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Jittery video in AVID Media Composer 6.0.1

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Henry Barrial
Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 12:48:52 am

We've been editing a feature film on AVID 6.0.1.

The video has stopped playing back smoothly. It's very jittery, seemingly losing one or two frames for every frame played. The audio plays back consistently and slips out of sync. I've cleared out my system drive to have enough free space as it used to when I began editing, so that can't be the issue. I've made my computer as fast as it can be. Is it the project that has become too large? Should I start a new project and paste my old timeline in there like I would in the old FCP? I am playing back the timeline in yellow/green or even yellow and I still get the jitter. Should I upgrade to 6.5? Any advice?


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Michael Phillips
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 1:12:22 am

What are your system specs? OS, etc. What codec/data rate are you using? what kind of drives? What is the connection to the computer? How full are the drives? Do all clips play that way, or just those clips in that part of the timeline?

Michael


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Henry Barrial
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 3:29:25 am

Meant to include these. These are specs for my jittery computer:

Processor 2 x 2.8 GHz Quad-Core Intel Xeon
Memory 4 GB 800 MHz DDR2 FB-DIMM
Graphics ATI Radeon HD 2600 XT 256 MB
Software Mac OS X Lion 10.7.5 (11G63)


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Henry Barrial
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 5:54:10 am

Processor 2 x 2.8 GHz Quad-Core Intel Xeon
Memory 4 GB 800 MHz DDR2 FB-DIMM
Graphics ATI Radeon HD 2600 XT 256 MB

I am editing natively in PRORES 444 through AMA linking. The AMA linking has worked fine for months.

Drive is an 8 TB G Raid via eSATA 3Gbit

6.8 TB of the 8TB are used up on the drive.

All clips start to play well then they devolve into jitter. Some sections don't jitter if I play in a small window. But everything eventually jitters especially when I'm in full screen playback.

I will play back a portion of the timeline and I can actually see the red marks being added in realtime on the timeline as the "cursor" plays through the sequence. My drive sounds like it's working extra hard. Perhaps I should relieve it of some of its extra material. Clean house a bit and see if it's the drive. I'll try that and report back. Thanks!


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Henry Barrial
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 6:16:35 am

Was able to lose about 2TB of MXF backups of media on my 8Tb gRaid. MC6 playing back better, but everything with multiple layers of effects stumbles into that jitter. I feel like I'm getting closer to an answer. I could probably find another 3-500 gigs to lose. Should I do that? Glad it's running better though. The drive actually sounds happier.


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James Beattie
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 10:30:23 am

I anticipate the AMA linking is your pain point. I don't know if you are using internal or external drives, but I bet some of the issue is AMA.

AMA is great for quick review and working with media, but once you start compositing and playing back multiple layers it strains the architechture.

I would recommend transcoding your material into DNxHD to continue working with it. I am not sure of your online strategy, but with dropping frames, your offline is starting to cause headaches.

If you click on your sequence, go under clip and choose transocde, then transcode to DNXHD (many options to choose from, you can go to DNx36, which will be a smaller file, but it is not a finishing file format). This will convert your filed into a lighter codec that Avid is optimized for, then you will notice an immediate improvement.

Again, if you are going to online later, you can relink your final sequence later to the higher resolution files once your edit is completed. Avid 6.5 is much better at this than 6.0.

A lot of folks are running into this as their AMA timelines get more complex. AMA in this instance uses Quicktime to be the engine that plays back in the background, which isn't as efficient as Avid's playback engine. You can also simply render the files (like you would do if FCP had these issues). You can add an effect to the top track, and render it. Even if you create a simple PIP that is fullscreeen. This will create a new file that is ready to trim.

The best option is to transcode, it will give you the most flexibility when adjusting edits and you won't be rendering constantly.

James Beattie
ACSR Elite/Avid ACI, Apple Certified Technician

Consulting for Workflow and Digital Technologies at Comprehensive Technical Group


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Michael Phillips
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 12:12:04 pm

James is pointing to one of the fundamental issues is AMA. While Avid marketing will list all the advantages of AMA, it is light on the more day to day realities of using AMA in all situations. You are also somewhat constrained by codec data rate and drive and how full it is combined with number of layers of video being combined for playback in real time.

AMA to ProRes using a plug-in architecture that provides a decoder as a host - in this case, QuickTimes. That is great as it provides access to many codec types out there not natively supported, but adds additional process steps to the decode and playback of the content. All of this adds up to a less performant experience to an Avid natve codec being managed by Avid MediaFiles structure wrapped in MXF.

V6 added ProRes as a native codec when managed by MXF in MediaFiles folder but that was a result of a fast import. v6.5 does bring you the ability to consolidate ProRes to MXF wrapped ProRes which is faster than an import and keeps the native Prores codec.

But, the next thing you are running into is high data rate codec attempting to play layers and such on a drive that is getting full and only has so much sustain data rate power. All of this adds up to performance hits.

Typically, when dealing with long form productions using ProRes 444, it is best to transcode to a lower data rate for editorial such as DNxHD 36, which is great quality, lots of storage, and great performance. When done, a relink to the hi-rez 444 files while in a 444 project type will be the way to go. If the 444 were recorded with LogC, then I usually make dailies in a product like Resolve, Cortex, or others system that can apply LUT to Rec.709 beforehand for editorial.

In your scenario, a consolidate may being a bit better performance as it removes QuickTime decode from the pipeline. But then you still have to deal with drive performance, full drive, and limited connection for hi bandwidth multi-layer playback.

If you are getting near the end of your edit, you can always transcode just the sequence to DNxHD with handles, and deal with new material accordingly as a way to minimize the amount of transcode you need to do at this phase of the process.

And while on the topic, you can read this whitepaper which touches on a lot of the offline/online workflow when working with ProRes and other digital cinema camera type files:

http://www.avid.com/static/resources/documents/whitepapers/digital_camera/d...

Avid doesn't make it easy to find unless you know that you're looking for it. Would be nice to link it from the AMA and RED landing pages...


Michael


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Henry Barrial
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 8:40:10 pm

This is what I was afraid of. I was warned about AMA but I just liked the thought of editing native. No truth in advertising on that one. In any case, thanks for the white paper. I'll see what I do after I read that.
Appreciate the help.


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James Beattie
Re: Jittery video in AVID Media Composer 6.0.1
on Mar 26, 2013 at 1:27:00 am

In the timeline area, are you getting colors showing up. Red for dropped frames, but usually before it drops, it shows yellow (processor overloaded) or Blue (drives can't keep up).

It sounds like it is drive related, without knowing the details.

James Beattie
ACSR Elite/Avid ACI, Apple Certified Technician

Consulting for Workflow and Digital Technologies at Comprehensive Technical Group


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