joining two avi parts that overlap?

[nok32]

hi, this is my first attempt to edit video of an sort. i have a film that is cut into two ~500mb parts and i am trying to join them without re-encoding. unfortunately, there is a ~2sec overlap. i used avidemux to append the second part to the first, but then i realized that a couple seconds repeats. what is the easiest way to edit the overlap out? should i try to trim the second part? is there any way to do this exactly so the two parts will match up perfectly? thanks.

[guns1inger]

Only by trying it. I would append the two parts in AVIDemux, then isolate the area to trim, and see how smooth it is. If you aren't happy, try again until you are. This is the price you pay for downloading.

[nok32]

ok. thanks. i think i got it perfect. is avidemux the fastest for joining? it took around 10 minutes for this film (on a 1.2ghz pentium m). is that normal?

[guns1inger]

It should have done very minimal re-encoding - only at the cut and join GOPs - however given the age of your system I would be guessing you only have a single drive as well, so 10 minutes would be about right. The bulk of the time is simply data copying, and that is pretty much software independent.

[nok32]

ok. i am sure it is also slower on my system since my (single) drive is a 1.8" 4,200. (i love my fujitsu p7120)

one more thing-- the files size dropped 20-30mb, even before trimming. seems odd since i was just copying.

[guns1inger]

Combining files will reduce some overhead data because you won't need all the header info from the second file. Also, if you enabled Smart rendering and took the default Quant value of 4, some 300 or so frames will have been re-encoded at a potentially lower bitrate than they previously held. if you joined first, saved, then trimmed, you will have re-encoded this section twice in this manner. Better to join and trim in a single pass so you only re-encode once. Also, reduce the quant to 3, or better yet, 2 and you will keep the quality you started with (although you may add a few MB to the final size)

[nok32]

cool. that is exactly how i did it, actually. (trimmed the first part, appended the second part, saved with a q-factor of 2). i guess the overhead is just that large. good to know.