[mythtv-users] Freevo, Tivo & MythTV

[Rudy Zijlstra]

Marco Nelissen wrote:

>Sure, *IF* there is only a keyframe every so often. However, given that
>I can switch channels AND get a good picture when using my TV's built
>in tuner, and also with mplayer using the tuners in my mythtv box, all
>being fed the same signal, I can say with confidence that keyframes
>occur much more often than every 2, 3 or 4 seconds.
>  
>
Hmmm, considering the .nl country designation, i'll assume your posting 
from the Netherlands. This means the likelyhood your inbuild TV tuner is 
for digital is very, very low. There are some TV's on the Dutch market 
with inbuild DVB-T, and most of them actually are useless, as they 
cannot handle the Digitenne encryption......

So in this case at least you are comparing analog to digital. Not a good 
comparison.

Next question: what tuners are you using in your PC? Considering you are 
using mplayer they can be either analog or digital.

I've posted some data a while ago, showing that there are differences 
based on type of input.
PVR500 (2s) perform better than DVB-S (4 - 6s) cards. And i can compare 
to a recent DVB-S STB, which happens to have a consistent 2 second 
channel change time on SD and about 3 -4 seconds on HD channels.

With respect to I-frames, those are transmitted several times / second 
in Europe. We are not using the infamous Motorola system where you may 
actually need several seconds to build a full image from B-frames.

With respect to my DVB-S cards, i strongly suspect that has to do with 
incorrect tuning code. Partly driver error, partly MythTv. Last months 
some significant improvements went in. It used to be  signficiantly 
worse, as tuning often failed at all. Yeasah did some very good work at 
that. I expect to be experimenting soon on how good, when i add a Diseq 
swith to my setup.....

Now one thing we could do, is find out under what circumstances things 
are quick, and when they are slow. And document this including amount of 
time taken to change channel. So not "slow" or "fast", but: so many 
seconds, on this hardware setup.
I am measuring on a separate frontend, with the PVR500 on the master 
backend with local storage, and the DVB-S on a slave backend storing 
over NFS to the master backend.

cheers,

Rudy