[linux-dvb] OnAir USB HDTV Creator experiences?

Michael Krufky mkrufky at linuxtv.org
Wed Jan 3 05:30:30 CET 2007


A. F. Cano wrote:
> I have found that some code was added to support the OnAir Creator here:
> 
> http://linuxtv.org/hg/~mkrufky/onair?cmd=changeset;node=4196304d0395;style=gitweb
> 
> but nowhere else did I see any indication that this unit works at all
> with Linux.  So my question, before I go ahead and buy an expensive
> paperweight: Has anyone tested this patch? What kind of functionality
> is possible under (Debian) Linux?  Experiences with specific
> applications?  What percentage of the features of this unit have been
> tested and found to work? As it does have an analog tuner (and analog
> capture via standard video input), how does one use this unit under
> Linux?  Is it a matter of using a patchwork of a dozen or so
> applications to get the full functionality?  ie: one app for channel
> scan, another to change channels, another couple to view the digital/
> analog streams, another to record to HD, another to time-shift, etc...
> Has anyone tested it with, say, MythTV?

A.F. Cano,

Thank you for expressing your interest in the experimental linux driver
for the OnAir USB HDTV Creator.

> Has anyone tested this patch?

I am the developer of this driver -- I have tested it, and Mike Isely
(cc added) has also tested it.  The HDTV driver is working properly, 
except for one bug.  This bug is extremely annoying, and I consider it
to be a showstopper -- this is the reason why I have not yet merged this
code into the master v4l-dvb development repository.

The bug:  The device never has any problem tuning or getting a lock.
However, the driver is rarely able to return a transport stream over
the usb bus on the first try.  I usually have to power-cycle the device
three of four times before I can successfully receive an mpeg stream.

The windows driver does not have this problem, and I have not yet been 
able to figure out what is causing this problem in the Linux driver.

I have taken a break from troubleshooting this bug, in hopes that when
I resume my attempts to fix it, that I will look at the problem with
fresh new eyes.  If anybody else is able to fix it, I would gladly
accept patches against my onair tree.

> What kind of functionality is possible under (Debian) Linux?

The changeset that you pointed to above is a change to the cxusb driver
(dvb-usb-cxusb) ...  This driver currently allows digital-only
functionality, and it works very well with the OnAir HDTV Creator
(except for that damned bug).

OTOH, An altered version of the pvrusb2 driver can support the analog
mpeg encoder functionality of the device.  I don't have the snapshot
around anymore, but the last time I tried it the video encoding was
working very well.  We haven't yet gotten around to making the audio
work, by handling the cs53l32a... but it should be relatively simple.

> Experiences with specific applications?

As the digital capabilities of this device are supported by a DVB driver,
any ATSC/DVB application will work with it.

As the analog mpeg encoder capabilities of this device can be supported
by the pvrusb2 driver, the device can work with any v4l2 application that
can handle mpeg streams.  In addition, when using the device with the
pvrusb2 driver, it will work with any application that is able to take
advantage of the pvrusb2's sysfs interface.

> What percentage of the features of this unit have been
> tested and found to work?

I think I pretty much explained that, above.

> As it does have an analog tuner (and analog
> capture via standard video input), how does one use this unit under
> Linux?

As the support is currently being developed, there are two separate drivers
to support each functionality of this device.  dvb-usb-cxusb.ko for the 
digital side, and pvrusb2.ko for the analog side. This is only a temporary
situation while the driver is being worked on. Mike Isely is working on the
pvrusb2 driver, and I have been working on the cxusb driver.  Once
everything is working properly in separate drivers, then we'll work on
merging them into a single hybrid v4l/dvb driver.

I'll discuss the driver in further detail, below.

> Is it a matter of using a patchwork of a dozen or so
> applications to get the full functionality?  ie: one app for channel
> scan, another to change channels, another couple to view the digital/
> analog streams, another to record to HD, another to time-shift, etc...

Once the driver is complete, the device will work like any other v4l2 /
dvb device works in linux.

However, since it is being developed as two separate drivers, only analog
or digital mode can be used while the respective module is loaded. The
module will have to be manually unloaded / loaded to switch from
analog / digital modes until the functionality is merged into a single
driver.

> Has anyone tested it with, say, MythTV?

Due to the power cycle bug, I have not yet had reason to try this with
MythTV. However, the standard pvrusb2 and cxusb devices that are currently
supported in the kernel are known to work properly with mythtv (with the
exception of some tuning problems for users with the samsung dnos104z
tuners)

--- more about the driver:

The public version of the pvrusb2 driver does not yet have support for
this device -- since audio doesn't yet work in mpeg encoder mode, it
doesnt make sense to include the mpeg encoder support for the OnAir
HDTV Creator to the pvrusb2 driver...  yet.

The hardware inside the OnAir HDTV Creator is almost identical to the
hardware used in the pvrusb2 (except for the tuner / atsc demod)... 
Coincidentally, the devices supported by the cxusb driver also have
the same basic hardware design (if not, very similar). For the most part,
the firmware control API is the same for them all.

In summary, we are working to eventually have a unified driver to properly
support this device, but it is not yet ready.

Cheers,

Michael Krufky



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