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AAC audio issues in AME

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Bill Latka
AAC audio issues in AME
on Jan 15, 2011 at 4:11:26 am

We are using Adobe Media Encoder CS5 to export .F4V files, but are having a heck of a time getting the audio right. When using all flavors of AAC (tried all bitrates, AAC+ versions 1 & 2) we are getting a crazy yet subtle stutter in some of the passages of audio and some of the voices. The most offending part are where we have the sound of wind in the clip that turns all stuttery. Sounds like compression artifacts if you will. We're also getting a subtle echo in some of the speech.

When we compress to FLV which of course uses MP3 audio, the MP3 audio is fine, but the video doesn't look as good (the nicer H.264 vs. the older On2 VP6 codec). We've tried exporting with Sorenson Squeeze 6.5 and the AAC audio sounds great. But since Squeeze doesn't support F4V this doesn't work for our needs. We need the F4V to embed Cue Points correctly for our Flash application.

We also tried using an exported 44.1 kHz movie from Final Cut instead of the native 48 kHz audio on our timeline but that didn't seem to help.

Any suggestions to fix this audio problem?
Any suggestions of other compressors that will output a F4V with cue points?


OUR DEETS:
Computer - Mac OS X 10.6.5
Software - Adobe Media Encoder CS5 v. 5.0
Source codec - ProRes 422, 1440x1080, 48 kHz, stereo, output from Final Cut Pro 7.0.3
Destination codec - F4V with AAC audio, 44.1 hHz, High audio Quality
Type of destination use - Flash streaming server.

Thanks everyone.



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Jeff Greenberg
Re: AAC audio issues in AME
on Jan 15, 2011 at 5:50:08 pm

No idea (to be honest) of what's causing the problem.

Two ideas to try and reduce it.
I'm guessing that the moments with the wind may have some audio peaking.

One - could you try a compressor on your audio to minimize the dynamic range?
Two - could you try dropping the overall level of your audio output.

Best,

Jeff G


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rob williams
Re: AAC audio issues in AME
on Oct 29, 2011 at 10:12:39 pm

Hey Bill - I am having exactly the same issue and was wondering if you had found a way around this audio problem?

Many thanks


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Jack Gladney
Re: AAC audio issues in AME
on Apr 14, 2012 at 11:52:32 pm

I've been struggling with exactly this same issue -- encoding f4v from AME cs5 (and 5.5) and getting a subtle echo or vibrato on the audio track. My source video is ProRes, and I've tried multiple audio codecs as source audio from mp3 to wav, 44.1 kHz and 48, with no audible difference in the final result. I've also found that when encoding AAC in AME using the h264 or flv presets, the sound comes out fine. Only when encoding f4v do I get this echo.

Has anybody figured out a way to correct this? Is this just the audio quality one should expect when encoding f4v in AME? Greatly appreciate any help, here -- MANY thanks.

Working on a 2011 Macbook Pro, Lion 10.7.3 (but have encountered this issue on multiple mac systems and operating systems, including Snow Leopard).

Best,
Jack


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