[mythtv] [ivtv-users] [ivtv-devel] PVR-350 and MythTV support

Hans Verkuil hverkuil at xs4all.nl
Fri Feb 9 13:17:09 UTC 2007

On Thursday 08 February 2007 15:35, Jeff Simpson wrote:
> > > 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.
> >
> > That's what I use it for: an advanced VCR.
> VCRs can fast forward and rewind. The PVR-350 can't, it's not
> supported.

Not true. The PVR350 supports it, it is just never implemented in 
MythTV. I'm working with the video4linux guys to make a standardized 
API available in the ivtv driver to do this. That should make it much 
easier to implement. Although if anyone is interested I do have example 
code available that demonstrates how to use the current ivtv API for 
fast forward/rewind.

(You can get it here: 
http://ivtvdriver.org/viewcvs/ivtvtv/trunk.tar.gz?view=tar, file 
ivtvtv.cpp. Note that this is code for testing the pvr350, not 
production code.)

Basically the PVR350 is just that: a PVR, intended to be used in 
hardware recorders and things like that (and I know it is in fact used 
in some HW recorders). It's not for mpeg4 playback, etc. Although you 
can use a software decoder and XV to do the playback. The XV stuff is 
pretty efficient as it uses DMA to get the picture to the card, but 
using the framebuffer directly is really inefficient as it uses PIO to 
get the data to the card, which is a notoriously slow method.

But if you want to play 3D games at 100 Hz refresh rate, then you're 
using the wrong card :-)

The same is true for DVD playback: it isn't designed for that 
(unfortunately). Again, you can use XV for that so you can at least 
utilitize the excellent TV-out quality of the PVR350.

To summarize: the PVR350 is great when used as a PVR, if you are not 
interested in that, or if it is only a small part of what you use 
MythTV for, then choose another capture card. But I suspect that most 
people use MythTV as a PVR first and foremost.

BTW, if anyone is interested in improving the PVR350 support in MythTV 
then I'd love to help out with advice and example code. It's not 
something I'm going to tackle myself though out of self-protection: 
ivtv is already taking up too much of my time and I'm not going to add 
another project.



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