[mythtv-users] how to determine nvidia-setting vblank options

Steven Adeff adeffs.mythtv at gmail.com
Wed Jan 31 15:35:17 UTC 2007

On 1/30/07, Nate Crosno <nate at crosno.net> wrote:
> Hi All,
> After lots of searching on how to get 1080i going right (I have a list of
> things to try tonight, but that's another story), I am very confused on when
> and why to choose the various nvidia-settings vblank options.  Mostly, I have
> found lots of posts that say "turn this on" or "turn this off", but I cannot
> find any rhyme or reason to it.  Perhaps I am dense (likely), but frequently,
> the instruction are not clear which of the 3 options are being referenced.
> I am hoping to understand these settings better so I can choose them under the
> right circumstances rather than flailing in the dark and hoping to eventually
> pick the right ones.
> In an effort to be more clear, here are the 3 options I see in the file
> "~/.nvidia-settings-rc"
> localhost:0.0/SyncToVBlank=0
> localhost:0.0/XVideoTextureSyncToVBlank=0
> localhost:0.0/XVideoBlitterSyncToVBlank=0
> So far, it looks like if component out is used, then all the above should be
> "0", according to http://www.mythtv.org/wiki/index.php/ComponentOut
> Steven Adeff (who has been of great help!), recently advised me:
>  > Then turn on Xv Vsync in nvidia-settings and use the Standard decoder.

This is mostly a 9xxx vs 8xxx series issue. the 9xxx series introduced
a "UseEvents" option, which when enabled will let you turn on Xv Vsync
without issue. From what I read on the ComponentOut page, the
recommendation is based on the 8xxx drivers.

> However, we were talking about DVI at the time.  I am confused about which of
> the three this is. Is it the "textures" or "blitter or both?"?
> The XvMC wiki page mentions this:
>    "Try using the 'nvidia-settings' control panel to disable Video Texture
> Adapter and/or Video Blitter Adapter "Sync to VBlank" checkboxes (on the "X
> Server XVideo Settings" page)"
> That must be the second two items I listed from the rc file.
> If anyone has more information on what these really do and under what
> circumstances they should be turned on/off, I'd be grateful.

With the 9xxx series (and if your doing HD you really should be using
the 9xxx series IMNSHO), just set the UseEvents option to True and
enable the SyncToVBlank. I don't think Myth uses textures or blitter
in any significant way, I never noticed a difference either way with
them enabled or disabled.

> Thanks,
> Nate
> p.s. I did read "How To Ask Questions The Smart Way" -- Hopefully I am doing
> better ;-)  critiques welcome.

looks good to me

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