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Working With Direct Audio Copy Aac Audio, Saved video has AAC problem audio [VBR]
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-vdub-
Posted: Jun 21 2013, 07:46 PM


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Example: Video MP4-AVC1/AAC LC the problem arises save to AVI using Direct Copy for audio. The AVI saved will have the audio saved as..

fcchandler QuickTime plugin - AAC
raytheon FFMpeg Input Driver - PCM

Fcchandler QuickTime plugin saves the AAC audio though after load the saved video to virtualdub there is an error.
AVI: Variable bitrate [VBR] audio detected which is good nice to be warned of this. Problem next is we cannot work with this further with the audio as there is no AAC compressor for use with virtualdub atm

Example video could be any MP4-AVC1-AAC video though I chose this as shows the problem
direct: http://www.evropej.com/compression.mp4
non direct: http://evropej.com/compression/compression.html then download compression.mp4 video

@ phaeron Hope this is in the realm of been able to be fixed for virtualdub else a lot of work involved otherwise to overcome the current AAC limitation. Maybe you support MP4-AVC1/AAC loading direct with your plugin which would be preferred. Though as all video mainly now are x264 AVC1/AAC and sooner or later there be x265 AVCx/AAC


I read that AVIMux can overcome this problem for AAC LC. Which would mean the need to demux before or after processing with virtualdub. Then also not knowing if the sync will be maintained after doing so is one main reason to be able to have AAC LC compatibility with virtualdub.

Is this a problem with fcchandlers AAC-ACM where able to load source without error. Only after virtualdub saving it to AVI with direct audio will virtualdub complain about VBR. If this the problem maybe fcchandlers aac can be fixed to correct this (that is not to mask the problem but to fix it). I know really the answer is we need an AAC encoder to use with virtualdub that can set other option than VBR for example CBR or other so virtualdub doesn't complain.

Knowing avi cannot have VBR is one thing but how many player would be affected with AAC. Is this the same as it was with MP3 VBR ? though I doubt since would have a working VFW or ACM AAC LC encoder to overcome this to encode to something other than VBR. Or can the same fix as MP3 be applied to AAC LC. To many variables yet no solution for AAC LC which is good for h264-AVC1 video
 
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