Re: [SLUG] video capture card

From: Glen (gurensan@tampabay.rr.com)
Date: Wed Apr 10 2002 - 12:29:05 EDT


So is the big difference between a TV capture card and one of these PVR
cards/tivo, is that a TV capture card will need software that knows what's
coming on when, has no hardware decompression, and no extra TV out?

What's stopping people from writing software that grabs show listings from
tvguide.com and sorts that into a database? The only real thing needed after
that is the decompression, and maybe you could bind a software process for
that to a specific CPU on SMP systems.... Sounds like fun, when do we start?

        Glen

On Wednesday 10 April 2002 11:20, you wrote:
> On Tue, 2002-04-09 at 22:56, Paul M Foster wrote:
> > I've seen one major disadvantage of not letting Tivo phone home (the
> > Tivo service): clock drift. The Tivo is a little computer, and its time
> > will drift if it's not allowed to sync with the home office. I've also
> > noticed that, if you don't let it phone home, after a while, it will
> > lose future scheduled recording dates. However, cancelling and resetting
> > just one of them will reset the future schedules for them all. Peculiar
> > bug I haven't fully tracked down.
>
> You also won't be getting software upgrades. If you're running the 2.0
> version of the TiVo software, though, I'd recommend not upgrading. I
> liked it better than the 2.5 that is currently on my TiVo. That's one
> downside - I'd love to be able to tell the unit to downgrade itself to a
> previous version. I can understand why the service wouldn't want that
> though - support nightmares if everyone were running different versions.
>
> The biggest advantage, for me, of the TiVo *is* the service, though. I
> LOVE not having to dig through TV listings to find the shows I want to
> watch. I just click the "search by name" option, put the show title in,
> then click "record" and don't worry about when it's going to record it.
>
> That, and the ability to do "Season Passes" where the TiVo will find any
> time any channel a particular show is on and record it for you, are
> worth the $9.95/mo for me. Except that it's going up to $12.95/mo
> sometime soon. It's still worth it. (There's also the $100/yr and
> $200/lifetime options, but I've stuck with the monthly for now.)
>
> > Anyway, I'm interested in setting up a Tivo-like device on a regular
> > computer. If anyone does it, I'd like to know more about it. A couple of
> > unknowns I see are how you get the software to know what the channels
> > are and then change them on time. And how do you compare such a system
> > with a 19" - 36" television? Viewing programs on a 15" or 17" computer
> > screen seems like it wouldn't be a lot of fun. And how do you connect it
> > to a cable box or VCR, etc?
>
> I've been working on this on-and-off for a few months now, so I've got
> plenty of experience.
>
> If you're willing to choke down having a Windows box do all the hard
> work for you, there are two pieces of software out there: ShowShifter
> and SnapStream. ShowShifter looks and acts more like TiVo and you watch
> the shows directly inside of ShowShifter, where SnapStream has a goofy
> web-based interface to do the recording and need to use Media Player to
> watch anything. ShowShifter is still under active development where you
> download weekly (or so) beta versions to install over the version you
> are currently using, where SnapStream is more shrinkwrap with "clean"
> 1.0 and 2.0 releases. They're both awkward, but ShowShifter is a little
> more intuitive as a PVR application. Of course they're both commercial,
> and you're just about better off just buying a TiVo, since it'll work
> much better.
>
> There are many other half-assed attempts at PVR software under windows,
> usually stuff that gets bundled with video capture and tuner cards.
> Mostly they just act like an AVI/Windows Media recorder that you
> manually tune a channel and click the "record" button. ATI supposedly
> has some fancier PVR type application bundled with their new Radeon
> cards, and Happauge has a whole line of capture cards, including an
> MPEG-encoding box specifically designed to be PVR hardware (costs $300
> of course) with its own software. All of this stuff runs under Windows
> as well.
>
> As far as anything that runs under Linux, there are not many options.
> There is a piece of software called 'vcr' that more or less works, but,
> like everything else along these lines under Linux, requires a lot of
> bleeding-edge libraries. I've been able to get vcr to work on occasion,
> but mostly it has problems recording or, it will record something, but
> then the format it's decided on its own to record is something I can't
> play. (it uses the avifile stuff, which is a linux layer on top of
> windows AVI DLLs, so is flaky at best.)
>
> The closest thing I've been able to get working is the "mjpeg-tools"
> that are built to work with the BTTV drivers. If you're lucky enough to
> have a supported card with MJPEG in the hardware, you can use the tools
> to change channels and record things and encode with MJPEG hardware
> support. If you just have a normal TV tuner card with no hardware, you
> can do software MJPEG, but expect to need something in the neighborhood
> of a 1Ghz Athlon to get 30fps at 1/2 TV resolution. Playback of MJPEG
> compressed files can be done with Heroine Virtual's "xmovie" software.
>
> Then there's the Linux DVR stuff that was announced on Slashdot the
> other day. Unfortunately, it ONLY works with a specific chipset of
> digital tuner card that is mostly used in Europe and a very few places
> in North America, so is almost entirely useless for us Yanks. I imagine
> with some Slashdot exposure, though, someone will probably hack into it
> to make it support a wider range of cards.
>
> The biggest problem under Linux is that full Broadcast Quality recording
> (30fps, ~640x480) REQUIRES hardware compression. I've tried various
> software encoders on my 1.33Ghz Athlon at home and the best I've been
> able to do is about 60% CPU utilization at 1/2 broadcast resolution,
> 30fps, or about 8-12fps at broadcast resolution with 100% CPU
> utilization. But when those 2.6Ghz Athlons are available, then maybe
> software-only encoders will be feasable.
>
> And of course, there are very few hardware encoding boards that are
> supported under Linux. The Happauge WinPVR card has someone attempting
> to write drivers for it but at the moment, all he has working is the TV
> tuner part, not any of the encoding stuff. The Iomega Buz and related
> cards that use the same chipset have a driver and are supported with the
> mjpeg-tools, but lack a TV tuner - they're only video-in cards.
>
> Unfortunately, in the current regime of DMCA and SSSCA and the RIAA and
> MPAA suing the pants off of anyone and everyone who looks like they
> might have something to do with possibly allowing the end-users to do
> anything other than what the studios absolutely demand be allowed for
> broadcast media, it's unlikely that anyone is going to make a PVR type
> card with available Linux drivers. It's too close to saying "This card
> can be programmed to do whatever you want, therefore it can be seen as
> violating the DMCA as a 'circumvention device'" and they'll get sued
> into oblivion. So for now, you'll probably only ever see Windows-based
> hardware that supports all the crappy Windows Media rights control stuff
> that keeps you from doing what you wanted the thing to do in the first
> place.
>
> Personally, I'd seriously consider the Sonicblue ReplayTV. The new 4000
> series has the ability to stream programs from one unit to another, and
> the protocol used has been reverse-engineered, so there is software out
> there that will let you stream a program from a ReplayTV unit into a
> local MPEG player on your computer, which is really the main reason *I*
> would want a computer-based PVR - so I can archive the shows I really
> enjoy.



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