Video playback shows fault lines where it looks like parts of two frames are being spliced together (edit: called "tearing")

Question

I'm using Gentoo Linux with 3.8.13 x86 kernel at home and 3.10.4 x86_64 kernel at work.

When I'm watching 720p or 1080p HD .mkv containing a H264 MPEG-4 video in full screen mode (VLC, mplayer) I'm frequently seeing strange lines, that are little bit annoying. They appear as I guess on key frames.

Here's a screenshot. Because it's impossible to describe the issue. Take a look at Obi-Wan's forehead:

I already tried to enable deinterlacing with Yadif and Yadif 2x as suggested on various forums around the Internet, but it didn't help.

I'm using CONFIG_HZ_1000=y in my kernel config, and I tried with CONFIG_HZ_100=y, it doesn't seem to make any difference.

Any help greatly appreciated!

UPD1: GPU acceleration cannot be enabled or disabled:

UPD2: No luck with VSync enabled:

xrandr -q --verbose | grep 1280x800
LVDS connected 1280x800+0+0 (0x1e1) normal (normal left inverted right x axis y axis) 331mm x 207mm
  1280x800 (0x54)   71.0MHz -HSync -VSync +preferred
  1280x800_60.00 (0x1e1)   83.5MHz -HSync +VSync *current

UPD3: After enabling VSync, I changed video output in VLC to OpenGL GLX (XCB).

Now everything works flawlessly!

Thanks a lot to everybody who helped, and I hope this will help anyone facing the same problem!

Answer 1

It looks like vertical tearing to me, which means that your GPU is pumping out frames faster than the screen can display them. This is typically a more common issue with games and other interactive things, since video playback typically has V-sync enabled.

If you're using GPU acceleration in VLC, try turning it off ("Inputs and Codecs" tab in Preferences, there's a "GPU Acceleration" checkbox) and see if it makes a difference.

You can also try forcing V-sync driver-side and see if that makes a difference.

Answer 2

This doesn't look like an issue with any specific frame. Rather, it's probably your video card being too overwhelmed to display the video without lagging. Do you notice more tearing with higher-resolution videos? More pixels means more work for your hardware. High framerates can cause also more work, as it has less time to process all those tiny pixels in a given frame.

You should try experimenting with different Video Output drivers. IDK about VLC, but Mplayer does best with XV. If you and use XV with so-called "adaptors", that may help improve your performance even further (eg, -vo xv:adaptor=0). If you still experience tearing, you can try using software scaling to reduce the resolution (-vf-add scale=720), if you have a fast CPU.

If all of the above fails, your GPU probably just plain isn't fast enough for HD video. You could try buying a newer, faster model. Or, you could probably use a video converter program, such as FFMpeg, to convert the video at a lower resolution. If you don't like command-lines, you could also use XMedia-Recode (a Windows-based GUI), as it works quite well with WINE. The homepage is in German, but you can download it from Video Help, if you feel more comfortable getting it from an English site. Either way, XMR will work in English.