[mythtv] WinTV PVR-250 (hardware mpeg encoder)

Isaac Richards mythtv-dev@snowman.net
Fri Jan 10 21:54:58 EST 2003

On Friday 10 January 2003 04:00 pm, kevin thayer wrote:
> So getting back to the original topic of this
> discussion (and the part that is interesting to me)
> Provided that v4l(v4l2?) compatible drivers were
> available for this card, would supporting its hardware
> encoding of mpg2 be:
> A) Fairly trivial, like that of mjpeg
> B) More complicated, along the lines of finding a good
> mpg2 decoding library and integrating that

Between A and B, but closer to B.  Basically, to do it cleanly, there should 
be a new pair of classes like NuppelVideoRecorder and NuppelVideoPlayer.  The 
new recorder class would be very lightweight, basically just grabbing the 
encoded data from the card and pushing it to the ringbuffer class.  The new 
player class would just be a .mpg file format parser (could probably even 
just use ffmpeg's libavformat), tying into the existing decoder/video 
display/osd stuff.  A bunch of code could be shared between the two sets of 
classes and extracted out into a pair of base classes.  All in all, a couple 
days worth of work, as opposed to the couple hours it took for the mjpeg 

As for what the driver would need for mythtv, the best thing, IMO, would be 
for it to use the same v4l ioctls for changing channels and inputs, etc, as 
everything else does.  The actual grabber stuff isn't as necessary to work in 
the same fashion as the normal v4l code (like how the mjpeg stuff has an 
extended ioctl set for grabbing the compressed frames), since that's probably 
going to be custom code, anyway.


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