[Preston] DVD playing

[Andrew King]

Dougie Nisbet wrote:

>I've paid zero interest in this until today when I replaced a knackered CDROM 
>with a DVD rewriter. It's a whole new world. After working out that DVDs are 
>encrypted (well I didn't know) I managed to find some software that would 
>allow xine to play them. So far this amounts this only amounts to the opening 
>credits of Crouching Tiger Hidden Dragon, but it's a start. 'xine-check' 
>tells me I should run hdparm -d1 to switch on DMA for my DVD (which is 
>secondary master /dev/hdc) but when I try that I get 
>
>root at tbird2:~# hdparm -d1 /dev/hdc
>
>/dev/hdc:
> setting using_dma to 1 (on)
> HDIO_SET_DMA failed: Operation not permitted
> using_dma    =  0 (off)
>
>It says that about any drive so perhaps I need to install something or tweak 
>the kernel? I read some dire stuff about hdparm recently in the debian user 
>newsgroup so I'm a bit cautious - that usually means I hesitate for a second 
>or two, then press <return> anyway. 
>
>I'm running kernel 2.4.22 Debian testing on a KT7 mobo with Athlon 850. 
>  
>
I've had Xine playing really badly (about 2fps) - but still at least 
playing, I guess, on a dual-pentium II 350 debian / linux-2.6 system, 
but with a crap graphics card.  That it plays at all has to be a good 
start I think :)

Not sure whether that can in theory run okay or not - although I'd had 
guessed so.

Does anyone here have a clue what all the different things are in 
XFree86 that make it go faster, how to enable them, and which actually 
make a difference?  Here's what I managed to figure out last time I had 
a crack at this last year:

- Have lots of memory (am ok with this, and am guessing that 256MB 
should be enough just for dvd playback).  Done this.
- Use the correct XFree86 driver, rather than just VESA?
- Enable MTRR (compile into kernel, then check with cat /proc/mtrr).
- Enable DMA with hdparm.  Done this.
- Enable XVideo (this is one of the unknown ones - I can't find any 
docs, manpage, or anything about it, and haven't exactly found the time 
to go looking for source code yet)
- Enable YUV overlays (no idea!)
- Enable DRI/DRM.

Am also thinking that enabling pre-emptible kernel and dual processor 
support and on 2.6 would help.  Have done this.

I think there could be a Making-XFree86-Efficient-HOWTO on this kind of 
thing.  Maybe even a Making-XFree86-As-Efficient-As-Windows-HOWTO, 
even!  (Not a windows user by any means though...).

Andrew