I recently destroyed my machine (R5A15.1) and had to install from scratch. When I installed I used R5A16. I noticed that some of the things weren't working as well as they were on my old install. For example, I was getting stuttering on playback unless I used libmpeg2. Also If I tried to use timestretch, it would stutter. My processor is an XP1700 (see here for my hardware details).

At first I put this down to the fact R5A16 has myth 0.18.1 and R5A15.1 had myth 0.18. But I started digging a bit deeper.

I compared playback using the nv driver with the nvidia driver. With my graphics card (GeForce2) the nvidia driver gave slightly better performance. The X server was using around 10% of CPU using the nv driver and this dropped to 2-3%. Everything else stayed about the same.

I compared playback using libmpeg2 as opposed to the native myth playback. libmpeg2 performed slightly better. I think it shaved less than 10% of CPU off the frontend task (which was using over 70% of the CPU).

With these two options, my playback was fairly smooth, but I still couldnt use timestretch to boost the speed much without running into stuttering. I thought that was the best I could do, but then I remembered the thing about selecting the mythtv modules during the install. I vaguely recalled taking the default (i586 modules). So I ran the install-i686 script to install the i686 compiled mythtv modules. And bingo. That was the difference. I went from 5-15% idle time to 30-50% and I can timstretch up to the full 2x.

So the lesson is, make sure you select the right modules when you install. I am wondering now If there would be even more improvement compiling specifically for athlon. I might also rebuild my kernel for the athlon processor and see if that makes things any better.

Perhaps someone who knows could define the point in processor history where you can use the i686 modules instead of the i586 ones. It would also be great if the installer checked your processor and made this decision for you!

is there possibly a way to check which modules you have installed? i just recently re-installed myswlf and have run into some odd artifacting in live/recorded TV that i'd never experienced before, and i haven't been able to track down the problem yet...

I don't think there would be any harm in just running the install-i686 script even if that is what you already have installed.

I'm sorry but as a relative newbie I really have no idea about what the difference between i586 & i686 is so reading a few posts on this has me wondering if I've installed using the right option...

I installed R5A26 using the default i586 option, and I am using a Celeron 2.4 GHz CPU - did I do the right thing?

What about if I stuck a Pentium IV 2.53 GHz in there instead (they both have the same socket 478 pinouts) - would that change what I should select?

And finally, IF I have done the wrong thing, what can I do to rectify it? (ie. how do I run the install-i686 script, and will it stuff up any of my current MythTV settings?)

586 = Original Pentium
686 = Pentium II and above, Athlon etc

If my understanding is correct, any modern PC should be using the i686 compiled mythtv.

Thanks - so it looks like I made the wrong choice

I think the instructions here http://www.mysettopbox.tv/doc.html could be made a little clearer in this regard, as it says "select which package you'd like to install i586 (Pentium class processors, K6, C3, etc.) or I686 (PentiumPro class processors, PentiumPro and above, Athlon and Duron). The default is i586 which is compiled w/ LIRC. If you have an i686 class processor, select i686 then LIRC." which I inferred (incorrectly) to mean "if you've got a CPU with Pentium in the name use i586; but if you've got anything else use i686" D'OH!

I'd rather not reinstall from scratch and lose all my settings - is it OK just to run "install-i686" from a console (which I am inferring is the thing to do, going by Greg Frost's second post, above), and/or is there anything else I should bear in mind before trying this? Eg. do the i586 modules first need to be uninstalled somehow?

Hi,

This is the content of the install script install-i686


And this is the code of install-i686-I



In this thread
http://mysettopbox.tv/phpBB2/viewtopic.php?t=4708
you can find some info. A post of cesman suggests, that the database will not be touched...but it never hearts to make a backup before running install-i686

F.

Thanks Fiete - is there any difference between the two scripts above I can't see any

Neither do I. Just have had a look into all install-i686* scripts...

F

All the x86-xzy scripts are symlinked to the x86 script. Since MythTV has evolved and most everything can be compiled in now, there is no need for the additional scripts.

_________________
cesman

When the source is open, the possibilities are endless!

OK, thanks. One q: before and after I execute the above code, is there anything I can type in, in order to confirm which (i586 or i686) modules are currently installed?

Hi,

This install script makes a little file


You can look into this file before (should be 'MythTV-i586') and after running the script.

F.

OK, but that's kind of 'cheating' since it isn't really querying which modules are actually installed, it's only looking at the contents of a text file that the install script creates, ie. if you left out the last line of the script, you may have the i686 modules installed, but the mythtv-version file would indicate otherwise. In other words, if you had deleted the mythtv-version file, how could you then find out which modules you had installed?

Hi Ralph,

I googled 'query installed packages debian' and found that the database of installed packages can be queried like (as root I assume)


I found, that the man page is informative for other options. I've tried that on my box and the abovementioned command listed the myth packages, and for some packages the -586- in the info.
These should be the actually installed packages. Hope that this helps!

F.

Ah, thanks! Actually I got a better display of which version was installed by using

I then used your coding and it seemed to go well - got a lot of warnings flashing up about it 'downgrading' from i586 to i686 but I guess that's just an ideosyncrasy of the process?