[linux-dvb] Re: FF cards alter PTS'?

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Holger Waechtler wrote:
> 
> Klaus Schmidinger wrote:
> > Holger Waechtler wrote:
> >>Klaus Schmidinger wrote:
> >>>
> >>>Well, AFAICS this "old hardware" is very widely used, and the main
> >>>platform VDR is designed for. And judging from the download volume
> >>>every new version of the "linvdr" distribution causes (according to
> >>>Mirko Dölle) VDR must be rather popular ;-) So I guess this hardware
> >>>will still be in use for quite a while, and I can see no adequate
> >>>replacement around - but that may be due to my lack of market
> >>>overview...
> >>
> >>:) sorry Klaus, there are plenty: Take any of the decoderless
> >>Nova/Nova-USB/ Skystar2/Avermedia cards, they cost only a fraction of
> >>the old av7110 based cards.
> >
> >
> > I wasn't referring to budget cards. I meant a full-featured card, with
> > TV-out, that is able to receive AND replay. Plus the ability to connect
> > a CAM to it.
> 
> You can buy several Budget-alike cards with CAM connector.
> 
> Yes, for some of them the CAM is not yet supported, but as long people
> only get the response get told that they need to buy an expensive
> full-featured for CAMs this won't change near future.

Looks like the typical "chicken & egg" problem.
People won't buy such cards unless they definitely know that
they are supported by the driver.

> >>And every modern PC is able to decoder
> >>several MPEG streams in software at a time.
> >
> >
> > But that would require quite a bit more CPU power than my current 450MHz
> > machine - which means more cooling, more noise...
> 
> Are you really sure? A friend of mine watches regulary MPEG2 movies
> recorded with a remotely controlled OSD-less VDR using a Nova card in
> his server on his stone-old 400MHz G3 PowerBook (no SSE, no MMX, no
> Altivec -- it's one of the old black ones with the upside-down apple
> logo, do you remember them?). The cooling fan is switched off almost all
> the time.
> 
> He also wrote a DirectFB demo application that plays back a similiar TS
> on a 500MHz Sony Vaio with a Neomagic graphics chipset without framedrops.
> 
> Well, you have to carefully enable all optimization when compiling your
> decoder library, but it's definitely possible.
> 
> Modern fanless Mainboards like the VIA Epia boards in the Hush-box have
> much more CPU power and also some MPEG decoder helper functionality
> speeding up the DCT on the CPU die (or was it on the graphics chip?).
> MythTV has some experimental support for this feature IIRC.

Well, as I always keep saying: just go ahead and write a plugin that
implements an alternate output device, and you won't have to use a full
featured DVB card any more. I get the feeling that you expect ME to do this,
but as long as my full featured DVB-S cards work as good as they do, I
don't see the need for this. I'll rather spend my time on implementing
general new features into VDR.

> >>Painting OSD bitmaps on the
> >>YUV overlay is trivial and gives you the freedom to remove all the evil
> >>hardcoded OSD-related limitations introduced in the VDR source.
> >
> >
> > The actual device implementation (including the OSD) in VDR can be replaced
> > through a plugin, like, for instance, the Xine plugin.
> > So anybody who really wants to use a different hardware for replay
> > can do so.
> 
> Nobody will do so as long everybody gets told he needs a DXR3 or av711x
> based card for VDR, not?

So what about the Xine plugin?

> >>I slowly get the feeling that VDR is might be the only reason that keeps
> >>those old expensive and misdesigned av711x cards alive, not?
> >
> >
> > If by "keeping alive" you mean "keeping them on the market", I don't
> > know. Maybe this is actually true, but then again, where's the
> > problem? If some manufacturer would sell a better DVB-S card (but
> > of course _with_ MPEG decoder and tv out) I'd gladly give it a try,
> > provided the LinuxDVB driver supports it.
> 
> Placing such a limited MPEG2 decoder on PCI cards was a dead-end, guess
> why no other hardware designer did this ever again. And they are
> expensive, guess why other cards can be so cheap.
> 
> I hope no vendor will ever do this again, today all modern processors
> are powerful enough to decode the stream in software and you still have
> plenty of free CPU time to do something else.

As you may well remember, at the time I started developing VDR, the full
featured Siemens DVB-S cards were pretty much all there was (maybe there
actually were alternatives back then, but since the initial LinuxDVB
driver mainly supported these cards, I doubt that). So I've built VDR
upon that hardware, and of course intend to keep on using it, as I've
invested some money into it and it works fine for me. Those who don't
want to do so already have alternatives, as for instance the DXR3 (which,
though, has even more limited OSD capabilities than the TT cards). And you can
always write a cDevice derived class that implements a completely different
kind of output device. But if somebody asks me today what hardware would
be best to use with VDR, I'd still recommend a full featured DVB card,
because I just don't see any reasonable alternatives.

> >>Believe it or not, VDR became a market-driving force with time, all
> >>these articles in the local computer magazines have been a source of
> >>publicity that commercial DVB card manufacturers could only dream of.
> >
> >
> > Well, apparently VDR actually does what most people really like ;-)
> > It is simple, not bloated and easy to handle.
> 
> Even worse that VDR requires those expensive cards.

I keep repeating myself: show me a cheaper (and better) alternative with
TV out and OSD, and I'll give it a try.

> >>Don't you want to add a software decoder based e.g. on ffmpeg to VDR?
> >>Take a look in the ffplay.c source code, you can rip out most of the
> >>code there. And you get HDTV and MPEG4 decoder support for free.
> >
> >
> > Personally I don't have any need for this, because I still use the TT
> > DVB-S cards, and since I have quite a few of these I guess I'll be able
> > to run them for quite a while ;-)
> 
> *g*
> Then please tell all VDR users that they shall never again complain
> about firmware issues :)

Release the firmware to the general public, then you can make such statements!

> > Well, somebody should write a plugin that implements such a device, and
> > you could run VDR without a full featured DVB card. The question would
> > then be, however, if the budget cards you use then will support CAMs.
> 
> There are also new VDR users every day still doing something stupid like
> buying av711x based cards. Just because they don't have a real
> alternative and get told to do so.

Now you say it yourself: "they don't have a real alternative".
If somebody wants to build a VDR on top of an existing (older) PC,
and wants to buy just one PCI card (maybe the PC just has one free
slot), what should he/she do in your opinion? The easiest way to
go is to use a full featured DVB card. If you want to make people
use budget cards and do the output via the graphics card, just go
ahead and write a plugin that does so.

> It's easy to tell a bloody beginner the lie that he needs a hardware
> MPEG decoder to get things going...

I don't appreciate being called a liar.

> > Please understand, though, that people aren't just going to throw
> > away their full featured DVB cards. There are hundreds (or, more likely,
> > thousands) of VDR systems out there with full featured DVB cards,
> > running just fine.
> 
> Nobody will force them, but these card have their limitations. You know
> them.

Yes, I know. But so far I was able to live with them or work around them.
I even fixed some issues myself, as you may remember.

You make all this sound as if I was affiliated with some DVB card
manufacturer and would actually earn money by luring people into buying
expensive DVB cards. This is not the case! Sure enough I wish the original
TT design would have been better, but unfortunately those developers
were apparently smoking crack at the time...

I initially wrote VDR just for myself and never expected it to become
as popular as it is today. If somebody downloads the VDR code today and
wants to build such a machine, and asks me what hardware to use, the simplest
answer still is "get yourself a full featured DVB card and everything should
work fine". I myself simply can't get into exploring other hardware options
or implementing software players - I just don't have the time for that.

Klaus


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