[mythtv-users] XvMC OpenGL nvidia build question

[Michael T. Dean]

On 09/14/06 15:22, Tom Lichti wrote:

>Michael T. Dean wrote:
>  
>
>>On 09/14/06 11:10, Tom Lichti wrote:
>>
>>>jack snodgrass wrote:
>>>
>>>>Not sure if this is x86_64 specific or not... that's my build platform
>>>>but it's probably not related to that...
>>>>
>>>>What options do I want to pass to configured to use the nvidia xvmc libs?
>>>>
>>>Not sure. I hacked the configure script to do what I wanted, but I know 
>>>what I did is not correct (as in useful for the masses), but it worked 
>>>for me. I basically just remove the xvmcw option, so it hits the nvidia 
>>>stuff.
>>>
>>In truth, you don't want to use it...
>>
>>http://www.gossamer-threads.com/lists/mythtv/commits/203600#203600
>>http://www.gossamer-threads.com/lists/mythtv/commits/202450#202450
>>
>Aha. I forgot about those commits, however, why are so many other people 
>having issues if this is so hard to implement, I wonder?
>
I don't think I understand the question you're asking, but here are my 
best guesses:

Q: Why is it hard to enable?
A: Daniel tried to make it harder to accidentally enable the setting (by 
making sure it's /only/ enabled if you explicitly specify the 
"--enable-xvmc-opengl" argument to Myth's configure script and link 
against NVIDIA's libraries directly) because when the default was to 
enable it, people with NVIDIA cards and no XvMCW would automatically get 
it and then have performance problems.

Q: Why are so many people trying to use it if it shouldn't be used?
A: Myth users (in general--as evidenced by the "--disable-frontend" and 
"--disable-backend" configure arguments and 
http://cvs.mythtv.org/trac/changeset/10963 ) often see a setting and 
think, "Hey, that's cool.  I'll use it!" without taking the time to 
research it and figure out what it means and whether or not they 
/should/ be using it.  So, a lot of people get 0.20, see that there's a 
configure argument that wasn't there before, and work as hard as 
possible to figure out how to enable it.

Q: Why shouldn't it be used?
A: Support for the XvMC OpenGL texture method is not yet complete and 
tends to cause poor performance.

Q: Why are many people having performance issues if the likelihood is 
they didn't enable this setting (since it was made more difficult to 
enable than others and some have resorted to hacking configure to enable 
it ;)?
A: They have different configuration problems unrelated to this setting.

Hope I guessed right on one of these.

Mike