the main driver page on the web at http://www.isely.net/pvrusb2/pvrusb2.html.
This page describes how to use the driver, including module options, interface control, and information about driver-specific effects with certain apps.
Driver logging / parameters
Hotplug behavior / recovery
xine and vlc
Playing well with others
The level of log verbosity within the pvrusb2 driver is controlled through a global bit mask variable whose name is debug. This mask is set initially at compile time; you might want to change it. Set / clear bits in this mask to enable / disable various forms of logging to the kernel. The default value of this bit mask is currently fairly quiet.
The debug bit mask definitions are all contained in the driver source inside pvrusb2-debug.h. The bits are generally organized in order of increasing noise level. There are three ways to adjust these bits:
There are a number of module parameters you may specify to the pvrusb2 module when it is loaded; none however are strictly needed. Note that these parameters are also all visible at run-time by examining the directory /sys/module/pvrusb2/parameters/. Most parameters there are read-only (because they only are looked at during initialization). However as pointed out above the debug parameter in particular can be changed at any time simply by echoing a new value into its file name within that directory.
Note that unless otherwise pointed out, these parameters are global to all instances of the driver (i.e. if you have two PVR USB2 devices plugged in the effect is the same on both corresponding driver instances). The following parameters exist:
The pvrusb2 driver should be robust enough now that it can survive about any hardware abuse you can throw at it. There are no known situations where it should ever generate a kernel oops. You should be able to plug / unplug the hardware or insert / remove the driver (or just about any support module) to your devious heart's content and the Linux kernel should just keep merrily going on its way. (Obviously if you find out otherwise, please let me know.)
There is one potential issue however with the device itself. From experiments I have done, it seems that if the device is in the middle of transaction with the driver, that unplugging the device at that instant can leave it in a useless (maybe crashed?) state. The only recovery is to power cycle the device. I have tried numerous approaches to implementing automatic recovery in the driver, but there doesn't seem to be any strategy possible that guarantees recovery. However I did the next best thing: If the driver detects that the device might be jammed, it will log a message suggesting that the device be power cycled. The driver should come through all this just fine of course. (Update 4-Jan-2006: It has been a very long time since I've seen this problem repeat; it might have been something else long since fixed in the driver.)
This driver provides an implementation of the video4linux version 2 and version 1 driver APIs. Any v4l application which can handle an mpeg2 stream should in theory be able to use this driver. (Unfortunately there seem to be very few v4l apps which can...) If the v4l app you want to use does not support decoding of an mpeg2 stream from the driver, then it will definitely not work.
One application you can try is xawtv 4.x. Note that anything before version 4 will definitely not work with this since earlier versions did not support mpeg2 decoding.
Note that when you compile xawtv, make sure that you've configured it for mpeg2 video decoding and mp3 audio decoding. The app's configuration process tries to detect what libraries you have installed on your system, and if it doesn't find what it is looking for then it will silently disable parts of itself, i.e. no mpeg2 decoding. Inspect the configuration output and make sure it looks OK...
The xawtv application seems to have a number of rough edges. Best advice is to make sure you're running a recent snapshot. Some specific details:
Another application that works is mplayer. There are three ways to use mplayer: You can tell mplayer it's dealing with a V4L tv device, you just pass it /dev/video0 (or whatever the right name is on your system) as the "file" to play, or you can run mplayer in pvr mode.
The first method does not work. The second method (pass the device name as a plain file argument) however works well. The reason why you just can't tell mplayer it is talking to a V4L tv device is because once you do that then mplayer goes "dumb" and decides to only attempt streaming of uncompressed video (i.e. no mpeg2 streaming), which of course won't work since our hardware here produces mpeg2...
