11_textured_video_option.patch breaks XvMC

[Tore Anderson]

Binary package hint: xserver-xorg-video-intel

It seems Ubuntu has applied a patch which disables textured video by default - even though the comments in the patch itself say that the default is to leave it enabled.

This breaks XvMC, and in order to get it enabled you need «Option "TexturedVideo" "true"». This option is completely undocumented, and I needed help from the upstream driver developer at the xorg list to track down why it didn't work. He was completely unaware that Ubuntu shipped with such a modification, and I suspect this will quickly become a FAQ if Intrepid is released without this patch removed (or at least defaulting to what it says it does).

If there's a good reason for disabling this feature by default please add some info about it in the X output so that it is possible for a mere user like me to on my own figure out what's going on. Documenting the option (and the rationale behind it) in the driver's manual page wouldn't hurt either.

Regards,
Tore

[unggnu (unggnu)]

It is disabled because it doesn't work well on most systems atm. With i915 e.g. textured video isn't usable (painfully slow. tearing effect ...) even if it is activated by default from upstream and there are some reports which confirm the same behavior with i965 hardware (e.g. Bug #152206).

[Timo Jyrinki (timo-jyrinki)]

The textured video is unbearably slow in some windowed playback situations even on i965, if compiz is being used. Overlay is smooth.

[unggnu (unggnu)]

According to http://en.wikipedia.org/wiki/XvMC#Intel XvMC on Intel hardware works only with MPEG2 which doesn't bother CPU even on old hardware so I guess it is no real issue at least against to the penalties with textured video.
So mainly your bug report is about adding the TexturedVideo option to the Intel driver man page?

[Tore Anderson (toreanderson)]

Yes, the bug report is mainly about the complete lack of documentation (even the comments in the patch itself incorrectly states that the option is default off).

I wanted to check out XvMC since I'd seen it mentioned as the best output driver for MythTV. I've no idea if that is actually the case, I didn't notice any difference between plain XVideo and XvMC neither with MythTV nor MPlayer on my G33 so it while it seems to work correctly, it's no great loss for me that it's deactivated by default.

However - I spent _a lot_ of time trying to figure out why XvMC didn't work, even subscribed to the xorg list and got help (in the form of patches adding more debug output) from a upstream Intel developer. When I finally figured out that the Ubuntu package silently disabled the feature I was a bit upset for having wasted both my time as well as the Intel developer's time (he didn't know Ubuntu did this either). In my opinion, this should have been at least added to README.Debian and the intel(4) manual page. Even better, by extending the patch further a warning could be printed to the X server output:

if(!pI830->TexturedXvEnabled)
  xf86DrvMsg(pScrn->scrnIndex, X_WARNING, "Textured video / XvMC is disabled by default in the Ubuntu driver release, see /usr/share/doc/xserver-xorg-video-intel/README.Debian for more info.\n");

Untested but should be obvious enough...

Anyway, on the thread I started on the xorg list the following was posted:

> I don't think a (default) option to just disable texturedvideo really is
> the way to go, if it's desired that overlay video is the default (at
> least for now), just the order of the adapters should be switched (so
> make the order of the adapters a configure option instead to fix apps
> which just pick the first adapter).

-- http://lists.freedesktop.org/archives/xorg/2008-June/036648.html

I don't know if this suggestion has merit, but thought maybe you'd find it interesting.

Tore

[Ranulf WolfSage (ranulf)]

I'm sorry, bit of a n00b here, but would you add the [CODE]Option "TexturedVideo" "true"[/CODE] to the xorg.conf under the device section for the display driver, or elsewhere. I'm facing an issue where a game keeps complaining the card doesn't support textured video, and I believe this is the resolution, just not sure where I would put the notation. Thanks!

[Ranulf WolfSage (ranulf)]

Never mind, saw the comment on the linked article and applied it, still no luck though. My apologies for the interruption.

[Anton Blanchard (anton-samba)]

I was hit by this and only worked it out after I downloaded the ubuntu source and noticed that the original TexturedVideo patch had been changed. A comment in the Xorg.log would have saved me a fair amount of time.

[Anton Blanchard (anton-samba)]

After a quick look around, it seems someone has created a patch that does what is suggested above, ie prefer overlay:

http://lists.freedesktop.org/archives/xorg/2008-March/034142.html

[Anton Blanchard (anton-samba)]

The reason this is a bigger issue on the new G4X chips is that it appears they cannot do overlay:

/* mark chipsets without overlay hw */
#define OVERLAY_NOEXIST(pI810) (IS_GM45(pI810) || IS_G4X(pI810))

So the current patch disables all xvideo support on them, which is wrong. The patch to change the order overlay and textured video is configured sounds like the way to go.

[Timo Aaltonen (tjaalton)]

Fixed in intrepid, since the patch has been dropped. Textured video seems to work fine now.

[khelidan (khelidan)]

Intrepid on my laptop,with i915 intel chipset,with texured video i have problem of tearing video again