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Old 01-30-03, 09:24 PM   #21
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Join Date: Jan 2003
Posts: 76

I have submitted the following summary bug report to:

I have a GF4 4600 (Leadtek Ultra A250 GF4 4600 128MB with VIVO/TVO) running under RedHat 8.0 with kernel 2.4.20. I am using the 4191 Linux driver.

When I play a video (of any format) at full-screen, the scaling
suffers from a pattern of interleaved black lines that ruin the
picture, making it look distorted with jagged edges and blurry.

Specifically, looking closely at the screen, it seems that instead of
properly scaling the picture, 1 pixel thin horizontal black lines are
interleaved between every few original image lines in a regular
pattern. It looks somewhat like this (where even between the
closest-spaced black lines, there are perhap 5 or 6 normal image





The effect is worse at full-screen than at double-screen. The result
is that the picture looks very jagged and blurry and thus is almost
impossible to view.

I have initiated a thread on this on the nVidia bulletin board
(, which has led to the following interesting observations.

1. The problem is independent of type of video or of video player
(this suggests that it is likely an X-server/driver problem)

2. If you begin with a normal size frame and gradually stretch the
picture, the black line effect suddenly appears when the picture gets to be about 3/4 the size of my 1280x1024 screen

3. The problem only occurs at some resolutions. In fact if you switch the X-server resolutions while the video is running
(ctl-alt-backspace) the "jaggie" effect comes and goes depending on the resolution. Specifically,
1280x1024: jaggies
1280x960: no jaggies
1152x864: no jaggies
1024x768: jaggies
800x600: jaggies
640x480: jaggies

4. INTERESTINGLY, if you start another video first and then start a
second video while the first one is still playing, then you can go to
full-screen without any jaggies. The picture remains good even after the first video completes. (Is it possible that the first video uses haredware scaling while the second uses software scaling???)

5. The problem resolves if I fix the vertical resolution at 60 Hz
(i.e., VertRefresh 60.0), but persists if I use the monitor
specifications of: VertRefresh 50.0 - 75.0 (this suggests maybe a
synchronization problem with the video frame rate???) [Note I have a digital LCD monitor]

6. Using different values for NvAGP has no effect

7. Using x11 vs. xv drivers has no effect

8. I have not had any other problems with the nVidia driver under RH Linux, including with games such as Quake

9. I think (but am not sure) that it worked ok under the 3123
driver. I have however not been able to downgrade to check it again.

So, in summary it seems to be something wrong with scaling that causes the problem that somehow is dependent on the screen resolution, vertical refresh rate, and whether or not another video is already running.

Any suggestions on what might be going on here?
I am stumped and frustrated?

Note that I am not satisfied with keeping the VertRefresh at 60, since I want to get the full 75Hz refresh performance of my monitor

Other details of my configuration include:
RH8.0/Linux 2.4.20
nVidea driver: 1.0-4191
Asus P4PE motherboard
Intel P4 2.53GHz
2 x 512 MB PC2700 DDR Kingston
Leadtek Ultra A250 GF4 4600 128MB with VIVO/TVO
Viewsonic VG171 17" Flat Panel
Antec 400W PS

XF86Config file includes the following excerpts
Identifier "NVIDIA GeForce 4 (generic)"
Driver "nvidia"
VendorName "NVIDIA GeForce 4 (generic)"
BoardName "NVIDIA GeForce 4 (generic)"
VideoRam 131072
Option "NvAGP" "1"
Option "DigitalVibrance" "2"
Option "CursorShadow" "1"
Option "RenderAccel" "true"
Section "Screen"
Identifier "Screen0"
Device "NVIDIA GeForce 4 (generic)"
Monitor "Monitor0"
DefaultDepth 24
SubSection "Display"
Depth 16
Modes "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
SubSection "Display"
Depth 24
Modes "1280x1024" "1280x960" "1152x864" "1024x768" "800x600" "640x480"
Fedora Core6/Linux 2.6.x
nVidea driver: 9631
Asus P4PE motherboard
Intel P4 2.8GHz
1.5GB PC2700 DDR Kingston
Leadtek Ultra A250 GF4 4600 128MB with VIVO/TVO
WinFast TV2000XP Deluxe
Dell 1901FP 19" LCD
Antec 400W Power Supply
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