Syncing audio & video: amateur video editor seeks advice

Discussion in 'Digital Video' started by hwrdrrk, Sep 13, 2013.

  1. hwrdrrk macrumors member

    Aug 14, 2010
    Hello -- I'm an avid mac user and professional musician, but I've not kept up too well with video editing over the years.

    The basic question: What is a simple and easy way for me to sync an audio file (The higher quality vocal track as AIFF or MP3) with a video file (AVCHD to MOV with the lower quality sound)

    I've got a copy of FCP7 running on my iMac, but it all seems so clunky: import video file, import audio file, move audio track millimeter by millimeter until audio syncs exactly with me moving my mouth. Render for ages. Then export.

    I'm wondering if I should be getting FCP X for more AVCHD and advanced fluidity ... or use some simple technique in iMovie or download a recommended app from the app store? Or switch over to Adobe software?

    Or does quicktime have some extension where i can drag an audio file onto it and it will sync up with the video track at the correct time.

    Any help is appreciated!
  2. handsome pete macrumors 68000

    Aug 15, 2008
    I believe the new NLE versions have syncing capabilities included, but since you have FCP7 I would check out Pluraleyes. It's made to do exactly this. And I believe they have a free trial.

    Why are your renders taking so long? Are you talking about the final export? That's going to take a long time with pretty much any software if you're compressing to a different codec.
  3. simsaladimbamba

    Nov 28, 2010
    The rendering takes that long, as FCP 7 is not made for non-editing codecs like H.264 and the like. It prefers Apple Intermediate Codec or ProRes, and if you footage would be transcoded to a .mov file using either of these codecs, then there would be no need to render.
    The same goes for the AAC audio in the H.264 .mov file. It is not an editable audio codec, or editing friendly, thus if you use MPEG Streamclip or FCP's own import feature for file based video data, you can convert that blood .mov to a .mov either using ProRes or Apple Intermediate Codec and Uncompressed Linear PCM audio.

    Video Compression
    Why It Matters & How To Make The Most Of It

    And synching is relatively simple, I have synched up to eight cameras with external audio in Avid, you could just compare waveforms for example and use the trimming function of moving the audio clip one frame left or right and so on, if FCP 7 allows that, I do not remember anymore.

  4. jamesollor macrumors newbie

    Oct 14, 2013
    United States
    Go for adobe software because it is in demand plus as it is very popular your quries regaring any problem will be solved on answer sites.
  5. Chad3eleven macrumors regular

    Dec 11, 2012
    First off, you may not have your sequence settings set up properly.

    They should match your video content.. that could be why you are rendering so long..

    Second, I've used pluralyes and its great, not sure how it handles AVCHD.

    Third.. yes stringing out audio can be tedious, but if you prep it right it wont.

    what are you shooting? is it possible to slate it?

    The simple technique of getting your cameras and audio recording device rolling, then using a slate/clap board, or just your hands to make a visual and audio slate can shave off hours of work. Be sure to say "Take 2", make the symbol with your fingers (or write it on a board) then clap..

    thats the basics for production..
  6. ChrisA macrumors G4

    Jan 5, 2006
    Redondo Beach, California
    FCP X works well. It will automatically sync your audio recordings if you record the video using the camera's built-in mic. Yes the built-inmic sounds bad but you don't use the sound, you sync a separate recording and FCPX looks at the waveforms and makes them match, then you remove the built-in mic's sound or set the volume to "mute"

    The other method that has been used for years is a clap board. Lacking that a hand clap works. Then you move the spike in the audio to the frame where the clap is first closed. But the better technique is to use the built-in mic so the sync can be done automatically. The sync is way better and is accurate to one audio sample.

    FCP X is easy to use but offers MANY variation in work flow. For example when you import you can transcode or not.
  7. SpaceTimeRoger macrumors newbie

    Oct 21, 2013
    The only way to really do it right, is to use a slate. You need the visual indicator of the slate closing, as well as the sound spike on your external audio recorder in order to accomplish a perfect match.

    PluralEyes, etc., do a fair job, and can be useful for doing multicam work, or if you have a lot of clips, however, it isn't a perfect sync. PluralEyes will sync your external audio recording with the original, on-camera audio recording.

    The problem with the above, is that the on-camera audio recordings (especially on DSLRs, but it affects virtually all video cameras to varying degrees) are almost always out of sync with the camera's picture. You can test this yourself with a slate and just the on-camera mic. You'll typically find that the on-camera sound spike is 2-3 frames out of sync with the picture. Doesn't sound like much...but w/24p video it's about 10% off. So if you use Plural Eyes, all you are doing is matching the new audio to the already out of sync on-camera audio.

    So the only way to get it perfect, and the easiest way (once you get used to it), is to use a slate and an external recorder, and then match the sound spike from the external audio to the picture on the first frame on which the slate closes. You can use a hand-clap as well, but it's much more difficult to get a good visual indicator from that.

    You'll be able to sync audio to video very, very quickly once you get good at this. Just pull up your video clip, go to the first frame where the slate is closed, and set a marker. Pull up the audio, find the first frame in which you can hear the spike, set a marker, and line 'em up. No more guessing.

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