Unfortunately that second method also means you can't use mplayer to control the various V4L specific attributes of the device (e.g. frequency, volume, etc) since after all in this case mplayer is unaware that it is working with a V4L device. This means that when running mplayer you must do something else alongside mplayer in order to control the device. Basically we're talking about an arrangement where mplayer is showing you the output but you have to use some other method to provide control input. I test a lot with mplayer, and in my case I just use the driver's sysfs interface. But I've heard of other stories where people have used for example xawtv (3.x) in parallel with mplayer, or even an ivtv utility (e.g. ivtv-tune) to control the device. The pvrusb2 driver supports multiple opens of course so you should be able to use any other app (or just sysfs) as a control interface while mplayer is running (or before starting it).
Then there's also that third method: pvr mode. In this case you prefix the device path with "pvr://", e.g. "pvr://dev/video". Doing this causes mplayer to use the V4L API similar to that first non-working method however now an mpeg stream is expected. Thus you get the best of both worlds. In addition, when in this mode mplayer enables another option "-pvr" that gives you access to the extended mpeg encoder controls available from V4L drivers (such as pvrusb2) which use a hardware mpeg encoder (read the mplayer man page for details). This should work well with the pvrusb2 driver, though I personally have not exercised this a lot.
Several people have encountered problems reading pvrusb2 output with mplayer if the the avisynth.dll codec is installed in mplayer. This can be found in /usr/lib/win32/avisynth.dll. I can't profess to know what that codec might provide (or even if it is a codec) since I don't use it. However for those who have encountered problems in mplayer with this driver, removing this codec solves the problem.
One issue I've seen with mplayer: It sometimes poorly handles things when the mpeg2 stream is temporarily disrupted. A disruption can happen if for example you change the channel, or if the RF signal is lost. This seems to confuse mplayer in such a way as to cause the audio and video to get out of sync. If the "gap" is small enough then mplayer seems able to bring things back into sync within a few seconds. But the larger the gap, the less likely it is that it will recover. How do I know this is mplayer and not the driver? Because if I instead cat the video stream into a file, introduce a gap there, and then later play that file with mplayer, then it works fine. It seems that mplayer is sensitive to real-time pauses in the video, and since playing back the recorded file means there is effectively no real-time pause, then it's fine. I can make this issue happen using both 24xxx and 29xxx devices, but it seems more likely to be a problem with 29xxx devices. This might be because 29xxx devices might simply be a little slower in reacquiring video sync after a channel change (the digitizer chip is different between the two).
Similar to mplayer, xine and vlc are reported to work provided you treat the device file as just a normal file with mpeg contents. There is a v4l mode apparently for xine (I haven't tried it), but I've heard that it is very immature and definitely does not work with this driver when run in that manner. I've been told that these example invocations should work:
xine - < /dev/video vlc - < /dev/video
For vlc, I've heard later reports where the above didn't work. I'm really not a vlc expert, but I've also seen this work:
vlc stream:///video/video0 cat /dev/video0 | vlc stream:///dev/stdin
It is possible to get Kaffeine to work with this driver (streaming only?) using the following MRL:
This is a relatively new application - built with Tcl/Tk - designed to provide a simple means to just watch and record TV programs. The author, Christian Rapp, has using the pvrusb2 driver as one of his test targets so it should play quite well with the driver. This project was recently moved to sourceforge: http://tv-viewer.sourceforge.net
I've also periodically used this project as another means to test the driver. Anyone considering xawtv should probably give this a try as well.
The MythTV application of course is the holy grail for this driver. I got sucked into this whole effort because of this desire. This driver is known to work well in MythTV.
If you want to try MythTV, here are some tips:
The MythTV wiki has a nice page (http://www.mythtv.org/wiki/Hauppauge_WinTV-PVR-USB2) about using the pvrusb2 driver. The page's author (I didn't write it) apparently put it together from his own experiences with the device in combination with the driver and the notes you see from the various parts from the pvrusb2 web site here. The additional perspective provided by that article might provide further clarity on the subject.
MythTV is of course also a DVB application. It should work fine with the DVB interface provided by the pvrusb2 driver, when operating the digital side of a hybrid device. You should be able to specify both the V4L and DVB interfaces to MythTV, which would then allow you to fully utilize the hardware.
