[mythtv-users] Hauppauge 350: "cat /dev/video0 > test.mpg" then how to play back w hardware decode?

[Neil Sedger]

mark a stephens wrote:
> 
> So I tried boiling it down into a simple problem:
> 	cat /dev/video0 > test.mpg
> 
> 	cat test.mpg > /dev/video16
> produces the sound just fine.
> 
> Are there any mplayer settings folks have used to get the mpeg2  
> decoder of the H-350 to work?  Any other player software?


Umm I think that *should* work. Jarod's guide covers it. I'm sure I had
it working at some point - a good while ago though. See this snippet:

-----8<-------------8<---------

Another test you might have more success with is this, which will
attempt to play video off the card right back out to your TV:
# /usr/bin/ivtvfbctl /dev/fb0 -noglobalalpha -localalpha
# dd if=/dev/video0 of=/dev/video16 bs=64k
(control-c to stop)
# /usr/bin/ivtvfbctl /dev/fb0 -globalalpha -nolocalalpha

-----8<-------------8<---------


The reason your test above doesn't produce any picture could be because:
a) 'cat' does not pass the data through in the right-sized-chunks - try
'dd' as suggested above
b) the framebuffer isn't set up properly (loads on this in Jarod's
guide) so you can't write directly to /dev/video16
c) the alphas are in a mixed-up state so that the mpeg is playing but
being masked by a black overlay screen. An example is above and again
covered in more detail in Jarod's guide.


Once this is working with 350-produced mpeg files, try it with an
(unencrypted!) file from a DVD. It might work, I don't know how picky
the 350 is about its mpeg2 files.

I doubt there'd ever be an mplayer output module for the 350 since all
you need to do is 'dd' the mpeg data to it - no software
decoding/processing is required at all.




I have a similar setup to yours - with a Celeron500. I don't use the 350
as a decoder any more, I use a cheap (<£20) old GeForce 4 MX and it
plays MPEG-2 files just fine with mplayer (or Myth's internal player) as
long as I have XVMC configured correctly and switched on. Without XVMC I
get the same judderyness you describe.

(XVMC is partial hardware acceleration for MPEG-2 - not as good as the
350's onboard but it does enough of the work to allow a Celeron500 to
handle whats left)

I doubt the ivtv-xv driver (ivtv_xdriver_src_0.10.6) supports XVMC since
the 350 can do it itself as described above.



As an aside the new funky OpenGL GUI should work lovely on the cheap 
nVidia card, probably not so on the 350's TV-Out.


Neil