[MPlayer-users] Seeking (-ss) not accurate

[John Brown]

Hello All,

I am trying to convert a number of .OGM anime episodes to DVD. I thought
that I could save about 3 minutes per episode by keeping only one copy
of the opening song and the closing credits, and instructing the player
to play them at the appropriate times.

My problem is that seeking does not seem to be accurate. For example, at
the end of the opening song, the mplayer status line displays 97 s.
However (please view in fixed-width font):

                 Start Time   Start Time
cmd line          (OGM)          (MPEG)
-ss 87             100*           87
-ss 93             109            98*
-ss 97             109           104

* = Acceptable times - black screen between song and start of episode.

I understand that mplayer can only seek to a keyframe, and I suppose the
interval in the OGM may be large, but I use -lavcopts keyint=18 to
encode to MPEG. The source OGM is 23.976 fps and the destination MPEG is
30000/1001 fps. I assume that this means that my MPEG has 1 keyframe
every 0.6006 seconds. Why is it that at certain points, -ss is so
inaccurate? Could it be that mencoder is confused because the commercials
were cut out of the .OGM?

Can anyone suggest free tools (as in free beer) that I can use to:

1) Split the movies?
2) Split the subtitles?