Note that in the case of hybrid devices supported by this driver with DVB, only one interface (V4L or DVB) can be opened / streamed at a time. After all, there's really only one tuner here - it just operates in two modes. It is possible under certain conditions that MythTV may erroneously try to open both interfaces at the same time, which of course fails and you don't get a recording. When you first configure MythTV there is a way to relate the two interfaces so that MythTV won't collide with itself. However even when you do this, it still won't stop a collision if you have EPG enabled on the digital side. The term "EPG" refers to the Electronic Program Guide, which is a means where MythTV can get upcoming program information from the station(s) themselves. However if you do this then MythTV opens the DVB interface and listens for that information, without regard to whether or not it wants to use the analog side, thus the analog side gets locked out and you get errors. So, cutting to the chase, you probably do not want to enable EPG when you use this driver (unless of course you don't ever use the analog side or maybe you have two devices and want to dedicate one to just EPG retrieval and digital recording).
I think one of the best v4l TV apps out there is tvtime. It's got a clean and simple interface, yet is very powerful and just produces a wonderful video image.
Unfortunately tvtime does not support mpeg2 decoding and thus has no chance of working with the pvrusb2 driver.
Realize that this isn't so much a deficiency of tvtime as it is a result of its overall architecture. The tvtime app is designed to work directly with uncompressed video frames from a capture device. As such, it relies on the capture device for video frame timing, and hardly has to bother with audio (since for an analog capture card the audio is usually directly shunted to the line-in of your sound card). To support mpeg2, tvtime not only must decode the frames, but it must also generate its own timing. It must also deal with audio decoding and therefore also implement its own communications pathway into your sound subsystem. And it must do all that while keeping the audio and video in sync. None of that is impossible, but I have been told that it pretty much completely contradicts the internal architecture of tvtime. It seems doubtful that tvtime will ever support a v4l device which speaks mpeg2. It'd be great if it did handle mpeg2 - that nice interface is something I dearly miss. But I'm not holding my breath for it to happen.
Please contact me if you find other apps which work, and I'll list them here.
This v4l implementation should allow for multiple opens. Said another way, if you have one application reading video from /dev/video0, it should be possible to have another application still open /dev/video0 and successfully manipulate driver controls. Of course, only one application at a time can stream video. A second attempt at streaming will be greeted with an I/O error.
The pvrusb2 driver exports a limited DVB interface. This will be created if the device being handled is a hybrid (i.e. has a digital tuner). Right now the only means to access the digital side is through the DVB interface. Similarly the DVB interface does not operate the analog side, which is why this interface is currently only made available for hybrid devices.
I have not yet gained a lot of experience in playing with DVB apps, however the DVB interface is well defined so I would expect about any DVB supporting app to be able to operate the digital side of pvrusb2-supported hybrid tuners through this interface.
MythTV is a well known app that uses DVB. This driver should work with it. For more information, see the MythTV description here.
In the long term I would like very much to put the V4L and DVB interfaces on an equal footing. It would be a lot simpler conceptually if all features were equally available through both interfaces. The fact that the hardware mpeg encoder can make the analog side "look" like a digital stream should in theory make DVB operation of the analog not impossible. But right now this is not the case, and thus the DVB side is limited to digital tuning and the V4L side is limited to analog tuning.
