[MPlayer-dev-eng] Darkening of picture on most mplayer outputs

[Haakon Riiser]

While experimenting with dumping and reencoding picture sequences, I
have noticed that there is a significant darkening of the picture on
most mplayer outputs.  Here's a simple demonstration:

  $ wget http://folk.uio.no/hakonrk/tmp/mplayer-darkening-bug/source.jpg
  $ mencoder -ovc copy mf://source.jpg -o 1.avi
  $ mplayer -vo jpeg:quality=100 1.avi

Now compare the dumped frame (00000001.jpg) to source.jpg:

http://folk.uio.no/hakonrk/tmp/mplayer-darkening-bug/00000001.jpg

As one can clearly see, the picture gets significantly darker on
every 'mplayer -vo xxx' operation (the picture gets just as dark when
I output to Xv or X11, or any other on-screen output).

I have found _one_ single exception to this:  If I output to
yuv4mpeg, the brightness remains the same.  That is, it will look
as bright as the original picture if you look at the generated
stream.yuv file with another program.  If you look at it with
mplayer, it will look just as dark as 00000001.jpg above.

I first thought there might be a post-processing filter that caused
this, but I have used an empty ~/.mplayer/config and
/usr/local/etc/mplayer/mplayer.conf so there should not be any
filters.  Here's my mplayer output from the -vo jpeg step, in
case it matters:

http://folk.uio.no/hakonrk/tmp/mplayer-darkening-bug/mplayer-output.txt

As you can see in this log, I'm using mplayer/mencoder dev-SVN-r26205-4.1.2

-- 
 Haakon