5.1. xvinfo returns "no adaptors
present"
Make sure you are running XFree86 4.1 or above. You can find
out your version of XFree86 by typing X
-version at the command prompt.
Use an appropriate driver for your video card. Some Linux
distributions default to using the generic XFree86 VESA driver instead
of the specific driver for your video card. You need to use the
hardware-specific driver for your card in order to get hardware
overlay support.
ATI users should try downloading the improved ATI XFree86
drivers from the GATOS home page, or from the
official ATI
Linux support page.
NVidia users should try downloading the official NVidia
Linux drivers for their video card.
Sometimes upgrading XFree86 can provide you with an
improved driver that has hardware overlay support, but such an upgrade is
beyond the scope of this HOWTO.
5.2. xvinfo works but overlay output is
garbled
Problems with garbled or missing overlay output usually mean
that you don't have enough video RAM to hold both the regular desktop
display and the video overlay display at once. Typically you need twice
as much video RAM as normal at a given video resolution in order to use
hardware video overlay. In some cases you may even need 3 to 5 times more
RAM because of internal buffering in the video card.
The only easy way to lower your video RAM requirements is to
switch to a lower video resolution while playing videos.
You can tell that DMA is broken if using the command
hdparm -d1 on your DVD drive returns a message like the
following:
# hdparm -d1 /dev/hda
/dev/hda:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)
|
The only way to fix this problem is to compile a kernel with DMA support
for your particular chipset. It is beyond the scope of this HOWTO to
explain how to compile a kernel, but the steps which are particularly
relevant to DMA support are as follows:
Download a recent kernel so that
you have the greatest possible chance of DMA being supported on your
chipset.
Unpack your kernel and type make
xconfig
in the kernel build directory. Under "ATA/IDE/MFM/RLL support",
select "IDE, ATA, and ATAPI Block devices" and enable
"Generic PCI bus-master DMA support" and "Use DMA by
default when available".
On the same page there are several dozen chipset-specific DMA
drivers that continue downward for several screens. Find and select one
relevant to your chipset, if there are any. For example if you have
an AMD Athlon based VIA chipset, enable the "VIA82CXXX chipset
support" item.
For more information on compiling kernels, see the Kernel HOWTO as
well as the Linux
Ultra-DMA Mini-Howto.
5.4. Video playback is choppy
On a fast enough computer (say, over 1 GHz), choppy video
playback usually means that your overlay support or DMA support is
misconfigured. See the previous troubleshooting items.
On a very slow computer (say, 0-500 MHz), there is nothing
you can do short of hardware upgrades to make DVD playback run well.
For borderline computers (anything in between), you can
gain a modest (~10%) performance boost by upgrading from kernel 2.2 to
kernel 2.4 and using an SSE-optimized player program like
MPlayer.
Finally, if all else fails, run MPlayer with the option
mplayer -framedrop to patch over occasional glitches
in video playback.
5.5. Sound playback is choppy
The most common cause of sound playback problems is from
sound cards that do not support 48 kHz audio playback. For people in
this category, I strongly suggest that you purchase a new sound card.
Even a cheap PCI sound card can give you a substantial upgrade in sound
quality for less than the cost of two DVDs.
Failing that, you can lighten the load on your sound playback
system by not using a sound daemon such as ESounD or aRts and playing
the DVD audio directly to the OSS driver. To do this with MPlayer, run
mplayer -ao=oss along with whatever other options
you normally use.
5.6. Out of region discs play back garbled
In the past, older versions of most of the programs
discussed here have had trouble decrypting out-of-region discs. The
result of a failed decryption looks like the colored video noise that
you see.
Upgrading to the newest available version of any of the
programs should solve this problem.
5.7. Out-of-region discs hang on playback
Watch the DVD drive's access light while the program is
hanging. Is the light still blinking in an access pattern? If it is (and
usually it will be), that means the program is still in the middle of
decrypting the disc.
Decrypting the DVD involves mounting a fairly
large-scale computational effort to recover the key. It is not at all
unusual for a computer to take five or even ten minutes to decrypt a
single DVD key.
In-region discs never have this problem because the DVD drive
firmware automatically decrypts discs that match with the drive's own
region.