After exporting a video (no audio) Clip using Avid, the exported Clip (size 32 Kb) plays in a jerky fashion - plays for a second or two - then stops - then continues and so on.  The Clip was exported as a QuickTime movie in DV-PAL at 25 f.p.s. with 720x576 dimensions - single field.

I've tried altering Compression from maximum to minimum but this has no effect whatsoever.  I've tried altering the field to 'Odd first' - no effect.

Very frustrating!!  I'd be eternally grateful to anyone who can solve this problem for me.

Hi,

What is your goal for the file (DVD? Web? Something else?)?

good luck,
Carl

 It is good to be in touch with you again!  Sorry for the delay in replying - I had to go out for lunch.

The file is to be uploaded to, and sold by, a firm called Revostock (www.revostock.com) who sell copright free .mov files over the net and from whom I have bought many files in the past.  They seem to set high standards and I have been accepted by them, in principle, as one of their producers.  The file in question that plays jerkily is my first attempt to get a satisfactory file to them, but the play is faulty not only at my end, but also when they play it at their end.

I undersatnd that QuickTime are bringing out a better player, but I don't suppose that will make any difference.  Does that answer your question? - Michael

Hi Michael,

No worries about the delay, I hope lunch was good. 

Unfortunately, I'm afraid I don't have any ideas for you.  I was hoping you were trying to make a DVD or a web clip, in which case it wouldn't necessarily be a problem that the movie wouldn't play, as that's an intermediary step.

Hopefully somebody will chime in with some ideas.  Anything I'd say at this point would be guessing.

good luck,
Carl

 Even some guesses that I could experiment with might be helpful! - Michael  I've already tried exporting as an MPEG-4 file and that plays smoothly but that is no use to them.  Is there a prog. thatbwould convert MPEG-4 to .mov - might be worth a try.

What is the running time of the video you are trying to export/upload?

You mentioned the clip was 32Kb in size. At PAL DV resolution (25 megabits / second) even one second of footage would be larger than that. (Approx 3 megabytes).

 The Clip is 9s long!!  What's going on here?

You mentioned that you've tried changing the compression settings from maximum to minimum etc...

Can I assume then that in the export options you are choosing a custom quicktime export, and not exporting "same as source" ?

What is your project type? 25i? 25p?

Try exporting "same as source" with lower-field first dominance (which is the standard for PAL DV footage).

 Yes, I'm exporting custom quicktime and I've tried compression from max to min. and not "same as source"

"What is your project type? 25i? 25p?"  I don't understand this question or how to find out the answer.  Unfotunately, I've got to go out again now but will be in touch later and in meantime will try lower field first dominance, which I haven't actually tried so far

I think that you're putting the cart before the horse a little here.  Your playback is jerky probably because you have bandwidth issues.  Wrong field dominance isn't going to exhibit the problem that you describe in your first post.  The company's other material isn't skipping, so it obviously doesn't have the issues that you have.

As a first step I would ask them what file format they need, what codec they expect, and the stream rate or compression factor that they use.  They must have specifications that they require.  Meet them, and I'll be very surprised if your problems don't immediately vanish.

And no need to apologise to us for going away again.  It's not us with the problem.  Only you know how urgent it is.

Ahh, JWRL is onto something that escaped me. I took the original post to mean jerky playback on the exported file from Avid, prior to uploading it, rather than jerky or lag-riddled playback from the online provider.

To help us out, clarify whether the jerky playback is local (on your machine via the exported file) or remote (streamed from the online provider).

I suspect that it's the actual quicktime file.

I've just re-read the entire thread.  There are a few points that are immediately obvious.

malefunktion:

You mentioned the clip was 32Kb in size. At PAL DV resolution (25 megabits / second) even one second of footage would be larger than that.

OSTrust:

The Clip is 9s long!!  What's going on here?

PAL DV is roughly 4 minutes per gigabyte.  At that rate your 9 second file should be around 37.5 Mbytes.  Obviously you are compressing it very heavily if you've got it down to 32 K.  At these rates the speed at which the material comes off disc is less of an issue than the amount of work the CPU does to expand it.  So extremely high compression rates may be a factor.

OSTrust:

"What is your project type? 25i? 25p?"  I don't understand this question or how to find out the answer.

Then with respect you may need more help than can really be provided here.  Knowledge of interlaced and progressive media is so fundamental to understanding video that it's hard to imagine how you've got so far without having it.  It's the equivalent of an artist not knowing the fundamentals of colour mixing.

We may be able to talk you through your immediate problem, but if you intend building a business doing this you need training.  What will happen when you hit your next brick wall?  Contact your local training bodies and see if you can do a course in television fundamentals  You don't need to be a qualified technician, but there is a minimum level of background knowledge that you absolutely have to have.

jwrl:

PAL DV is roughly 4 minutes per gigabyte.  At that rate your 9 second file should be around 37.5 Mbytes.

Hi,

Unless he's confusing kilobytes for megabytes and the file is actually 32 Mb, in which case I'd imagine a computer built to run Xpress Pro 4.6 with 1GB of RAM might have trouble playing it back.  We'll see.

adios,

Carl

If it is a 32MB DV-compliant file I doubt a system capable of even executing Xpress Pro would have trouble playing back such a file.

If the playback through quicktime is problematic, it could be a quicktime issue. Quicktime does make use of videocard hardware to accelerate (help along) playback. I notice that the system in question is using a Radeon 9200SE card (very outdated and possibly not even AGP).

If the card has multi-display output capabilties, it may be causing quicktime no end of problems (I've seen this with some Nvidia cards and it relates to quicktime's implementation of Direct3D acceleration).

There really are a number of potential areas to investigate, but I'm with JWRL on the matter of not being able to even identify what 'type' of project is even being worked on. Xpress is 'pro' software and naturally implies that those using it have a basic understanding of certain technical aspects such as field dominance, formats and compression (to an extent).

To echo JWRL, we'll try to help out, but a computer system (notably an unqualified system) is a complex setup before you even throw into the hat editing and video technologies along with operating system software and other complexities.

Thank you everyone for your suggestions so far.  I'll spend some time sorting these out and then be back to you again - Michael