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View Full Version : TECHNICAL: Remux not re-encode xvid avi's




snowmoon
Oct 25, 2005, 11:38 AM
Following on the success of my last thread here is a new one for you all. First off, as always, this post is for the technical among us. If this does not work for you PLEASE don't post unless you are farmiliar with video encoding.

For this test I used the ffmpeg from ffmpegx. The goal was to convert an .avi into a iPod playable file with little to no re-encode step. THIS WILL ONLY WORK IF THE VIDEO IS ALREADY IPOD COMPLIANT... no Quarter Pixel ( qpel ) no Global Motion Compensation ( gmc ) Resoultion and Bitrate compliant. The good news is many of the mpeg-4 video content out there is. This could include xvid and divx content

THIS WILL NOT WORK WITH EVERYTHING... I can't help that... but this process is easy to do and quick before you bother to do a time consuming re-encode.

I downloaded a copy of "The daily Show" from a torrent as a test. 512x384 xvid with mp3.

ffmpeg -i input.avi -vcodec copy -vtag mp4v -bufsize 4096 -maxrate 2350 -acodec aac -ab 96 -f mov output.mov

note: audio is recompressed to aac on the fly since we need aac. If the audio is already aac -acodec should be "copy" as well and -ab is unnecessary

I knew this should be possible, but until today I coudn't get the right voo-doo to get the video codec to be picked up by QuickTime. This re-packaging of .avi files also opens up some interesting possibilities on getting proerlt encoded vide onto the ipod since there are many many more tools for .avi files than there are for .mov files ( sorry ). I'm going to try re-running some of my earlier 480x480 tests through this system to see if we can come up with something that's useful again.

I HAVE NOT FULLY TESTED THIS, BUT IT SHOULD WORK! YMMV IANAL!