[mythtv] Experimental pvr 350 output patch

Isaac Richards ijr at po.cwru.edu
Wed Dec 17 21:51:30 EST 2003


On Wednesday 17 December 2003 09:32 pm, David Engel wrote:
> How fast is the RingBuffer at seeking backwards ~32-96k?  Becuase I'm
> using non-blocking I/O for the mpeg data, the entire buffer usually
> isn't written.  If we don't buffer the data in ivtvdecoder, we either
> have to seek backwards evertime or only write 32k, driver-friendly
> chunks at a time.

It wouldn't be very fast right now, but I don't think it'd take too much 
effort to make it speedy.  Just would have to have it not fill up the entire 
buffer so there's always at least X amount of data before the current read 
position, and write a little bit of code in the seek call to take advantage 
of that.

> Good.  I'll start preparing a message for Kevin and the ivtv guys.  I
> know he's getting ready to release a new version, so hopefully I can
> get the required changes in, in a backwards compatible manner, before
> the new release.  Then, we can worry about commiting the Myth changes.

Well, hopefully there'll be a versioning number we can ask the driver for at 
some point in time and bail if it's too old..

Are you going to add some ioctls for the direct firmware calls you're 
currently using?

> Yeah, I know, but at least it's functional.  I've got some ideas for
> future improvements, but I want to get the existing stuff accepted and
> handle some other todos before doing anymore with it.

Oh, I wasn't saying it was bad or anything, just funky =)

Isaac


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