There is an additional interface available with this driver. In parallel with the v4l interface, you can access all driver controls via sysfs. Once the device is plugged in and the driver is loaded, try this:
# cd /sys/class/pvrusb2/sn-XXXXXXX
where XXXXXXX is the serial number of your device (just let tab-completion do the hard work here or use "*" since unless you have multiple tuners there will only be one file there anyway). Now use "ls" and you'll see a whole bunch of directories all starting with "ctl_". Here is what my system looks like:
londo:~# cd /sys/class/pvrusb2/sn-6829718/ londo:/sys/class/pvrusb2/sn-6829718# ls bus_info_str ctl_video_b_frames ctl_audio_bitrate ctl_video_bitrate ctl_audio_crc ctl_video_bitrate_mode ctl_audio_emphasis ctl_video_bitrate_peak ctl_audio_layer ctl_video_chroma_median_filter_bottom ctl_audio_mode ctl_video_chroma_median_filter_top ctl_audio_modes_present ctl_video_chroma_spatial_filter_type ctl_balance ctl_video_gop_closure ctl_bass ctl_video_gop_size ctl_brightness ctl_video_luma_median_filter_bottom ctl_channel ctl_video_luma_median_filter_top ctl_contrast ctl_video_luma_spatial_filter_type ctl_freq_table_channel ctl_video_median_filter_type ctl_freq_table_value ctl_video_spatial_filter ctl_frequency ctl_video_spatial_filter_mode ctl_hue ctl_video_standard ctl_input ctl_video_standard_mask_active ctl_master_state ctl_video_standard_mask_available ctl_mpeg_audio_mode ctl_video_temporal_decimation ctl_mpeg_audio_mode_extension ctl_video_temporal_filter ctl_mute ctl_video_temporal_filter_mode ctl_resolution_hor ctl_volume ctl_resolution_ver debugcmd ctl_saturation debuginfo ctl_signal_present device ctl_srate power ctl_streaming_enabled subsystem ctl_stream_type uevent ctl_treble unit_number ctl_usb_speed v4l_minor_number ctl_video_aspect v4l_radio_minor_number londo:/sys/class/pvrusb2/sn-6829718#
(The device and driver links you see there by the way are standard things which point off to other parts of sysfs where the driver's and device's lower level control files can be found. There are also other bits and pieces showing here that help with debugging the driver or learning things about how it is set up.)
Note: As said above, the "XXXXXXX" part of the path is the device's serial number. It is possible that the driver might not be able to retrieve a serial number from the device (if there were problems reading the device's PROM). In this situation, the sysfs implementation here will substitute the device's unit id using the form "unit-X" (instead of "sn-XXXXXXX") where "X" is the letter for the unit assigned to the device instance.
Each ctl_ directory has some subset of these files:
You can read any of these files just by cat'ing it out. All are read-only except for cur_val and custom_val, most of which can be set by just writing the new value into it (a few of those controls are actually completely read-only). The incoming value must be either an integer within the legal range specified by min_val and max_val, a legal enumeration constant (for enumerated controls), a true / false or yes / no literal (for boolean controls), or a bit mask assignment (for bit mask controls) in order for the assignment to "take". Otherwise the program doing the write should get back an EINVAL or ERANGE error status.
Bit mask controls have a somewhat more complex expected format in order to support the setting and clearing of individual bits within the mask. The values you write in are expected to be a set of whitespace-seprated bit names. If just the names are used then the entire mask is set to just those bits. If however each bit name is prefixed with a "+" or a "-", then just those corresponding bits will be set or cleared (respectively) without affecting the other bits in the mask.
The contents of the custom_val file is determined entirely by the specific control itself; there is no defined format unlike with cur_val. This will only appear if the control has a way to format its own value. Currently it is only used to show video standard mask values, where this custom form adheres closer to normal conventions for expressing multiple standards. If the control in question is writable, then this may be writable as well (in which case the control will parse the symbolic value itself to determine the desired underlying internal value). If none of this makes sense to you, then you can just safely ignore the existence of the custom_val file.
I initially put together this interface to make it easier to debug the driver, independent of an application like xawtv (in fact, see dbgifc.html for further info on debug aspects of this interface). But the possibilities here are obvious. For example, it is possible open the /dev/ entry into mplayer and then completely control everything else with this sysfs interface while mplayer is running. (I routinely test the driver this way.) One could write a shell script control program with this interface...
Please be aware that with this interface one has complete run of all the driver's controls. There are certainly combinations of settings which, uh, won't work very well. But as I said, I had initially put this here to make it easier to debug the driver. It was either this or invent a pile of new ioctl()'s and write a test program to operate those settings (the ioctl() approach is what ivtv does).
