jeffsimpson at alum
Feb 7, 2007, 12:02 PM
Post #12 of 24
(3411 views)
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Re: [ivtv-users] PVR-350 and MythTV support
[In reply to]
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> > #1, MPEG Output on the PVR-350 is working, but mostly unsupported by
> > advanced features. Things like fast forward and rewind don't work,
> > frequency scaling doesn't work, things like that. It does technically
> > still play video, but only native MPEG2 (no mpeg4, no alternate
> > formats, etc). The only way to play anything that isn't a native
> > recording is to use the framebuffer or xdriver, whose faults are
> > described later.
>
> However, the PVR350 allows you to use rather moderate hardware for a
> front- and backend (i.e.: my old P3 850 as combined front+backend and
> a PII 300 as a second frontend).
Only if you want a limited-use frontend. You can only play mpeg2 on
it, which means no automatic transcoding, no dvds, etc. It is a good
way to breathe life into older hardware, but I can't recommend this
card to anyone with a fast machine.
> > #2, Myth is moving to OpenGL for menus. It now supports OpenGL and qt
> > and you can switch between them. I can't imagine they will continue to
> > provide both options for much longer. The PVR-350 doesn't support
> > OpenGL and never will.
>
> I don't know the reason for switching to OpenGL, the Qt engine still
> works fine. One way to support OpenGL on the 350 would be to use Mesa,
> but that would be another layer of indirection that will slow down the
> system.
exactly. I did try that, but mesa made the framebuffer output on the
350 even slower than it already is. It was unbearable and took all my
CPU.
> > #3, Framebuffer is slow slow slow slow, and it EATS cpu. I have a 3ghz
> > machine, but the menus are still slow. I often find the X session
> > using 50 or 60% of my cpu, just SITTING there.
>
> Never seen that. An idle machine is just idle over here. Occasionally
> Xorg tends to eat 100% CPU time, but that seems to be unrelated to Myth
> cause the same happens occasionally on my desktop.
I see it often if I leave it in the list of recordings where it shows
a small preview, that alone will eat up 30-40% of cpu. actually using
it to display something eats more. The hacks to let you play a DVD or
other format of video through XV on the PVR output are just that -
hacks. They eat a LOT of CPU that a normal accelerated card would not
have to.
> > Forget trying to run it
> > at the same time as another X session, it jumps to a full 100%.
> > Playing anything that isn't a native mpeg2 video makes the system
> > crawl.
>
> If you only use PVR x50 cards to record the problem doesn't exist.
only if you don't auto-transcode to mpeg4, watch dvds, or use the myth
box for anything that isn't just plain old TV. Myth isn't just for
SDTV, it's supposed to be the everything box. I also can't use
mythgame on the PVR-350 at all, since it can't scale or accelerate.
Games like stepmania that would be great on a myth box can't be played
on a graphics card without openGL and acceleration.
> > #3 XDriver is a great project, but it's always been buggy at best, and
> > difficult to compile (with each version of X, the driver has needed
> > another patch or hack just to compile). I think now that it's in some
> > repositories (gentoo), it's better? (I've still had to patch it, but
> > maybe by now it's better).
>
> FWIW, it never crashed on me.
Mine doesn't crash either. But it is buggy. Switching VTs results in
garbage on one of the main screens on my other card when I use the
framebuffer, if I kill X and restart it, the screen is garbled until I
play an mpeg video, at which point it fixes it, small little bugs. And
a LOT of hacking around just to make it work in the first place. It's
not plug-and-play like a typical video card is.
> > So in summary, the PVR-350 *does* work, it just isn't as fully
> > supported as say, any nvidia or ati tv out card made in the last 5
> > years for 1/4 of the cost. The video encoding is well supported, just
> > like the 150/250/500, it's just the output that's flaky. In my own
> > personal opinion, having owned a PVR-350, I would say that I'd be
> > better off owning a 150 and an nvidia geforce card with TV Out.
>
> I diagree. A PVR 150 is about 85 EUR, for 140 EUR you have a 350. That
> difference does buy you a ati or nvidia card with tv out (cheapest is
> around 40 EUR), but doesn't buy you a CPU fast enough to do the
> decoding, especially when you have some old hardware lying around.
If you only want the bare minimum of what myth has to offer, than the
PVR-350 will do it. But if you want advanced PVR features like
"fast-forward" and "rewind", you need a supported card. It's sad but
it's true. I really like the idea of the PVR-350, the idea that the
hardware can do all the tedious decoding and save the processor for
the real work. The problem is not many people use the card, and as
such, support for it is lacking. It's the same reason I wouldn't want
to use an alpha or sparc machine. The architecture is great, but
software support is terrible.
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