[GM45] Bad chroma upsampling on videos
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
xf86-video-intel |
Fix Released
|
Medium
|
|||
xserver-xorg-video-intel (Ubuntu) |
Fix Released
|
Low
|
Unassigned |
Bug Description
I'm using Ubuntu 9.04 64bits with xserver-
https:/
[ lspci -nn | grep VGA ]:
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07)
Description of the problem: Whenever I view videos (with totem-gstreamer or mplayer), I can see red pixelation in reds.
Here you can see what it looks like (taken from a thread on Doom9's forum discussing this problem on Windows : http://
http://
I've attached another screenshot that I made myself below.
After some research, I found out this problem may be due to bad chroma upsampling. Below is an explanation I read on the Doom9's forum:
"Well, since our eyes are less sensitive to chroma than to luma (i.e. we notice changes in brightness more than changes in color) video is usually compressed with the chroma (i.e. the color information) at half the resolution of the luma (brightness information) - that's part of what makes YV12 what it is.
For conversion back to RGB (which is what displays, well, display) you of course need to scale the chroma data so it's the same size as the luma data, and if you get blocks it has been done by point resizing (i.e. by making every "chroma pixel" twice as big), whereas my shader turns the point resizing into bilinear resizing (i.e. I interpolate between the existing values to make the chroma smoother)."
This problem occurs with SD (DVD) and HD (Bluray) progressive content.
I've already filed a bug on buzilla freedesktop: http://
[lspci]
00:00.0 Host bridge [0600]: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub [8086:2a40] (rev 07)
Subsystem: Lenovo Device [17aa:20e0]
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07)
Subsystem: Lenovo Device [17aa:2114]
Related branches
Changed in xserver-xorg-video-intel (Ubuntu): | |
status: | New → Confirmed |
description: | updated |
tags: | added: gm45 intel jaunty videoplayback xorg |
Changed in xserver-xorg-video-intel: | |
status: | Unknown → Confirmed |
Changed in xserver-xorg-video-intel (Ubuntu): | |
status: | Confirmed → Triaged |
Changed in xserver-xorg-video-intel (Ubuntu): | |
importance: | Undecided → Low |
Changed in xserver-xorg-video-intel: | |
status: | Confirmed → Invalid |
Changed in xserver-xorg-video-intel: | |
status: | Invalid → Unknown |
Changed in xserver-xorg-video-intel: | |
status: | Unknown → Fix Released |
Changed in xserver-xorg-video-intel: | |
importance: | Unknown → Medium |
Changed in xserver-xorg-video-intel: | |
importance: | Medium → Unknown |
Changed in xserver-xorg-video-intel: | |
importance: | Unknown → Medium |
Thank you for reporting this bug and for providing your analysis. Do you see this problem when you are using the stock Jaunty 2.6.3-0ubuntu9.x versions of the intel drivers as well? (so that we know if this is a problem for stock Jaunty or just someting to be fixed before Karmic)