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

[Holger Waechtler <holger@convergence.de>]

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.


> > 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.


> > 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?


> > 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.


> > 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.


> > 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 :)


> 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.

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


> 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.

Holger



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