Re: iBook and playing DVDs
On 10 May, this message from Rogério Brito echoed through cyberspace:
>
> Well, I'm not having luck getting my iBook 600MHz playing DVDs
> in a decent way.
I think you're quite lucky with what you get ;-)
> I have woody installed in this iBook and, with xine (0.9.8), I
> get a reasonable playback, with around 15% of dropped frames
> and with ugly interlaced frames. Enabling the onefield_xv
> deinterlace method works and makes the DVD more or less
> watchable, though during some stages, I can see artifacts on
> the image due to excessive frames being dropped.
This is probably as good as it gets right now. I don't think you can do
better without using the r128's hardware accelerated iDCT and MC.
> I can't get vlc 0.3.0 working well here, because there are
> issues with the sound (probably due to endianness problems,
> although I'm not really sure). I already tried telling vlc all
> different possibilities for endianness or signedness of the
> output, but I don't know if the menu is functional, as I saw
> little changes when I played with that option. Enabling the
> diagnostics seems to suggest that not all frames are played.
vlc has had sound problems for quite a while. Here's what Jack Howarth
said re. vlc's audio settings:
[quote]
> On my debian sid machine running benh's current kernel and
> alsa 0.9beta12 I was able to get audio working under alsa, esd and
> oss. You have to select 3, the 16 bit signed big endian output from
> the audio preference section for that to work. I notified Samuel
> Hocevar and he is going to try to do something about the default, 0,
> native endian code so that it picks up 16 bit big endian on ppc.
> The audio problems with bursts of static aren't ppc specific.
> There has been and still is a audio starvation problem in vlc
> but according to Sam no one has the guts and/or time to rip into
> that code yet.
[ end quote]
I haven't tried this myself.
> The output of mplayer shows the amount of time it spends
> decoding the frames, showing the frames and dealing with
> audio. I notice that the percentage of time it spends with
> video output is quite high in comparison to my Celeron 466MHz
> (I'll make further tests).
That's essentially because of MTRR on i386. I wouldn't know hard numbers
to compare, but at least subjectivly, MTRR helps a lot for the copy to
VRAM of the video out data.
> I tried installing Michel's XFree 4.2.0 binaries and they seem
> to make xine work better, dropping around 6 frames less than
> with woody's X 4.1.0.1.
>
> On the other hand, DRI (which, I heard, is supposed to enable
> DMA transfers to video) wasn't enabled with XFree 4.2.0
[snip]
Note that for DMA you need DRI, which needs large amounts of VRAM. So
you may only be able to use that in 16-bit mode. I'm usually running in
32-bit mode :(
> I have already tried many things that I could think of, but I
> am starting to think that the possibilities are almost
> exhausted. :-(
You've got it :-) No, there are a few things that still can be done:
- get ATI to open the specs for iDCT and MC in hardware. Won't happen
anytime soon.
- optimize a few of the more processor-intensive parts of the algorithms
with handcoded ASM. Good luck...
- use DMA: that should be doable with the right pieces of code.
Cheers
Michel
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