Thanks megaspaz, it's much better since I enabled dma.

I read through this (and a few other related topics) because of jerky DVD video playback.
I tried several of megaspaz's tips, and things are a bit better - the picture is clearer (no horizontal lines) but it still freezes every second or so.

I tried -a1 -c1 /dev/dvd, and got:
then hdparm -a1 /dev/dvd, but still get:
Does this mean that 'readahead' is not being enabled?

The overall system specs are:
AMD K6-2 450MHz o/ced to 500MHz
512MB RAM
ATi Radeon 7500 with 3D Acc enabled
Toshiba DVD-ROM SD-M1202 with DMA enabled.

I know it's nothing close to modern, but it played DVDs OK when running Windows 98, had an 8MB graphics card and was at 450MHz.

Did you enable DMA with the "-d" option?

Yes, but DMA is already enabled (through YaST) from boot up on all drives.

I now get readahead enabled, and the picture quality is better, that is, no ghosting, but it is still jerky.

before running Xine, in a terminal I type:
hdparm -a1 -b1 -c1 -d1 /dev/dvd

This ensures that readahead, 32 bit IO support, DMA and something else (not sure what the "bus state" is...)

One other question, how do I set readahead to be enabled by default at boot up?
What file do I need to edit?

I've been following this thread because I can't set DMA for my new DVD ROM /dev/hdc. I also have an /dev/hdd which is a CDRW and am running SuSE 9.3. Command line konsole outputs for the commands outlined in the thread follow:

fragos@linux:~> su
Password:
linux:/home/fragos # hdparm -d1 /dev/hdc

/dev/hdc:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)
linux:/home/fragos # hdparm -d1 /dev/hdd

/dev/hdd:
setting using_dma to 1 (on)
using_dma = 1 (on)
linux:/home/fragos #

linux:/home/fragos # hdparm -I /dev/hdc

/dev/hdc:

ATAPI CD-ROM, with removable media
Model Number: LITE-ON DVD SOHD-16P9S
Serial Number:
Firmware Revision: FS07
Standards:
Used: ATAPI for CD-ROMs, SFF-8020i, r2.5
Supported: CD-ROM ATAPI-2
Configuration:
DRQ response: 50us.
Packet size: 12 bytes
Capabilities:
LBA, IORDY(cannot be disabled)
DMA: mdma0 mdma1 mdma2 udma0 udma1 *udma2
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=227ns IORDY flow control=120ns
linux:/home/fragos #

linux:/home/fragos # hdparm -tT /dev/hdc

/dev/hdc:
Timing cached reads: 704 MB in 2.00 seconds = 351.53 MB/sec
Timing buffered disk reads: 4 MB in 3.70 seconds = 1.08 MB/sec
linux:/home/fragos #

linux:/home/fragos # hdparm -v /dev/hdc

/dev/hdc:
IO_support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 0 (off)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 256 (on)
HDIO_GETGEO failed: Invalid argument
linux:/home/fragos #

Well I'm out of ideas. I did have jerky playback once after I fried my power supply. Never solved it but I didn't know about hdparm back then... So I guess I just don't know.

One the command below is run, is it set forever as such or is there a file I will need to edit to make the change permanent

you need to add it to a script, reboot will reset the change

If you use YaST to turn DMA on it will be a permanent change. For me, I find command line great for diagnosis but since I often have to ask where to make things permanent -- I use YaST for most configuration tasks. By the way, my problem turned out to be two fold. First the replacement drive I bought had a hardware problem. The second was a configuration issue which I solved by using mplayer and kmplayer. Kmplayer sets up xine and mplayer with an easy to use GUI. I'm back to my older DVD-ROM and all works well.

Oh yeah I figured that YaST would solve all