Hello kernel-space friends,
On Wed, 09 Nov 2011 17:01:59 -0200, Mauro Carvalho Chehab <[email protected]> wrote: > As I've commented with some at the KS, I started writing a new DVB > library, based on DVBv5. > It is currently at very early stages. Help and suggestions are welcome. > > It is at: > http://git.linuxtv.org/mchehab/experimental-v4l-utils.git/shortlog/refs/heads/dvb-utils > > It currently doesn't do much, but the hole idea is to offer a library that > can easily upgraded to support new standards, and based on DVBv5. IMHO, adding new standards with DVBv5 is already fairly easy, as opposed to with DVBv3. The only issue I've had (while porting VLC to DVBv5) lied in determining which parameters needed to be set and what values they would accept. (...) > The frontend library is inside: > dvb-fe.c > dvb-fe.h > > And the pertinent parameters needed by each delivery system is provided > into a separate header: > dvb-v5-std.h As a documentation, it's nice to have. It should also enumerate the legal values, a bit like V4L2 user controls. However, I'm not sure how useful it can really be used to abstract away tuning standards. There are a number of problems remaining: 1) User-space may need localization of parameters names and enumeration value names. For frequency, we also need a unit, since it depends on the delivery system. In VLC, we have to replicate and keep the list of well-known V4L2 controls parameters just so gettext sees them. The same problem would affect DVB if you carry on with this. And unfortunately, even if v4l-utils had its own gettext domain, I doubt it would get as good visibility among translators as end-user applications have (e.g. VLC has 78 locales as of today). 2) Some user-space are cross-platform, say across Linux DVB and Windows BDA. Since Windows BDA does not abstract delivery subsystems, such software cannot leverage dvb-v5-std.h. 3) Some settings are absolutely required (e.g. frequency), some may be required depending on hardware and/or driver, some are not normally required to tune. When writing a UI, you need to know that. 4) Systems like DVB-H (R.I.P.) or ATSC-M/H cannot be abstracted meaningfully as they don't provide a TS feed, so the user-space can't use them. 5) Unless/Until the library implements scanning and some kind of channel or transponder abstraction (e.g. unique ID per transponder), it is dubious that it can really abstract new delivery systems. I mean, the tuning parameters need to come from somewhere, so the application will have to know about the delivery systems. So hmm, that's a lot of problems before I could use that library. Maybe some other user-space guys are less demanding bitches though :-) -- Rémi Denis-Courmont http://www.remlab.net/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
