[mythtv] Loud hard drive due to NuppelVideoRecorder.cpp sync()

Chris Pinkham cpinkham at bc2va.org
Fri Jun 13 11:15:42 EDT 2003

> One final thought.  Many people seem to have noticed a slow down with
> version 0.9 (for now I've been sticking with 0.8).  I haven't fiddled with
> it yet, but I was wonderring if the "position map" database write that
> occurs every key frame may be the culprit (it comes right after the sync()
> call in NuppelVideoRecorder.cpp).  There's also the call to the somewhat
> kludgy looking "KickDatabase" function which I'm not totally sure about...
> ;)

The positionMap write only gets done every 15th keyframe which is once every
15 seconds and it only writes out the new entries which haven't been written
yet so it's pretty quick.  I don't notice any problems on my Athlon 700
recording at 352x480 using mpeg4 and running the backend and the mysql
server and that's a pretty low-end MythTV box.

You'll have to ask Isaac about the KickDatabase stuff, that's not my code
but the "write positionMap every 15 frames" stuff is.

I haven't noticed any slowdown as 0.8 developed into 0.9 and I try to
keep synced with CVS.  My under-powered Athlon hasn't started skipping
frames or anything and I'm doing a pretty good job of pushing it to the
limit anyway.


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