[MEncoder-users] Flash rotation help

[Corey Hickey]

Sean Brady wrote:
> Hi. Okay, so I have a flv file that was created using mencoder.  The
> command was something like so:
> 
> mencoder -of lavf -oac mp3lame -ovc lavc -lavcopts
> vcodec=flv:acodec=mp3:abitrate=64:vbitrate=400 -srate 22050 -ofps 15 -vf

If you use -oac mp3lame, then -lavcopts acodec=mp3:abitrate=64 has no 
effect. Either use -lameopts to tune lame's parameters or use -oac lavc 
to use lavc audio encoding.

> scale=400:300 a4e7c2ab298ffdfad27d568cc675b4a9.wmv -o test.flv
> 
> I've also added -rotate to the -vf list...  like so:  
> 
> -vf scale=400:300, rotate=1
> 
> which works great.... now here's the dilemma.  I need to make this work
> off of the .flv file, so instead of running this on the .wmv file and
> encoding it to .flv, I need to run it on a .flv file, and encode it to a
> new .flv file... basically trying to rotate the .flv file 90 degrees.  
> 
> I'm sure it's simple, but I just can't get anything to work!

Next time please tell us what you tried. Anyway, there are a few things:

1. You're using a build of mencoder that is at least somewhat old. You 
should upgrade to recent CVS. Actually, the CVS server is down at the 
moment (hardware failure), but you can get a snapshot here:
http://www.mplayerhq.hu/~rtogni/snapshots/

2. Re-encoding multiple times is a bad idea. I'm not sure if that's what 
you want to do, but your description sort of indicates that you're 
trying to encode wmv-->flv-->flv(rotated). When you re-encode using a 
lossy codec, information is lost, and doing so more than once compounds 
the difference. If you're talking about rotating and re-encoding files 
that were already flv by the time you got them, then you don't have any 
choice, but it's always best to use as close to the original as you can 
get. If you want to have one normal flv and one rotated flv, then do two 
encodes: wmv-->flv and wmv-->flv(rotated).

3. All that aside, this should work well enough to get you started:
$ mencoder flv.flv -vf rotate -oac copy -ovc lavc -lavcopts vcodec=flv \
-o rotated.flv -of lavf -lavfopts \
format=flv:i_certify_that_my_video_stream_does_not_use_b_frames

-Corey