Friday, March 18, 2011

ffmpeg Converting VOB or MP4 to FLV format

SkyHi @ Friday, March 18, 2011
Using "mencoder" to create "flv" from "VOB" DVD video format files

Many websites nowadays are using swf and flv file formats to play videos hosted on their site or sites, it's advantage is clear in that the file itself is often in comparison to regular video format files, smaller and easier to upload so the site is able to hold and run more video content with much less bandwidth than would normally be required.

#> mencoder inputfile.VOB -of lavf -ovc lavc -lavcopts vcodec=flv:vbitrate=150 -ofps 25 -oac mp3lame -lameopts abr:br=32 -srate 22050 -vf scale=720 -o outputfile.flv

In our first test video conversion format a file named VTS_01_2.VOB was successfully converted from a 776.9Mb file to a 17mb outputfile.flv although the video and audio was brilliant the file stopped short of it's actual completion target in other words outputfile.flv was considerably shorter than it should have been, we have concluded from this that the VOB file is corrupt and the conversion terminates at that point. Having obtained another dvd with which to copy from we tried again, you should not this recording was original obtained from a small video recorder and transfered to DVD which we then migrated to a flash video (flv). Below is how we archived it, please note the above mencoder script is different to the one below which did eventually work.

#> mplayer dvd://1 -dumpstream -dumpfile myvideo.vob
#> mencoder myvideo.vob -of lavf -ovc lavc -lavcopts vcodec=flv:vbitrate=150 -ofps 25 -oac mp3lame -lameopts abr:br=32 -srate 8000 -vf scale=720 -o outputfile.flv

It is important to note the above "mplayer" command it does not play the file not visibly at least but dumps or rips 1 or more VTS_01_n.VOB files into a single "vob" extension file that can then be converted into a video file format you require. The input file has been altered to reflect the file output from mplayer and "-srate" has been altered to "8000". If you think a graphical user interface is the way to go you may be right it would take a lot of the guess work and fun out of using command line, but for now command line seems much better than "gui". Ahh problems with the above it turns out with an "-srate of 8000" you might get some rapid clicking when transfered to a website or you tube, through some investigation and some trial and error we came up with the following which you might think is much better.

#> mplayer dvd://1 -dumpstream -dumpfile myvideo.vob
#> mencoder myvideo.vob -of lavf -ovc lavc -lavcopts vcodec=flv:vbitrate=150 -ofps 25 -oac mp3lame -lameopts abr:br=32 -srate 44100 -vf scale=720 -o outputfile.flv

The "flv" format files can only support 8000, 22050 and 44100 I believe for the available -srate.

Converting MP4 to FLV
ffmpeg -i myvideo.mp4 -ar 44100 myvideo.flv

Converting FLV TO SWF

ffmpeg -i input.flv -acodec copy -vcodec copy output.swf