Mpeg2Dec2 or Mpeg2Dec3?
 

I've been reading that Tom Barry's mpeg2dec2 is faster for Pentium 4 processors, but I see kwag's script useds Mark's Mpeg2Dec3.

Is there a quality or feature difference between these? I have a P4 so I'd like to take advantage of it.

Thanks

I guess a better question is does anyone use this option "idct=5"

example:
Mpeg2Source("D:\Projects\project.d2v",idct=5)

The documentation for Mpeg2Dec3 says this is faster for P4 machines. I notice Kwag doesn't use it even though he has a P4. I don't really understand this setting and am curious if there is a quality impact by using this and if anyone has actually noticed faster frameserving and overall reduced encode time with this option.

Hi audi2honda,

I hadn't paid attention to that :!:
I guess I'll have to run a clip with and without that option, to see how it impacts speed and/or quality :idea:

-kwag

Done :!:
Results are identical in both file size and speed. Did a 30 second clip, and there was no difference.

-kwag

what version of mpeg2dec3 do you have? a new version with optimized code was just released about a week ago.

Version 1.00, 5/20/2003.

Edit: The date is when I downloaded it. Do you have a newer version :?:

-kwag

Give this one a try. You have to set idct=5 in your .d2v file and in your .avs script after the mpegsource call like I put in that simple example above. Let me know if you notice any performance. I'm playing with it too.

http://forum.doom9.org/showthread.ph...ght=idct+speed

last from nic v1.08:
http://nic.dnsalias.com/

:wink:

Ok, same result with 1.08. No diff with or without "idct=5" :)

As: Mpeg2Source("F:\KPAX\VIDEO_TS\movie.d2v")
Or : Mpeg2Source("F:\KPAX\VIDEO_TS\movie.d2v", idct=5 )

-kwag

oh well worth a try :?

Maybe on a higher end P4 (2.4+Ghz) there's a difference. Mine is a poor 1.6Ghz CPU :roll:

-kwag

This is a bit off-topic, but just thought I'd add that there definetly IS a noticeable speed increase if you have a P4 processor and use "idct=5" in your .d2v while using MPEG2DEC2 in Avisynth 2.08. I guess MPEG2DEC3 must need a bit more optimizing. :wink:

-d&c

i'm going to try it now. Kwag did you put it in your .d2v file also?

No :!:, only in the .avs :roll:

-kwag

Just ran a short sampler encode with idct=4 vs idct=5 in Avinsynth 2.08 with MPEG2DEC2 to verify my previous statement :wink: :

time with idct=4 in .d2v was 3:25
time with idct=5 in .d2v was 3:05

that's with a P4 2.26Ghz, btw.

It's a pity if the same speed boost doesn't ring true for MPEG2DEC3.

-d&c

Then what about MPEG2DEC2 vs. MPEG2DEC3 comparison both on 2.52 :?:

-kwag

I'm running some tests with mpeg2dec3 and will have results in about 10 minutes. THen I'll use mpeg2dec2

I'm creating a new project file with DVD2AVI 1.77.3 to compare against the one I have, which was done with DVD2AVI 1.76.

-kwag

Well, I see no diff with my CPU. I just tested with DVD2AVI 1.77.3, and verified the project file. It's using SSE-2,MMX. Here's the line:
iDCT_Algorithm=5 (1:MMX 2:SSEMMX 3:FPU 4:REF 5:SSE2MMX)
Maybe my P(iss)4 CPU being 1.6Ghz, it's not good enough to see a difference :!:

-kwag

I don't see any difference either. I ran a few times and there was no difference between the plugins. I have a P4 1.8. I've got a 2.8ghz at work that I can try a few tests on tomorrow, but it seems the difference is negligable.

I'd try mpeg2dec2, but i'm not giving up AVS 2.5