In the driver source tree, there is a file doc/controls.txt which annotates each of the controls with information about what it is expected to do, what effects may or may not happen, and whether certain settings work or not. I put this together after experimentation with the device. Others may find it handy so I've made the results available.
The IR receiver within the model 29xxx series devices is an I2C part that is already understood by the lircd software package (0.7 or later). A long long time ago Aurelien's driver hardcoded something here which made the IR receiver into another source for /dev/input, but I had stability problems with this and just decided to rip it out in favor of letting more stable external software handle this function.
The IR receiver within the early model 24xxx series devices is some glue logic and firmware within the FX2 microcontroller that is operating the device. There's no actual I2C interface and thus no way for any external chip-level driver to reach into the pvrusb2 driver and operate the part. The pvrusb2 driver handles this situation by operating this feature itself and presenting the results as an emulation of the I2C chip that would otherwise be present in 29xxx devices. Thus, even though those early 24xxx devices don't actually have the expected chip, everything still works properly and outside logic (e.g. lirc) still thinks it is talking to a normal Hauppauge I2C-based IR receiver.
Later 24xxx models (the "MCE" version) included an IR blaster, and with that change the IR landscape there changes again. In that case the IR receiver is an I2C device again but its interface is alien to what had been used in the 29xxx models. The pvrusb2 driver makes no attempt to emulate anything here and just stays out of the way. However lirc should still be able to work with this device (just a different low level driver is inserted, try the one used for the "PVR-150").
The HVR-1950 / HVR-1900 models contain an IR receiver / blaster that I believe resembles that from the later 24xxx models and in theory should also work with lirc in the same manner. However I have not heard any reports of success there yet (if somebody gets this to work, tell me)...
It appears that onair hardware has an IR receiver, but I do not know if it is usable.
Generally, making IR reception work is mostly just a case of install lircd and go (see important note at the end of this section about ir-kbd-i2c). It's the same thing you would do to get IR working in ivtv. In other words, grab lirc, build it, modprobe the appropriate driver into the kernel and when configured with the correct lircd.conf (one appropriate for the PVR USB2's included remote is provided with the standalone pvrusb2 driver), it will "just work". The I2C driver will discover the internal I2C bus made available by the pvrusb2 driver, probe that bus, and attach itself when it finds the IR receiver chip it will be looking for. For later devices (e.g. HVR-1950) you will likely need a much more recent version of lirc.
Note that if you are a Debian user, there is an lirc-modules-source package which you can in theory just install and build against your kernel tree. I and others have found that package to be broken. It won't compile cleanly. (See here for the current situation with this package.) You're probably better off just using the vanilla version from the lirc web site.
There is a second but limited way to make IR work with the pvrusb2 driver, if you dislike lirc and would prefer something which works with a /dev/input style interface. Included as part of the V4L core is the module ir-kbd-i2c.ko. If you insert that module into your kernel, then it will drive the I2C chip and present the results via /dev/input. This is true for kernels up to 2.6.29. Note: This only works for 29xxx and earlier non-MCE 24xxx devices; for other devices the IR hardware is too different to be handled by ir-kbd-i2c.
For kernels 2.6.30 or later things are messier at the moment. The I2C internal infrastructure changes such that now the pvrusb2 driver must explicitly issue a call that binds clients like ir-kbd-i2c into its I2C bus. Thus, just modprobe'ing ir-kbd-i2c won't work without help. In fact, it's entirely likely that lirc won't work either until / unless some changes are made there. Right now I'm not very clear on this. However to support ir-kbd-i2c, the pvrusb2 will try to autoload it where appropriate, regardless of kernel version. This means that if you are using lirc, then there may be some interference from ir-kbd-i2c. When I say "appropriate" what I mean is that the attempt will only be made if the device in question has an IR receiver that is known specifically to work with ir-kbd-i2c (e.g. currently only 29xxx and early 24xxx models). In an attempt to still allow lirc to work (if it will work at all), there's a module option available. Specifiy "disable_autoload_ir_video=1" and the pvrusb2 driver's autoloading of ir-kbd-i2c will be suppressed.
