[mythtv] Separate Record and Play boxes? (system design)

Isaac Richards mythtv-dev@snowman.net
Thu, 19 Sep 2002 21:02:24 -0400

On Thursday 19 September 2002 11:13 am, Grant Taylor wrote:
> Well, this is interesting.  DVD rate is circa 1.5Mbps, IIRC; rtjpeg
> tends to produce more data.  But I bet it still fits, certainly so if
> mpeg4 is used.
> What I wonder about is this buffering - mythtv uses a "ringbuffer"
> structure which doesn't appear to implement very much buffering.  And
> the primary difference between my system (which jitters excessively)
> and Isaac's (which generally doesn't jitter) appears to be disk speed
> (5400 vs 7200) and some marginal memory settings on his part.  This
> suggests that mythtv may be more susceptible to filesystem
> irregularity than mplayer (which works fine for me every which way,
> too).
> Issac, could you describe how the coder and decoder threads interact
> with the files?  It appears that they coordinate through the
> RingBuffer class, but that the file reads and writes actually happen
> in the coder/decoder threads themselves?

Well, the RingBuffer is basically just a wrapper around all the read/write 
calls in the recorder and player.  It's not meant to do any sort of 
buffering, though it certainly could be made to.

Can you change line 1167 of NuppelVideoPlayer.cpp to something like:

    usepre = 8;

and see if that does anything? It'll prebuffer more that way, and that might 
help a little.