Playing with Sound in Audacity

B

BlueLaw

Member
Hi,

I'm using FCP but I’d quite like to fiddle some of the the sound in Audacity
- yeah I've said it, fiddle.

When I export my movie for DVD its in the form of .m2v for the video and .aiff for the audio.

Can anyone think of any issues or obvious problems with me just importing the audio .aiff file into audacity and playing with it before writing it with the video onto DVD?

Thanks in advance guys!
D.
:huh:
 
Synch is a big issue. Never trust a zero-offset audio file to stay in synch. Make sure that your FCP edit has a 2-beep and a tail-pop before you migrate the audio to an audio editing platform. When you're done sweetenning the sound, you can then export the new mix as a stereo .aiff, bring it back into FCP, synch it up using the 2-beep and tail-pop, trim the beeps out of the timeline, and export the "marriage print" to DVD.

It is customary to use an interchange format such as OMF to bring the audio component of an FCP edit directly into an audio editing environment, region edits and all. Doing so allows you to further refine the audio edit, and provides region handles for performing cross-fades.
 
A "2-beep" or "2-pop" is a single-frame beep that corresponds with a single-frame visual indication (traditionally the "2" in a countdown leader, although any clearly visible image can be used). This is generally placed two seconds before the start of a program, and serves a number of purposes: it identifies the exact frame at which the program will start (because it will be followed by 2 seconds of black), and it provides a common point of reference for synchronizing picture and audio.

A "tail-pop" or "tail-pop" is simmilar simmilar to a 2-beep, except it is placed exactly two seconds after the last frame of program. Like the 2-beep, the tail-pop identifies the last frame of program, as well as providing a second synch reference at the end of the program. It is usually helpful to use a different image than the 2-beep, often upside down, and often with a hole punced in the centre.

While it may seem as though all these beeps aren't needed in today's digital workflow, such is not always the case. Video tapes should always have some kind of pre-roll on them, and a title card (listing program name and edit version) followed by a countdown leader is a good way to keep work tapes and master tapes organized. Of course, all of this technical information is removed from the distribution tape, but most broadcasters will insist some variation on this protocol. The presence of this countdown leader on work tapes will provide "pre-rool" for sound editors and mixers, which is especially important if any of them are working from a tape-based playback system. Its worth noting that the program should start on the hour (eg. the first frame of program should be 01:00:00;00), with the 2-beep ocurring at 00:59:58;00, and the countdown leader starting at 00:59:50;00. For multiple-reel projects, it is helpful to use the first-frame timecode as a handy way of numberring the reel (Reel 2 program starts at 02:00:00:00, reel 3 at 03:00:00:00, and so forth).

The main reason for the tail-pop is that it will quickly tell you whether or not you're audio and picture are drifting out of synch. Line up the 2-beep, and take a look at the tail pop. If the tail pop is out of synch, you have yourself a problem (but at least you're aware of it). Between the 2-beep, tail-pop, and timecode burn-in, you should be able to quickly and effectively identify any synch issues.

There is always the potential for synch drift when you're going from one platform to another (eg. FCP to Protools), but you should be able to keep it down to around 1/4 of a frame over the course of a half-hour program.
 
Thanks for the details! I'm not an audio expert but I have seen a few sync issues crop up in the past.
 
Big fan of two pops, but they are not always the answer in the digital non tape/ film world. For one thing FCP is no good at syncing up files by two pops. It can only move clips in full frame increments. If your off with file back and forths you will be off by a fraction of a frame (unless something went terribly wrong) and FCP will be usless at fixing that. The only reliable way I have found to sync a mix back to FCP or Avid is by bouncing your audio to match the start of your video and snapping them together in FCP. I love two pops for film but they are not so useful if done by folks who haven't been trained by the whip ;~)
I get projects with pops that are not where they are supposed to be, are not accompanied by a visual pop, aren't consistent reel to reel/ version to version etc. They are an added problem with FCP since the way they want you to do them will cause a slew of problems. FCP has a "generator" that creates the pops and count down leaders etc. Those "generators" are not in the time line and that makes syncing up the sound after a mix very difficult. So as a rule for new filmmakers and especially those on FCP I tell them not to use pops. It goes against the grain and personal preference but it has made the flow much more reliable and I spend a lot less time explaining why they have to do a new output and exactly how they need to do it.

To answer your original question. In theory you should be able to do what your talking about with out issues, but that is theory. If you just want to "mess around" with the sound then I would probably say do a send to Sound Track pro, You already have it and you will be working to picture so you should be able to avoid sync problems. If you really want to work with Audacity you need to bring it back into FCP and check sync before you make a DVD.

As SMuir explained above 2pop or head pop (in american film lingo) is exactly 2 seconds before FFOA (first Frame Of Action) and the Tail pop is exactly 2 seconds after LFOA (Last Frame Of Action). Both are acompanied by a visual pop (traditionaly a big white dot (a whole punched in the film) but a frame of white is fine and in a count down leader Right when the 2 shows up). A film or reel always starts on the hour (timecode wise) and conventionaly the hour reflects the reel number. So reel 1 has it's FFOA at 01:00:00:00. That puts the head pop at 00:59:58:00.
 
Noiz brings up a number of excellent points. I've also had problems with the "no sub-frame editing" issue in FCP, although I partially disagree about the use of zero-offset sessions (ie. the picture starts at precicely the first frame of action, with the sound doing likewise). The compromise that I often use is to request that the picture editor use the 2-beep as the first frame in the zero-offset file (while the first frame of action stays at 01:00:00;00), providing two seconds of preroll along with a two-beep and the added security of no-fuss zero-offset files. Many of the broadcaster's I've worked with require a two-beep on the broadcast tapes, so I usually advise editors to take that into account early on in the editorial proccess.

As mentioned, the "generate" tools in FCP are well-nigh useless, and I generally request that the leader and tail-pop be cut into the timeline itself.
 
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