[MEncoder-users] -ss seek position?

[belcampo]

jthompson wrote:
> Hi all!  I'm haveing a problem getting mencoder to recognise the -ss parameter. I'm using XP sp2 and the string I'm using is:
> 
> mencoder -ss 00:00:00 -endpos 00:00:05 -nosound -ovc copy SOURCE_FILE.mpg -of mpeg -o OUT_FILE.mpg
> 
> The behavior is quite odd. With start / stop :00/:05 mencoder returns 5.005 secs and 150 frames writtenm, :01/:05 returns the same 5.005 secs and 150 frames, :02/:05 returns 4.505 secs and 135 frames, :03/:05 returns 3.505 secs and 105 frames, :04/:05 returns 3.003 secs and 90 frames and :05/:05 returns 2.002 secs and 60 frames. My .mpg test clip is only 6 seconds but I have tried longer clips.
> 
> I've also tried it with a different mpeg, a mpeg encoded avi and a dv encoded .mov . They all exhibit really strange behavior though a couple times things did seem to go right ( the number of frames were correct - i just watched the console output) but I could not duplicate it. I've tried this out on 4 different computers and am having no luck. I appreciate any help that can be offered.
Conclusion mencoder sucks on -ss and -endpos. So does mplayer
Try mplayer -ss , from the command line, for you it is in DOS window, 
and watch the time codes if you change the values of -ss.
use ffmpeg, at least my self compiled version is reliable. Further if 
you are in PAL land, your source will have 25fps and if its DVB then 
every 12th, after 0.48 sec. you get an I-Frame.

You always have to start WITH and end BEFORE an I-Frame

The endpos function works like start at 00:00:00 till and INCLUDING 
00:00:05 the start of the 5th second, till the next I-Frame.

If you want simple math, make your start and stop places at multiples of 
6 seconds, or 1.2 seconds, or 10 * 6 sec. so at min. points.

ffmpeg also has -ss 00:00:00 -vframes 25 ... ..
and you'll get exactly 1 sec.
> 
> Best!
> dh
> 
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