Andy Hedges’ Tech Blog

I have been working on having flash based videos on The Humor Archives as Flash seems to be the most widely supported video format on the web, mpeg, real, quicktime and windows video can not compete for the it-just-works factor.

However not all the video clips (read none) that I get given or find for The Humor Archives are in Flash video format (flv). Therefore I needed to find a way to transcode every format under the sun into flv. The formats I currently have are Quicktime (mov), Windows Media (wmv, asf, avi), mpeg (mpg) and Real (rm) in a veritable cornucopia of codex including but not limited to: wmv7, wmv8, wmv9, divx, xvid ,H.264.

I needed to get these all into the FLV format using the Sorenson codec so that a flash player could play them. Now I thought that ffmpeg would do the job but it turns out that it doesn’t support a number of common closed codecs like the horrible Microsoft ones and so I looked to mencoder (from the guys who make mplayer). Mencoder uses binary codecs from vendors such as Microsoft as well as a large collection of open codex such as xvid to decode the Video, it then uses the Sorenson3 codec in ffmpeg to encode the final flv file.

However things are rarely that simple, there are numerous command line options for mencoder. I tried many variations, including the ones in the mencoder documentation. However the results were a little poor - blocky, pixelated. I was beginning to lose hope - I even started to look at commercial software *gasp* spend money! However one of the variations paid off and gives almost perfect reproduction on all format to flv and here it is:


mencoder myfileinshitformat.wmv -o myfileinflvformat.flv \
-of lavf -oac mp3lame \
-lavcopts vcodec=flv:vbitrate=200:cbp:mv0:mbd=2:trell:v4mv:predia=2:dia=2:last_pred=3 \
-vf scale=320:240,harddup \
-lameopts br=64 -ovc lavc -ofps 25 -srate 22050 \
-lavfopts i_certify_that_my_video_stream_does_not_use_b_frames \


Obvious really…

Did I mention that mencoder is completely free?

Technorati Tags: mencoder, mplayer, flash, flv, video

This entry was posted on Tuesday, September 5th, 2006 at 7:53 pm and is filed under Open Source. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.