As of the 20061227 snapshot, the pvrusb2 driver supports operation
of the FM tuner where possible in the hardware. Many thanks go to
That is trivially done through sysfs, but it can also be easily done through the normal V4L api as well. Once in radio mode, just stream data as you normally would. The result is still an mpeg stream; video will be blank and the audio will be the radio station you have tuned. Other things to be aware of:
Getting a full mpeg stream with (blanked) video embedded is kind of wasteful. Usually you really only want the more familiar mp3 audio stream packaged within that full mpeg stream. The driver doesn't (currently) do anything to process the mpeg stream; it only passes on what it gets from the hardware and right now all that we can do in the hardware is spit out mpeg. But there's no reason why you can post-process the data in a user process. You can use the app mpeg2desc to filter for the audio stream. For example:
cat /dev/video0 | mpeg2desc -a0 >/tmp/audio_data.mp3
To get regular old pcm, go one step further, with the help of mpg123:
cat /dev/video0 | mpeg2desc -a0 | mpg123 >/tmp/audio_data.wav
The mpeg2desc program can be usually found as a tool within the dvdauthor package, and mpg123 (or mpg321) is usually available in various distros. Credit again to Pantelis Koukousoulas for suggesting this.
A somewhat less clever variation of the above is also possible with a single invocation mplayer:
mplayer -vo null -ao pcm:file=/tmp/audio_data.wav /dev/video0
That last trick is actually useful for getting digital audio out of just about any stream format - if mplayer has a codec for it, then you extract out the digital audio from it.
There is a frequency table implemented inside this driver. It is not available for v4l, but it can be used with the sysfs control interface. You must program it first before using it, but once programmed it becomes possible to change the channel just by, well, writing the new channel number to the driver. The table size is currently limited to channel numbers 1 through 500 (far in excess of anything anyone should need), and the channel ids must be integers not something cute like station call letters.
Note: You do not need to program this frequency table or otherwise even touch it when using this driver with any v4l application. This table is not even visible in the v4l API; it is only present here to make it easier to debug the driver using sysfs.
The frequency table must be programmed a slot at a time. You do this by first selecting the slot's id (a.k.a. the channel number) into the freq_table_channel variable through sysfs. Once selected, you can read / write the frequency (in Hz) for that slot using the freq_table_value variable through sysfs. Repeat this process for all channels to be programmed. Yes, this is just begging for a shell script to do the dirty work. Thanks to Per Christian Henden, one example of such a script exists now in the utils subdirectory (see utils.html for more information about this).
Once you've programmed the desired slots in the table, just "change the channel" by writing the desired channel number to the channel variable through sysfs. That's it.
The frequency can still be set as before by writing the actual frequency to the frequency variable. If that is done, then the channel will be implicitly set to zero, which means "none". Thus the channel and frequency variables at all times stay consistent with each other and there's no loss of flexibility or any implied confusion.
The frequency variable can of course be read back at any time to see what the actual frequency is, regardless of whether it was set directly or implied by a channel setting. And of course the channel variable can be read back at any time to find out what the current channel is or if it is not being used due to the frequency being directly set (in which case the value read back will be zero).
Why do this? Well it was dirt-cheap easy to implement, and it does help with debugging, though in a minor way. Besides it's cool to do. OK, OK. Enough playing and back to the real rework...
The following is a summary of issues / tips when using this driver alongside other software or in less-typical environments.
