Alpha-Nuva 2012-12-22 13:31:01

Go to File > Publish settings > Flash > Audio Stream (because I'm assuming you're streaming), and then set the bitrate higher (at least to a number equivalent to the fps you're using).

If you've already done this, then you may be in the same boat I was earlier this year. I had an animation that would go further out of sync as the movie went on. To remedy this, I simply staggered the frames (i.e. the sound came in a 1/4 of a second late, so I moved the animation down about 6 frames). It'll require a lot of guesswork, but it's the only other option.

Good luck and PM me if this helped.

JonBro 2012-12-22 13:43:39

You could try Publish settings > Flash > Audio Stream, and then changing that option to ADPCM. I've found that usually works to sync the sound in an .swf without any problems. The sound quality resulting from doing this varies somewhat, so it might not sound perfect, depending.
As for exporting the file as a video file like .avi, you might have to try adjusting the sound and video speed to sync things up by using another program entirely, like Adobe Premiere, Sony Vegas, or Camtasia Studio.

JonBro 2012-12-22 15:19:32

Another thing some people do is add actions in certain frames of the movie like
stop(); play();
because usually when audio starts to go out of sync, stopping the Flash movie and playing it again seems to re-sync it. So if there are any convenient spots in your movie to do that, that might also be worth a try.

MSGhero 2012-12-22 16:16:52

The best fix I've heard for this problem is to have sound playing constantly, even if it's just silence. In a separate layer, just play the silence for the duration of your movie, or mix all audio into one big mp3.

Twisted4000 2012-12-22 17:15:47

Yeah, like some others are saying, setting all of your audio to stream is a start, and make sure the quality is up really high so you don't get the whistles and pops. Also like MSGhero said, you can try having a single sound playing the entire time, whether it's music or silence. Just have it set to stream and loop it the entire video and surprisingly it usually works. Works for me!

sweetcommando 2012-12-22 17:23:07

Publish settings > Flash > Audio Stream and event. set the rate from 16 to 24 and the quality to best.

MOC-Productions 2012-12-23 19:14:01

I run into this problem all the time. The fix I've learned is kind of unorthodox, but it works.

If your movie is divided into scenes, you'll have to do this scene by scene. If not, it will be easy.

Export your flash as an audio file (wav/mp3/whatever). Once your sound file is exported, bring it into your library. Then create a Movie Clip and open it up. Make the movie clip as many frames as your flash (or scene). Then drop your audio file into that movie clip. Make sure the frame extends as long as the sound clip does.

Now that you have your sound clip in movie clip form, add said movie clip to your first frame and extend it to the end of the movie (or scene). Then clear out all your sounds from the original timeline. Test the movie and see if the sound delay still occurs. If you did everything right, the sound should stay perfectly in sync.

I know it sounds like a mess, but just remember, the overall goal is to get all of your sounds converted to one movie clip and let the movie clip act as your soundtrack. Don't ask me why, but it works flawlessly. So if none of these other techniques are working for you, try this one.