Dropped frames at playback in FCP 5.1 on Mac G5 Quad

[Jerry Hofmann]

Try mixing the audio down. The more real time you do, the faster the drives need to be. Most dropped frames are due to the drives not being able to keep up with the demand. Mixing down the tracks and rendering unrendered effects will ease the demand… or faster drives of course.

Keep all the media on that G-Raid too. It’s your best shot at not dropping frames.

Jerry

[Shane Ross]

What format of video are you working with? Remember, the more tracks of audio and video you add (called “streams”) the more taxing it is on the throughput of the drive. It isn’t the speed of the computer you are battling here, it is the speed of the drive. If this is DV footage, you are pushing the limit as it can do 7 streams of DV25:

https://www.g-technology.com/Products/G-RAID.cfm

Shane

Littlefrog Post
http://www.lfhd.net

[Khashyar Darvich]

Hi Jerry,

Thank you for your feedback.

So, you believe that a Quad G5 with 4.5 GB RAM would not be fast enough to handle 12 audio tracks and 6 video tracks?

At the time of the dropped frame, there were only 4 audio tracks (connected to the two video clips) at that point in the time line.

To mix down the audio tracks, can I change the “User Preferences” to lower the “Real-time Audio Mixing” setting to less than the default 8 tracks? My understanding is that tracks above the set number will be rendered.

Since I need to export all of the seperate audio files to be mixed in Pro Tools, I don’t want to mix down tracks right now.

Yes, all of my video and audio files are on the G-Raid (aside from some photos and music files, which are on a new secondary internal Hard Drive.

Thanks for helping me understand what the issue is.

Khashyar

[Khashyar Darvich]

Thank you, Shane.

I am working with (mini)DV.

By streams, do you mean all video and aiduo tracks combined?

The reason why I like to work with several layers is so that I can layer clips build image sequences via layers.

If I have to limit the number of tracks I am using, then I might use more L-cuts in my edits so that I need fewer video tracks.

I appreciate your feedback,

Khashyar

[Khashyar Darvich]

Hi Shane…

I see that the G-Raid specs state that it can work with 7 DV video streams…

However, at the time of the dropped frame, there were only 2 video tracks present on the timeline.

I know that audio tracks take fewer resources than video tracks, but I think that I will try to reduce the number of video tracks to 5 and see if this resolves the issue….

Khashyar

[Shane Ross]

Streams refers to video…not video and audio combined.

Hmmm…seems odd that it would be dropping frames at 2 or even 5 streams. How is it connected to the system? Firewire 400 or 800? And is there any other device connected to the system as well via firewire? Because the G5, as stupid as it is, has only ONE firewire bus for all the firewire ports, FW800 included. So something else on the bus might slow down everything.

If you have other devices it would be wise to invest in a PCIe firewire card to get you more ports and buses.

Shane

Littlefrog Post
http://www.lfhd.net

[Khashyar Darvich]

Thanks, Shane.

The G-Raid drive is connect through a firewire 800 port.

Nothing is connected (or daisy-chained) to the G-Raid, although the firewire hub on the 30′ cinema screen is connected to the second G5 firewire port.

Connected to the monitor’s firewire hub is one Sony DSR-25 dv deck, although it is not on or being used when the dropped frames occur.

I read on the G-Tech website that the G-Raid (when connected via a firewire 800 port), “saturates the FireWire bus bandwidth and provides a minimum sustained data transfer rate of 75 MB/second.”

If a DV video track is about 4mb/sec, and an audio track about 0.2 mb/sec, then if I had 6 simultaneous video tracks (24 mb/sec) and 12 simultaneous audio tracks (2.4 mb/sec), then that would not come close to the 75 mb/sec that G-tech says the G-Raid can handle.

Khashyar

[Jeremy Garchow]

Do what Jerry says and mixdown your audio. Mixing down does not effect anything on your final output, all it does it take all of your tracks and essentially renders them to one temporary file for ease of playback. It’s not like Avid. You will be able to export to Pro Tools when the time comes. It does not combine the tracks or anything like that. Select all in your timeline and then go to Sequence > Render Only > Mixdown. Also, make sure that your are rendering all effects, even the ones marked ‘full’. Go to the Sequence > Render Selection and Sequence > Render All menus and make sure there’s a check mark next to every option in there. This will assure that all of your full time rt effects get rendered.

The speed of your computer is one thing, but the faster the drives, the faster your rt. How full is your GRAID? The more full it gets, the slower it gets.

Jeremy

[Khashyar Darvich]

Thanks Jeremy,

Actually, not all of the rendered options were checked, so perhaps not everything was getting rendered, although I would always choose the “Render All – Both” option. this may have affected playback…

thanks for clarifying the audio mix down feature… I will certainly do that (and understand that it will not combine audio tracks and leaves them in tact)… But, my question is: since each audio track requires about 0.2 mb/sec of hard drive resources, why would there be a need to mix down audio tracks if your hard drive can handle 75 mb/sec? Pro Tools, for example, can manage 20+ audio tracks without a problem. I understand that video requires more hard drive streaming resources, but audio tracks are much smaller in file sizes than viedeo tracks are…

However, I will definitely try to mix down the audio tracks on my 2 hour timeline 🙂

I think that first, I will try to see if I keep dropping frames after I reduce the video tracks from 6 to 5 (I’m half-way finished with that), as well as render with all of the items checks.

I appreciate your feedback and thoughts,

Khashyar

[Jeremy Garchow]

Audio mixdown will go quick. How full are your drives?