Even though the PVR USB2 hardware is a USB device while everything else driven by ivtv is a PCI device, there really is more than a passing resemblance among them. As such it's no coincidence that both happen to share the same chip-level drivers. This is in fact where the chip-level drivers in the ivtv subdirectory of the standalone driver snapshot came from. Even the same cx23416 mpeg2 encoder - which is the heart of ivtv - is also used in the PVR USB2 device. If you have / need to also use ivtv, it should be possible for this driver to coexist with it. Any ivtv-provided chip-level drivers should also work fine with the PVR USB2 driver, thus the two drivers should be able to coexist nicely on the same system.
The X-box has an internal I2C bus, and the code that was hacked together for it makes the assumption that it is the only I2C bus that can possibly exist on an xbox. That assumption becomes false when a PVR USB2 device is introduced, unfortunately. The problem here is that the I2C driver code for the xbox tries to attach to the PVR USB2's I2C bus, causing dangling pointers in the xbox driver code and chaos ensues. If you have an xbox, I have a patch for the xbox I2C driver code that makes it play nicer (it's still a horrible hack though). Contact me for the patch.
The v4l system in Linux is undergoing rapid development. This can cause issues for an out-of-tree driver like the pvrusb2 driver. The standalone version of the pvrusb2 driver goes to some length to detect and interoperate correctly with whatever surrounding v4l environment it finds itself operating inside of, however it can be hard to keep up. The in-V4L version of the pvrusb2 driver is less complex in this area since it can always assume exactly what v4l environment in which it is running. If you find you are having problems with the pvrusb2 standalone driver and you suspect v4l incompatibilities as the cause, then contact me or check the mailing list for chatter about such a problem. And of course you can elect to simply update to the latest v4l repository snapshot, with its included in-V4L version of the pvrusb2 driver.
Hybrid devices are handled in the pvrusb2 driver with both V4L and DVB interfaces. Internally it's all one driver under unified control, but externally the two interfaces make it look like two drivers. So what interactions can happen between the interfaces?
Digital tuning in the pvrusb2 driver is implemented as logically another input choice. Thus if you use sysfs to enumerate the choices for ctl_input you'll also see a "dtv" choice for the digital tuner.
In theory the V4L side can simply select the "dtv" input and stream digital TV. However the current architecture of the V4L/DVB subsystem makes this impossible, due to the fact that digital tuning is tightly entangled with the DVB subsystem. The only way to perform digital tuning at the moment is through DVB, simple as that. There are some ideas to solve this, but it's still a work in progress.
The DVB interface currently has no ability to select an input choice. This causes an issue in the pvrusb2 driver since the "dtv" input choice must be selected in order to perform digital streaming.
The above two issues led to implementation of a special feature in the pvrusb2 driver, both to prevent inoperable hardware configurations from being run and to keep V4L and DVB from stepping on each other. The feature is known as "narrowing". It works like this: When a given interface is opened, the list of legal input selections in the driver is automatically narrowed to that which is usable for the open interface. Thus when a V4L app opens the V4L interface, the "dtv" choice is dropped from the list of inputs - and when a DVB app opens the DVB interface, every choice except the "dtv" choice is dropped from the list of inputs.
If the current input selection is no longer valid after the narrowing step, the driver immediately switches to one of the remaining choices.
The effect of the narrowing operation is canceled when the interface that caused the narrowing is closed.
If the set of remaining valid input choices becomes empty, then it is a disallowed narrowing operation and the interface which caused it will get back an error. This prevents simultaneous opening of the V4L and DVB interfaces - the second one to open will be denied with an error because the other interface has already narrowed-away the desired input choice(s).
Along a similar line of reasoning, the V4L radio device behaves in a similar manner. If the radio device is opened, then the set of input choices is narrowed to be only the radio - therefore the radio become active when the V4L radio interface is opened.
You can observe this behavior through the sysfs interface - dump the enumerated list of input selections under various conditions and note how the list changes depending on what interface is open.
All of the above is long-winded way of saying the the pvrusb2 driver currently enforces mutual exclusion between the V4L and DVB interfaces - when one is open, the other will be denied. Any app wanting to use both interfaces (e.g. MythTV) must be aware of this.