Audio mixer and ProRes: Dropped frames

[Bob Zelin]

No offense but –
you are thinking in terms of “magic and voodoo” if you think that changing your audio mixer is causing a dropped frame error. It’s not. I don’t care what you have observed.

Although I am not a big G-Tech fan, you have a VERY FAST disk drive array. I advise you to go to the AJA Utilities folder and run AJA System Test on your G-Speed XL 12 bay array. It’s probably insanely fast – certainly faster than the 18Mb/sec required to do 720p 59.94 Pro Res that you are trying to do. But certainly RUN AJA SYSTEM TEST right now (choose 1920×1080 with a 2 Gig file – this will tell you what your drive speed it – it’s probably hundreds of Mb/sec).

So, if your drive array is not defective (and you will tell by running AJA System Test), either your sequence is corrupt, or you have the worst static electricity problem in the world. I dont’ care if you you peak out your audio to severe distortion – it’s not going to affect your dropped frame issue.

I urge you to play back individual clips – move your mixer – any dropped frame errors – probably not. Now, CREATE A NEW SEQUENCE, and randomly drag in your clips into this NEW sequence. I bet it plays back when you move your mixer. If it does not, you in fact may have a severe static electricity problem (but highly doubtful).

What kind of mixer are you using ?

Bob Zelin

[Alan Okey]

[Bob Zelin] “What kind of mixer are you using ? “

Bob,

I think he’s talking about the software mixer panel tool in FCP. It’s conceivable that his G5 doesn’t have enough CPU grunt to simultaneously decode ProRes and perform real-time audio mixing during playback. In other words, it might be a question of CPU capacity rather than disk badwidth. After all, the G5 isn’t supposed to be fast enough to encode ProRes during live video capture, so it might be related…

[Alan Okey]

D’OH! I just reread the OP’s post and he is indeed using a Mac Pro, not a G5. So much for that theory…

[Matt Larson]

Bob, as the poster below correctly guessed it is FCP’s audio mixer that seems to cause the dropped frames. You may be right about the static electricity problem though: Now that’s it’s winter here in Wisconsin I get a wicked shock every time I touch my Mac Book Pro. I suspect you are right however, that is not causing my Mac Pro to drop frames!

I actually have had this problem for a while. I did an erase and install when upgrading to Leopard a few months ago but that had no effect on this playback glitch.

2 x3Ghz Quad MacPro
9 GB RAM
Mac OS X 10.5.5
QT 7.5.5
FCP 6.0.5
AJA Kona 3 (6.0.1 drivers)
G-Speed XL 12 RAID

[Matt Larson]

And yes the G-Tech drives are very fast. READ speeds in the 300MB range and writes faster than that. I have been happy with the drives (had them for just over a year) and their support staff is almost AJA-like!

2 x3Ghz Quad MacPro
9 GB RAM
Mac OS X 10.5.5
QT 7.5.5
FCP 6.0.5
AJA Kona 3 (6.0.1 drivers)
G-Speed XL 12 RAID

[Todd Dalton]

Hi!

I’m running a similar system (in fact my Sonnet raid’s prob not as fast). ‘Fraid to say that I’ve never experienced dropped frames with either an external usb mixer or dragging the software sliders. How many realtime tracks are you generally trying to do? I don’t use over 8 (more of a legacy of my editing experience than anything)….

Or keep trashing your settings? 🙂

Todd.

[Gary Adcock]

[Matt Larson] “2 x3Ghz Quad MacPro 9 GB RAM “

FIrst of this sounds as if there is something causing the CPU flush memory.

second- this RAM config sounds fishy – I am guess 4-2G sticks and 2-512’s

I have found randomized annoying issues with oddball RAM configs – try pulling the smallest pair.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

Inside look at the IoHD
https://library.creativecow.net/articles/adcock_gary/AJAIOHD.php

[Tom Daigon]

Im having the same exact problems with no mismatched memory and the same CPU and AJA setup. Any follow up?

[Tom Daigon]

Update: There seems to be an indication that the latest release of FX Factory broke the audio mixer tool in FCP. Several folks have reported deleting FXF and the mixer functions again. It has been reported to Noise Industries.

[Matt Larson]

Did they release a new version that fixes it? I haven’t had a chance to check this out, but I hope you are right about the fix.

2 x3Ghz Quad MacPro
9 GB RAM
Mac OS X 10.5.5
QT 7.5.5
FCP 6.0.5
AJA Kona 3 (6.0.1 drivers)
G-Speed XL 12 RAID