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Audio out of sync after render

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Mike sternAudio out of sync after render
by on Jan 13, 2010 at 8:51:31 pm

Hey,
I ran into a weird problem.
I've made a video using after effects and combined it with sound (i know after effects isn't good for audio, but it was just a little project). When I RAM preview it, the audio and the video are synced just fine, although after i render the video, the final result is not synced.
The fps is the same in the ram preview and the render, so i can't figure out why does it happen.
Any ideas?


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Dave LaRondeRe: Audio out of sync after render
by on Jan 13, 2010 at 9:00:28 pm

[Mike stern] "Any ideas?"

Here's Mine:

Dave's Stock Answer #1:

If the footage you imported into AE is any kind of the following -- footage in an HDV acquisition codec, MPEG1, MPEG2, mp4, m2t, H.261 or H.264 -- you need to convert it to a different codec.

These kinds of footage use temporal, or interframe compression. They have keyframes at regular intervals, containing complete frame information. However, the frames in between do NOT have complete information. Interframe codecs toss out duplicated information.

In order to maintain peak rendering efficiency, AE needs complete information for each and every frame. But because these kinds of footage contain only partial information, AE freaks out, resulting in a wide variety of problems.


Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Mike sternRe: Audio out of sync after render
by on Jan 13, 2010 at 9:25:11 pm

Actually i didnt import anything, its only animation i made inside after effects mixed with sound which I imported..
So i guess thats not the problem


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Dave LaRondeRe: Audio out of sync after render
by on Jan 13, 2010 at 10:31:47 pm

Well, I don't know... are you using compressed audio like mp3 or ac3? AE doesn't like compressed audio either.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Mike sternRe: Audio out of sync after render
by on Jan 14, 2010 at 2:36:45 pm

nope. im using wav files..


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Dave LaRondeRe: Audio out of sync after render
by on Jan 14, 2010 at 4:37:06 pm

These are the final two things that I can think of:
  • Double check the audio sampling rate: you may have a discrepancy. The most common is 44.1/48 kHz. Resolve it.
  • There may be nothing wrong at all! Since we know squat about how you're playing back the file, or how you rendered the file, you could be in this situation: you may have rendered a high-quality file from AE (good), but your computer hard drive can't keep up with the high bitrate of a high-quality file. To reassure yourself that it's okay, take that AE-rendered file into an application (quicktime pro, Apple's Compressor, Adobe Media encoder) and make an mp4/h.264 version. Those are highly-compressed, final-delivery-only codecs, intended for playback.

In a pinch you could reimport the rendered file to AE and do the conversion, but it won't look great. And if neither of those two things work, there's something you're not telling us about your project.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Steven OrshonskyRe: Audio out of sync after render
by on Oct 21, 2011 at 6:50:02 pm

Okay, frequent visitor first time caller. We recorded a video clip on our new Panasonic HD camcorder and having the same problem. Recorded to a chip and extracted with Panasonic's viewer program. The file is 21 minutes long and 3.5GB in the m2t format. Seems like quite a large file size for the time. (Shot on green screen at 29.976 frames/sec.) Video skips and lags only when audio is previewed or rendered with the video. Renders okay without the audio.
After Effects CS4, Window Vista
2 questions: First, how do i convert to to a different codec. I tried running to an AVI through Correl Video Studio Pro 3x but same problem.
Second, what codecs work with After Effects?
Also, should it really take 11 hours to render?
Thanks!
Steve


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Lane ForceRe: Audio out of sync after render
by on Nov 11, 2011 at 3:05:09 pm

I have the same problem rendering h264 out of AE--my audio is always just a step behind when I render out the mp4 in h264 compression. Fine when I render uncompressed, but for some reason the audio lags a few frames when rendering out of AE to this format. What's up with that?


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