[vlc] Re: Re : Hardware acceleration under OS X

[Derk-Jan Hartman]

On woensdag, apr 23, 2003, at 19:18 Europe/Amsterdam, Godefroy Troude 
wrote:
> Reading you answer (thanks for giving it so quick !) I think my 
> question
> wasn't precise enough.
>
> I just tested the playing of DVD-video with VLC in a big french shop 
> (BHV)
> where there was some PowerBook G4 in demonstration. I only could test 
> the
> PowerBook G4 867MHz with a DVD-video that I know well (Avengers, 1968,
> season 6, volume 1 - Universal 2002). There was almost enough power to 
> play
> correctly the DVD-video: there was still some dropped frame. So, I 
> thought
> that PERHAPS on a PowerBook G4 1GHz there would be enough power. But I 
> want
> to be sure of that !

A powerbook that powerful shouldn't drop any frames whatsoever.
I can almost play DVD's on my G4/400 without dropping frames. Anyways, 
the next releases are expected to increase speed considerably, 
especially with MPEG2 and audio decoding (which atm can be very 
intensive, especially with Dobly Digital sound like with dvd's that 
needs to be resampled for normal soundoutput on a powerbook).

> Then, I read on the FAQ that "VLC doesn't support the ATI DVD hardware
> decoding" and I asked myself the exact meaning of this sentence, that I
> still haven't understood after your answer (sorry). Is it:
> 1) VLC doesn't support ANY DVD hardware decoding
Correct
> 2) VLC support ANY OTHER hardware decoding than ATI

> Just a few words about hardware acceleration, because I have not the 
> same
> point of view: I agree that on a PowerBook G4 1GHz the hardware 
> acceleration
> is perhaps less important than on my iBook G3 500MHz, but this hardware
> acceleration is more reliable (because it is no dependant of other 
> process
> running on the machine), and I think also that hardware acceleration 
> will be
> power savy instead of intensive computer power decoding.

There is a big difference between hardware decoding (not supported) and 
video acceleration.
Video acceleration is supported trough the OS (which support and 
accelerates all the graphics cards from NVidia and the cards from ATI 
(Radeon and above).
Then there is a 3rd form of acceleration, called Altivec. This is an 
extra chipset on G4 processors that takes care of calculations that 
occur often in Multimedia applications. You can roughly compare Altivec 
to MMX (on intel CPU's) but it's way more advanced. VLC benefits a lot 
from this type of acceleration.

We can't say a thing about Video acceleration. This is all done by 
apple, and we have no idea of it's quality and workings on the various 
types of machines.

> In attachment (if it could interest you) a review of the problems I 
> found on
> the OS X Apple DVD player (versus OS 9 Apple DVD player). I'm french 
> and I
> translated it in english in the beggining of the text, but I didn't
> translated the last part because the Apple discussion forum didn't 
> allow so
> much text and anyway I must be shorter.

You need to understand that there is a substantial difference in how 
OS9 applications and how OSX applications run. OS9 applications used to 
be able to 'take' the entire CPU and use it completely for one task 
(playing your DVD).
In OSX this is no longer possible. OSX is a System that always reserves 
resources for other tasks that might be necessary or require attention.

Although most of the problems you describe in this document indicate it 
are problems with the mpeg2 decoder in macosx.

DJ

>> De : Derk-Jan Hartman <d.hartman at student.utwente.nl>
>> À : vlc at videolan.org
>> Cc : "Godefroy Troude" <godefroy.troude at wanadoodata.com>
>> Objet : Re: [vlc] Hardware acceleration under OS X
>> Date : Mer 23 avr 2003 18:03
>>
>> The OS takes care of graphics acceleration. We just give the OS our
>> graphics and it displays it.
>> The OS takes advantage of many of the hardware accelerations the
>> graphics cards supply.
>>
>> With the old Powerbooks, there was a problem that the CPU couldn't
>> DECODE the DVD fast enough. It therefore had an extra DVD decoder 
>> card.
>> This card was used by DVD player <= 2.0
>> Since OSX was released, apple dropped support for this particular 
>> card,
>> with that making that old Powerbook once again incapable of watching
>> DVD's. You are talking about way faster computers, which are probably
>> about 4-6 times as fast as the Powerbook discussed in the FAQ. The new
>> Macs don't need such a card, because they can handle decoding all by
>> itself (and do something in the background at the same time ;).
>>
>> Just remember that a G4  1Ghz is always faster then a G3 1Ghz CPU.
>> The Graphics Cards are less important then you make them out to be.
>> When you want to run all the latest games, then you need to take a 
>> look
>> at what kind of graphicscard you want.
>>> I read in your FAQ: "3.1.1. Does VLC support the ATI DVD hardware
>>> acceleration cards? -> Currently it does not. We would be glad to
>>> support
>>> them, but we lack technical information on them."
>>>
>>> Is hardware acceleration supported with new PowerBooks with Nvidia
>>> cards ?
>>> In example 12 and 17 inches PowerBooks ? I'm planning to buy a new
>>> Powerbook or iBook and hardware acceleration in VLC will be a big
>>> element of
>>> my choice ! OS X Apple DVD player is really uggly with many DVD (OS 9
>>> was
>>> better).
---
Videolan - VLC media player
Derk-Jan Hartman (thedj at users.sourceforge.net)
Co-Developer of the MacOS X port of vlc
http://www.videolan.org/vlc

-- 
This is the vlc mailing-list, see http://www.videolan.org/vlc/
To unsubscribe, please read http://www.videolan.org/support/lists.html
If you are in trouble, please contact <postmaster at videolan.org>