[mythtv-users] re: choppy HD playback

John Sturgeon john at sturgeonfamily.com
Wed Apr 21 11:53:25 EDT 2004

HI Brandon,

I'm wondering what you use to transcode your HD nuv files.  Do you use 
nuvexport, and if so what output format and settings do you use.  I too 
have a 2600+ and find 1080i to be 'less than optimal'.


John Sturgeon <><

Brandon Beattie wrote:

> I run an amd 2600+, I have problems running 1080i also.  It will run
>fine if you turn of de-interlacing in the tv playback setup.  However,
>the current algorithm for deinterlacing does not work well for high
>resolution files (Such as HD).  At one point someone mentioned they were
>going to write a couple new deinterlacing algorithms to help, but that
>was a couple months ago.  In the future, your 2500+ /may/ be okay.  Most
>of the problem with HD streams is not really myth, but the X server.  X
>is very poor when trying to display HD.  (Not to mention it does not do
>a good job at syncing frames and keeping video smooth).  When X is
>re-written (as there is a project going on for this now) it will work
>much better and will have true v-blank support.  You should be able to
>watch 1080i on about a 1.7Ghz (This is what is required for windows that
>properly handles v-blank and has a good de-interlacing for HD I've been 
>told).  I personally recommend a P4 3.0Ghz with HT.  It almost doubles
>your speed in regards to decoding HDTV and letting X suck up more
>CPU cycles than it should really need.  The same stream on my 2600+ that
>maxes out my CPU and is basically unwatchable, takes about 70% CPU usage
>on a P4 3.2Ghz with HT.  Other possible issues are the way mythtv scales
>video that is not native display size.  Right now, I (try to) transcode
>all programs to 1024x576 (my native display size).  Transcoding is a bit
>broken right now, but this takes care of things for me, but I don't
>watch livetv, and this also saves disk space.  I also recommend a higher
>CPU because if you want to transcode, the border line is not good.  Even
>when watching transcoded shows, if the transcoder kicks in I can notice
>it on my 2600+, the P4's with HT don't appear to be noticible.  I'm
>waiting a bit to see if I can't find a dual P4 MB for cheap in a half
>year and I'll pick up one of those for my mythbox.  Transcoder can use 1
>processor, and my dvd, or livetv (If I do use it) can use the other.
>That's my $.02

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