syncing external audio

Hi folks - my first post here. Thanks for the wonderful resources you offer. I'm mostly an audio guy and very new to video editing and FCP X so please give me some slack

I naively volunteered to edit 18 hours of video from a seminar. The camera's audio is horrible - loads of background traffic noise that is so bad I can't improve it to an acceptable standard in Logic. Thankfully I also recorded the speakers on my Zoom H4 though only in mono and in MP3 format as I didn't expect to have to use it. Duh.

So the first thing I tried was to use FCP X's auto sync: I imported the H4 MP3's into a Logic project set to 48KHz and trimmed the regions to roughly the same duration as the DV clips. Within a second or so. I then convert these regions to new audio files - 16bit @48KHz. Open up FCP X and select the DV clip and the H4 audio and choose "Synchronise clips".

The result is very poor sync. Initially I thought this must be because of the high level of background noise defeating the FCP X sync algorithm. However when I then try to do it manually - and I can do this pretty precisely because of the applause claps at the start of the clips - the audio still falls out of sync after about 5 minutes, becoming very noticeable after 10 minutes.

Clearly I'm doing something wrong -- but I'm confused as to what!

Am I missing a step in preparing the audio? Is the problem perhaps with working from MP3's as the original source? Is there something I need to do in setting up the Logic project prior to conversion?

Any advice very much appreciated - I've got 18 hours of this to do and I really need to figure out an efficient work flow to get it done.

Thanks in advance!

Humm. Sounds like a sampling rate issue, or perhaps a drop frame. I've seen this before with my H4N. Unfortunately it was so long ago I don't quite remember the fix.

Why don't you try to pull the audio in straight from the H4N without the trip to logic. See if that makes any difference.

Also, in 10.0.1, I can confirm that you should be able to sync a whole bunch of video clips to a base audio track from the H4N with the Synchronize Clips command. So you don't really need the logic step anyway. Make sure you wait for the sync to complete, check the background tasks in FCP X (command-9) to watch the progress.

Thanks for this info. Will definitely give it a try!

Wondering how far this would go? For example throughout the seminar there were a few occasions when I switched the camera off during coffee breaks but forgot to switch off the H4. Is it smart enough to sync the audio with non-continuous video?

Of course I'll experiment, but if you guys already know the answer?

cheers and thanks again.

Yes that is what I meant. It should work fine in 10.0.1. (this didn't work in 10.0.0)

Wow - okay if I can get that to work it will save me HUGE amounts of time.

DV audio standard is 48kHz, 16-bit, aiff and all audio brought into FCPX should be that. Yes, if sample rate is other than 48kHz you will get sync drift over time.

That's what I'd understood which is why I was bringing the MP3 audio into Logic at 48kHz. It's also why I was/am puzzled as to why I'm getting so much sync drift (thanks for the terminology)

Is your opinion that importing the MP3 files directly into FCP X is unlikely to work?

MP3 is not a professional format, being too compressed. Convert to AIFF. It's never been supported by FCP. Horrible audio codec only good for music delivery online. Record and edit AIFF at 48/16 only. If yore recording as MP3, it's like recording 1080 HD video as MPEG-1. You loose all that great quality in the codecs outrageous amount of compression.

Thank you, but as someone with a fairly respectable home studio I'm familiar with the "horribleness" of MP3. However for recording spoken word in a seminar setting when said seminar was abroad and the whole thing was done for love . . . well it's done the job and frankly saved the day given the audio on the tapes.

For sure in future I'll be splashing out on more SD cards and recording to AIFF, but for now it's what I've got to work with. All 18 hours of it!

So the question is whether or not you're disagreeing with tpayton's suggestion of trying to import the MP3 direct into FCP X for auto sync to the DV?

thank you

You couldn't pay me enough to use MP3 files in FCP. No, convert to AIFF (PCM) for sync, or any other use. It's the native format for all DV codecs, reduces CPU usage, faster for FCP to process.

Also, background noise can make it difficult for FCP x to do it's automatic sync process. I've found it doesn't even need to be horrible, either. Looking forward to that algorithm being improved in future releases.

If you have lots and lots to sync, PluralEyes is the way to go.

Btw. Plural Eyes is finalizing their fcp x support right now, so your best bet is the standalone demo of plural eyes. You can grab it on their site as a fully functional demo.

Thanks - Plural Eyes looks fantastic and just the job. I can't find any reference to a standalone version though? The download links seem to point to versions specific to various app hosts?

Am I being dense?

We are all hopelessly dense. You're in good company.

The stand alone product is called Dual Eyes. Here it is:

www.singularsoftware.com/dualeyes.html

You can grab the demo.

ahhh thanks so much! Looks like I'll be buying the FCP X version when its available but in the meantime a fully functional 30 day demo of Dual Eyes is very very handy!

cheers

Did it work? Is the audio in sync by using the files right off the H4n?

Haven't had chance to play with it yet - the day job pays the bills!

Will post back when I've had a bit of an experiment with the various options.

thanks

Finally had chance to have a play with Dual Eyes. With drift and "try harder" selected it did manage to create a sync file. However when I drop this into the timeline it's not even close to being in sync with the video. Should I be creating a sync file inside FCP or selecting the option to have it replace the audio on the .MOV for optimum results in your experience?

thanks!

Without really seeing your cilps and audio it is difficult to know what the problem is.

However at this point I would think that if FCP X and DualEyes both didn't product a good sync that you're going to have to do the sync manually. It's really not that hard at all. Since FCP X lets you nudge audio by the subframe you shouldn't have that much trouble.

I'm just curious, did you actually try the FCP X sync with the original MP3's?

Again, if the background noise is too much, nothing will sync it properly.

thanks both

I tried the mp3's with both FCPX and Dual Eyes - no good.

Now I've kinda got the hang of it seems quicker to manually sync at this stage. Though I might have another play with cleaning up the original - this will not produce a good enough audio, but it might save time if the audio files will then sync. Many thanks