any application that can read straight form a tv tuner device?

Rick C. Petty rick-freebsd at
Thu Mar 8 20:55:32 UTC 2007

On Thu, Mar 08, 2007 at 02:46:42PM -0500, Jim Stapleton wrote:
> i.e.
> $ SomeMpegViewer < /dev/cxm0
> I tried mplayer since it was supposed to be able to handle mpg videos
> from stdin, however it gave me an error saying there was too much data
> per packet (I don't have it with me at the moment, so I can't say
> exactly what it is)


mplayer -cache 4300 /dev/cxm0

> I found that, if I have enough delay between the two commands,
> $ cat /dev/cxm0 > /tmp/tvfile
> $ noatun /tmp/tvfile

For some reason, I think the way the MPEG encoder multiplexes the audio and
video is problematic.  From analyzing the problem, it seems the audio is
multiplexed a few seconds later in the stream than the video.  Telling
mplayer to cache 4.3MB seems to fix this problem for me.  The timestamps on
the video & audio stream are correct, mplayer just need to "read ahead"
farther to find the correct timestamps.

> does the job I need, but, it has some latency, which can be
> problematic (especially if I were playing a console game), also it
> tends to create a rather large file, unncecessarily.

Yes it does and it is quite annoying.  "Live TV" is not live but delayed.
I'm wondering if this is a problem for Windows users and these cards.  I
was never able to get my card working in Windows, and Linux was almost as
broken.  I suspect there's not much we can do because the encoder's
firmware is downloaded to the card when the cxm driver is probed.  It *may*
be just a matter of tweaking settings, Usleep would have a better idea.

-- Rick C. Petty

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