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I just did the sound design on a Valentines Day promo for Volcom and the one they uploaded to YouTube seems to be out of sync and phasey, where as my original is not at all. Can anyone explain to me what happened and how I can prevent this in the future? Below are links to both cuts.

Original: http://vimeo.com/36594353

YouTube version: http://youtu.be/1BxpGDqXzW4

Thanks!

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  • To me it sounds like the audio is there twice, with a tiny delay between the two. Could it be that somehow the video with audio already in it was imported in some program, and then the separate audio track was added again?
    – EMV
    Commented Feb 15, 2012 at 18:26

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georgi answer is great, but it might simply be a YouTube issue. This happens often. Just recently, a friend of mine uploaded a video to it and L and R were switched!

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  • Weird. Was the audio stream embedded within the uploaded as two separate mono streams or a single stereo interleave? Quicktime is capable of both. For TV work we sometimes get QT files that have two separate mono streams, one for DX and the other for FX/MX - but they're not panned so-to-speak.
    – Stavrosound
    Commented Feb 29, 2012 at 1:14
  • I think he used Camtasia presets, don't know exactly if two mono, but I'd risk with the stereo interleave. What I do to go around this is to use the presets from Adobe Media Encoder. The file turns really small preserving the quality of both image and audio (AC3) I also have the idea that Vimeo is much more professional not only because of its contests but the conversions it does internally with videos in general don't carry much loss, and that maybe explains what happened. Good luck!
    – Melissa Pons
    Commented Feb 29, 2012 at 14:06
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codecs.

To keep video and audio in sync you're relying on sample-perfect decoding and this can go wrong very often (think audio interface does not support 44.1kHz sample rate for instance, true story from Creative Labs). To avoid this, older codecs used to feature audio/video interleaving, so the relevant audio went hand in hand with the relevant video. You can notice this on older divx videos that tend to skip a frame every so often. Newer containers such as Quicktime/h264 have a timebase parameter so it's no problem to sync things.

So when transcoding your video, the following could go wrong:

  • It was wrongly encoded at the source. Say your encoder component was a bit off. Adobe tend to cause this often.
  • It was wrongly decoded for the purposes of transcoding. Say your codec component was exotic so the video host's one got things wrong (happens to a lot of opensource).
  • The transcoded video was then wrongly decoded by your computer. This does not necessarily mean it would happen (or not) on other computers. It's not entirely predictable.
  • Everything is fine at source, transcoding, and decoding, but the hardware is locked at a different sample rate. No way to predict what's going to happen if your player/component/OS does not cater for this. OSX does, to my awareness.

Things to try:

  • Try the other "quality" settings (480p, 720p).
  • Restart your browser.
  • Reupload in a super-common format: mpeg4 h264 48khz stereo and cross your fingers.

(They did sound different to me so it might be the third option you're heading towards. Also consider the "internet weather" sometimes causing SNAFUs even on the biggest sites.)

Hope this helps.

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  • @georgi.m The session was 48/24 and I bounced it down to a wav file. Then I sent it to the Director. They wanted to lay the track in FCP and render it out to a QT file, just in case they wanted to cut off a few seconds of a black in the beginning and end. Is there a possibility the director could had done something to the audio to cause it to sound the way it does? And if so, is there a way to prevent this?
    – Mitchell Scott
    Commented Feb 14, 2012 at 23:41
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    totally, and i've had it happen more than a few times. Outrageous idea but you can take their video file, add your sound track using Quicktime Pro and return the file back to them :) Alternatively, take the video, resync the audio from start to end and use QT Pro to export a video yourself.
    – georgi
    Commented Feb 16, 2012 at 10:28

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