Mencoder Splitting problems - Heeeelp!!!!!!

[mh2011]

I am recording my screen using camstudio with the clock timestamp on.

I then want to split into several chunks based on the times I give.

I am using the command(s) as follows :

mencoder 20111026_0758_03.avi -o myoutfile.avi -ovc copy -ss 21 -endpos 10

This should (as far as I know) give me a clip 21 seconds in and 10 seconds long.

Since I have the clock showing on the clip I can easily see if it has worked or not.

It hasnt when it should be 21 seconds in it is more like 1minute 27 seconds on the file created.

mencoder 20111026_0758_03.avi -o myoutfile.avi -ovc copy -ss 0 -endpos 10

Gives me a file 10seconds from the beginning.

This is driving me potty! How do I rectify this? Any help very much appreciated!

[Baldrick]

It looks right

Suppose you want to split video_input.avi such that you skip "approximately" the first 3.2 seconds and will take the next 2 seconds of video (until "approximately" second 5.2)
mencoder -ss 3.2 -endpos 2 -oac copy -ovc copy video_input.avi -o video_output.avi

What happens if you use "-ss 21 -endpos 31" ?

[mh2011]

Thanks for the quick response

Original Full Length avi
Starts Clock time - 7:58:04 - 1:01:22 long


tests

-ss 21 -endpos 31
Starts Clock Time 7:59:31 - 31 seconds long

-ss 21 -endpos 10
Starts Clock Time 7:59:31 - 10 seconds long


I have also tried with the options like -ss hh:mm:ss -endpos hh:mm:ss

Clearly it is skipping to the wrong part of the file on both tests. The fps rate is 5. I have also tried those options.

Any ideas?

:confused:

[intracube]

The -ss parameter has never worked reliably when I've tried it - no matter what time format is used

[mh2011]

I tried to get the same result using ffmpeg

what does "Invalid and inefficient vfw-avi packed B frames detected" mean?

[intracube]

what does "Invalid and inefficient vfw-avi packed B frames detected" mean?

A search threw up this thread. Check out posts #70 & #71.

[mh2011]

Bingo!

intracube your a genius.


The files I produce with camstudio contain packed bitstreams, this confuses the hell out of mencoder and ffmpeg wont accept the avi if it has these.

As you rightly pointed out you can use MPEG4Modifier to unpack the bitstream and save the file - this only takes seconds.

You can then feed this into FFMPEG as follows :

ffmpeg -ss 60 -t 10 -i my-unpacked_bitstreamfile.avi myclip.avi -acodec copy -vcodec copy

This produces a clip of my-unpacked_bitstreamfile.avi starting 60 seconds in and of duration 9 seconds. (notice its 1 second less, not sure why but just add 1). Apart from that its fine.

thanks for the help!

[intracube]

Bingo!

intracube your a genius.

Chris K, nbarzgar and Google deserve the credit here.

But thanks anyway