[linux-dvb] networked digital tuner project
bkuschak at yahoo.com
Mon Jun 13 20:03:02 CEST 2005
> So what happens when a client crashes or the
> connection between the client
> and the device is lost? ;-) Ok, your semaphore might
> expire, but the tuner
> may be left in an undefined state...
When a new client acquires control of the tuner, the
first step is to initialize it, and tune to the new RF
channel. As such it doesn't matter what state it was
> And how is one client supposed to know what state a
> tuner is in anyway,
> when the device doesn't know itself...? Or are
> clients supposed to send out
> broadcast messages before/after reconfiguring a
> tuner so that the other
> clients know about the change as well? What if a
> client is started after a
> tuner configuration, is it supposed to send a
> broadcast message asking the
> other clients what the current tuner configuration
Your point about monitoring the other client's control
messages is valid. We probably don't want or need to
> 1) Design a _proper_ network tuner device which
> encapsulates/abstracts the actual hardware, and
> handles access control, and
> spend the time it takes to develop that.
What kind of interface would you like to see?
Something like the API provided by the linux-dvb, only
available over ethernet instead of an ioctl?
> 2) Design a "quick&dirty" network tuner device and
> spend just as much time
> implementing all kinds of workarounds (aka "hacks")
> in your client software
> to make it _somewhat_ work, but never quite as
> reliable as choice 1) would
> allow you.
Setting aside the issue of mutual exclusion between
multiple clients contending for a given tuner, there
is still value and utility in having (multiple)
networked tuners with a simple API. Several of the
applications that I had in mind (multichannel
enhanced-PVR, lookahead channel tuning, multiple-PIP,
expanability) do not strictly require these access
I'd like to see development happen in two stages. The
first would be a simple device with FPGA only. This
would provide a significant amount of functionality
with a reasonably short developement cycle. A second
stage could be the integration of a full CPU/OS and
fully abstracted tuner API. Much, if not all, of the
FPGA code developed for the first phase is directly
applicable to the second, so the effort isn't wasted.
> Why do you think you will not be able to embed the
> frontend drivers from
> the LinuxTV project into your network tuner device's
I never said that. Of course this is possible.
Running linux on one of the many ARM-based SoC out
there would allow you to provide not just the tuner
API, but also IP-decapsulation, http configuration
pages, and other things. But at that point you're
designing a full media receiver, which is a larger
scope than what I had in mind originally.
Have fun online with music videos, cool games, IM and more. Check it out!
More information about the linux-dvb