View Full Version : G4 Upgrade doesn't allow MPEG video at 2MB/s

08-27-2001, 01:52 AM
I just recently got an XLR7 MACh Speed G4Z Zif upgrade card (500 MHz) for my Biege G3 minitower and I have to say I've been happy it except for one tiny detail...

The computer does NOT seem to run MPEG's that were encoded with video streams at 2000kbits/s smoothly at first. These QuickTimes (MPEG videos) were made with the free MegaPeg LE plug-in that shipped with Premiere 5.0 years back.

When I open these files from my SCSI hard drive or Jaz drive, they jitter at first and the video usually smooths out.

Funny thing is that I retested my system with the old G3 (266 MHz) card and it runs the same MPEG Quicktime videos fine!

I've tried zapping the system P-RAM and that seems to do nothing... Adjusting the cache speed on the G4 does nothing either... Anybody have any ideas?

08-27-2001, 07:24 AM
My guess is that the G4 can play the video back faster than the G3, but then the G4 runs up against the slower bus of the Gossamer board (vs. the Sawtooth).

I've found that on my old systems they can play back video at upto around 5MB/s fine - as long as it is uncompressed. Tossing in some compression gives me much higher peak FPS, but it varies - from say 15 to 25 - (without compress I would get a 20FPS constant - for example).

Some things you can check to help your playback -
Set your DISK CACHE to 1MB or less
Turn off ALL unessential extensions
Turn off VM (if on)
Turn ON VM (if off)

I'm sure I forgot something.
What OS are you running?

Life in the fast lane leads to:
The Resteraunt At The End Of The Universe

08-27-2001, 12:10 PM
I'm running Mac OS 8.6 and have plenty of system RAM (416 MB) and I don't think those are the problem.

I'll try what you suggested with the system extensions and disk, but I didn't change any of that when I experimented with the old G3 266 processor and it worked perfectly... (Still, I like the performance of the new G4 ,particularly in Photoshop and Painter 6, and probably will NOT swap the old processor back in again.)

I have a feeling it may be the system bus.

Another thing -- the problem with MegaPEG LE disappears when I reset the video rate below 2MB/s, but funny how this was never an issue with the old processor.. >Sigh< Ah well, I'm probably not gonna get another hardware upgrade until I buy another computer.

08-27-2001, 07:40 PM
do you have your video set to millions or thousands of colors? (In other words, 24-bit versus 16-bit?)

also....are you running with "write-thru" enabled or disabled in the MAChSpeed Control control panel? (Default setting for that machine should be "off," but you may want to toggle it either way).

these are just long-range shots in the dark. They may not do anything.