Old 11-17-2020, 10:30 AM   #1
Fabian
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Default AAC introduces audible artifacts...

When I render my video with AAC, 128 kbps or 192 kbps doesn't matter, two issues occur:
1. The first 13 or so ms of the audio is not as it should be, and
2. There are clearly audible artifacts in the AAC render, not there in the original.

For the first issue, see here (click for larger pic):


For the second issue, you can listen to the first 2 seconds here:
Original: https://chalmersuniversity.box.com/s...5csbr3xmsx.wav
AAC render: https://chalmersuniversity.box.com/s...0wcjx5evnc.wav

Does anyone know a work around for these issues?

I tried to fix this by rendering mov/mp4 with mp3 as audio format instead, but... https://forum.cockos.com/showthread.php?p=2365990
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Old 11-17-2020, 10:37 AM   #2
Fergler
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The first issue may be video frame start, before rendering make sure your video files are aligned to the frame grid (right click the timeline ruler to enable this grid).
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Old 11-17-2020, 12:41 PM   #3
Fabian
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Quote:
Originally Posted by Fergler View Post
The first issue may be video frame start, before rendering make sure your video files are aligned to the frame grid (right click the timeline ruler to enable this grid).
Aha! Thanks.

True, the project did not start on the frame grid. And though it was 12-13 ms off from the closest frame, inserting empty space and moving the items to start on the grid did not resolve anything. The new AAC render is practically identical to the previous AAC render, artifacts and all.

EDIT: I just now rendered the audio to mp3, and used ffmpeg to replace the AAC audio on the video with the mp3. There are no (audible) artifacts in the mp3 file, but ffmpeg cut off the first 79 ms of the audio...
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Last edited by Fabian; 11-17-2020 at 12:50 PM.
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Old 11-20-2020, 12:12 PM   #4
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Playing around with this, from the command line I got ffmpeg to convert the wav to AAC using its native AAC encoder, and the artifacts and missing beginning of the audio turns up also there. So this seems to be a problem with ffmpeg's native AAC encoder.

And I'm using ffmpeg/libav DLL decoder v58.91.100, from ffmpeg-4.3.1-win64-shared.zip Zeranoe build.
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