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Jim Shupert, Jr.

I have seen some conflicting comments about the use of   -async.

basically to keep audio and video in sync is the following *always true

1. the -async param always should come before  the  -i  InputFile  parame
as in
ffmpeg -async 15 -i inPut.mov -vcodec mpeg4 -r 15 -deinterlace -y  -s
480x360 -b 400k -acodec libfaac -ab 48k -ar 44100 Output.mp4

meaning if -async is called later it is 'wrong' or ignored?
ffmpeg  -i inPut.mov -vcodec mpeg4 -r 15 -deinterlace -y  -s 480x360 -b
400k -async 15 -acodec libfaac -ab 48k -ar 44100 Output.mp4  < would be

2. it is best to have the -async Num  grow and be == to the fps Num
as in
ffmpeg -async 15 -i inPut.mov -vcodec mpeg4 -r 15
ffmpeg -async 24 -i inPut.mov -vcodec mpeg4 -r 24
ffmpeg -async 30 -i inPut.mov -vcodec mpeg4 -r 30


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