D90 files work in 720p30 Projects. Why? How? at DVinfo.net

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Old December 14th, 2008, 02:33 AM   #1
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Join Date: Feb 2003
Location: Las Vegas
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D90 files work in 720p30 Projects. Why? How?

I downloaded sample from D90.

The sample is 720p24 OpenDML JPEG with mono at 11.025kHz.

I import into iMovie HD 06 and it becomes AIC -- but now at 30fps. (Audio is now 48kHz Stereo which is fine.)

Here's the weird part, it plays fine in a a 720p30 project. No pitch change. No stuttering. I've never seen 24p converted to 30p with no issues! Where did the extra 6 frames per second come from?

So I import into FCP with no conversion and drop it into AIC and ProRes projects each of which is 720p30. Everything plays fine. These 24p clips play just like 720p30 clips play.

So I import into iMovie 08. It imports fine -- which is very strange because iM08 doesn't support 24p!. And, again the clip plays fine with other 720p30 clips.

Next, into an Avid Media Composer 720p30 Project where it played fine.

So either these files are labeled as 24p but really have 30 frames every second OR 720p24 clips play fine in 720p30 projects. Which could be possible, but I've never heard of this being the case. Of course, I suppose the 24p clips could be playing fast and yet I can't hear the pitch change. But, if this is true -- why can't 25p clips be played in 30p projects?

Anyone have any idea what's going on?

PS: It's nice to know these AVI files can be imported by all OS X applications. Now if only the D90 had a mic jack. What was Nikon thinking?

Although I can't help think that someone will soon take their D90 to a camera repair guy and have him open the case. Then cut off the mic and solder two fine wires. Then bring these fine wires through the mic grill to a jack glued to the case. Shielding these wires will be the hard part.
Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c
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Old December 25th, 2008, 06:08 PM   #2
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Join Date: Dec 2008
Location: Orlando, FL - USA
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FCP supports multiple formats in one timeline


I don't know about the other apps but Apple made FCP able to handle multiple formats in one time-line around the upgrade to Studio 2. I'd been able to do that in Sony Vegas and it helped FCP stand up in the real world.

On the computer video playback frame rates shifts all the time in response to processor load, drive speed, etc. Open the info window (apple-i) while QT plays a file and you'll see the frame rate move up and down - lots. Still the video plays as "normal" and you don't perceive the shift unless it gets way slow and stutters.

All that changes when you render. Now the codec will make all files conform to your settings. Mixed format time-lines will get weird, sometimes in a good way, mostly not.

At any rate (pun intended), I like to convert the AVI file from my D90 into RS422 .mov format before editing. There are lots of benefits and the only cost is larger files (about 4x increase) and a little time (much less than the real time investment of ingesting HDV footage).

As for the D90 mic input problem... shielding the wires is not the hard part.

As you noticed, the D90 records audio at 11kHz. FCP likes 48kHz. Up converting audio does not increase the quality, it can actually make it worse. I recommend using a digital recorder capable of capturing a 48kHz audio file (like the Zoom H2 or better).

Yes, it's an additional step in the workflow to sync up the audio but it's my experience that it's worth it. You don't need to bother with cover shots and wide shots as you'll probably be using the audio track from another take anyway.

Plus, I usually strip the audio from my FCP edits, finish the tracks in Logic Pro then bring the mix back in under the original edit. Having decent quality original audio makes all the difference.

It's kind of like trying to use post-processing the correct a poorly lit scene. It's better to capture it right in the first place.

Which is why many people will never shoot anything serious with a D90 - they don't want to deal with all the issues. But I like it as a video capture tool enough to deal with the its quirks.

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