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FCP single frame crossfade?

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craig Jurkoic
FCP single frame crossfade?
on Nov 16, 2010 at 8:23:05 am

Does a single frame audio crossfade in Final Cut timeline make any difference?


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Eric Toline
Re: FCP single frame crossfade?
on Nov 16, 2010 at 1:31:33 pm

In what? As long as the track stays in sync then I would say no.

Eric


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Jean-Christophe Boulay
Re: FCP single frame crossfade?
on Nov 16, 2010 at 2:18:57 pm

That's a mighty short crossfade! It can make a difference with a click caused by an audio region being cut wrong, as one frame is still 1600 samples. If you don't have any clicks and are trying to smooth a transition, one frame is much too short. Clicks are best dealt with using fade-ins and fade-outs on the offending region, rather than a crossfade, anyways.

IHTH

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Jordan Wolf
Re: FCP single frame crossfade?
on Nov 16, 2010 at 3:14:12 pm

As long as the fade happens at a zero crossing, there shouldn't be any click problems.

Wolf
<><


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craig Jurkoic
Re: FCP single frame crossfade?
on Nov 16, 2010 at 8:45:33 pm

Thanks for the answers.
I'm not an audio expert. In summary I'll take your answer as: "No, a 1 frame crossfade is meaningless unless there's a click."

In FCP I'm working at 16 bit, 48khz.

Two follow-up questions:

1. What's "a zero crossing"?

2. If one frame is virtually meaningless, what is the smallest crossfade you would use in such a timeline? 2Fr? 3Fr? That is what's the smallest practical crossfade?

Thanks, gentlemen.


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Ty Ford
Re: FCP single frame crossfade?
on Nov 16, 2010 at 8:52:04 pm

Hello Craig and welcome to the Cow Audio Forum.

After the smart answers given by others here, I'll ask a dumb question.

Why do you want to do a 1 frame audio crossfade?

Assuming 30 fps that's 1/30 of a second. If you're doing 24 fps, it's obviously 1/24 sec.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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craig Jurkoic
Re: FCP single frame crossfade?
on Nov 16, 2010 at 10:52:07 pm

Thanks Ty. Good question.
I don't;
I don't want to do a 1 Fr crossfade.
I'll explain.
I'm currently working on an edited project deemed exemplary by a nationally recognized digital media education / training company. The project includes lots of 1 Fr audio crossfades. I do not understand their value.
Since I don't want to assume they're editors are mistaken ( This company has access to the most knowledgeable editors on the planet ) I figured I'd ask you guys.
Does that make sense?

-Craig


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Terry Mikkelsen
Re: FCP single frame crossfade?
on Nov 16, 2010 at 9:02:16 pm

1. A zero crossing is in reference to the waveform of your audio and how it starts and stops. The easiest way to envision it is to think about a sine wave. It starts at zero, gently rises up to 1, then goes down to -1 (crossing zero along the way), and finally goes back up to end at zero. In theory, you want each piece of audio that you edit to start and end at zero so when butted up to each other, they match. Otherwise, to abruptly jump from one value to another value within a few samples will cause the audio (and speakers) to violently try and achieve this unnatural edit, causing a click, clack, chunk, or other unwanted noise.

2. The smallest x-fade to use is to use your ears. The piece may not require a fade at all. On the other hand, 15 frames maybe way too short for another piece. Its mostly feeling and interpretation, with a little technical limitations here and there.

Tech-T Productions
http://www.technical-t.com


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craig Jurkoic
Re: FCP single frame crossfade?
on Nov 16, 2010 at 10:55:52 pm

Thanks, Terry, for your explanation of a zero crossing.


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Ty Ford
Re: FCP single frame crossfade?
on Nov 16, 2010 at 10:58:17 pm

Terry's entirely right, Craig, but the client is doubly always right.

A 1fr xfade may sound bad for content or zero crossover reasons.

If you can do 'em and it doesn't click from a zero crossover error and the edit sound sound like c**p, then I guess you do 'em and ask, "May I have another?"

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Peter Groom
Re: FCP single frame crossfade?
on Nov 17, 2010 at 9:28:13 am

Im not convinced its even possible 9let alone desirable).
FCP like all NLEs (avid etc) only allows manipulation +oe - 1 frame. You have to tell it if the fade starts at the transition, ends there or crosses it. Whatever way, telling it to do a 1 f tx means saying here we are on frame 4- by frame 5 have transitioned. Thats a CUT!
I think it will have a minimum of 2 to satisfy the criteria for a cross fade.
I remember my AMS Audiofile used to put a really small (a few ms) on every cut to stop clicks.

Peter

Peter


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Jean-Christophe Boulay
Re: FCP single frame crossfade?
on Nov 17, 2010 at 8:02:41 pm

FCP can't edit picture on a grid smaller than 1 frame, of course, but it does for audio. 1 frame of video at NTSC framerates is still over 1000 samples, so there is ample material to fade in. A quick test with a 1-frame fade on a sine wave in an FCP7 timeline does give a clear ramp when importing to ProTools, not a square cut. It does not behave as a 1 frame video fade-in would.

Craig, if you opened a "teacher" session with short fades like this on every region, it's surely as a safety against clicks. While FCP will fade the audio between frames, it won't let you cut it between frames. This means that audio edited solely in FCP is more likely to have clicks, as you can't cut at the zero-crossing point unless it's smack dab on a frame boundary. Batch fades of very short duration just ensure the conformed audio is click-free. Those fades can't possibly be heard and they safeguard against something that definitely can be heard. Almost all OMFs I get from FCP editors for mixing jobs have theses fades at the head and tail of all regions. I've never had to remove them that I can remember, either. It lessens the chances of us playing the "chase the click" game in audio post. It's good practice, IMO.

IHTH,

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Ty Ford
Re: FCP single frame crossfade?
on Nov 17, 2010 at 8:10:02 pm

JC,

Actually, someone showed me how to do a less than one frame move (not necessarily the same as an edit, but useful nonetheless. Bring up a clip in the browser and hold shift down while you tug on the head of the clip. It will move subframe.

That's a great idea to eliminate crossfade click. As you may know Pro Tools, even PTLE, has that sort of feature.

Thanks so much for sharing! You really make it a worthwhile place.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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