Concatenating videos with the Quicktime Player requires unnecessary decoding/encoding, with takes time and computational resources.

Solution: Concatente Files von FFMPEG

https://trac.ffmpeg.org/wiki/Concatenate

Using ffmpeg

1. Create a list: mylist.txt

   file '/path/to/file1.mp4'
   file '/path/to/file2.mp4'
   file '/path/to/file3.mp4'

2. Run ffmpeg ffmpeg -f concat -i mylist.txt -c copy output.mp4

Troubleshooting

[concat @ 0x7fc407904080] Unsafe file name '2008-08-05 21_38_08.mov' mylist.txt: Operation not permitted

Filenames should not have spaces, escape them with \.

That's basically it.

No more [@"string1" stringByAppendingString:@"string2"];

or [NSString stringWithFormat:@"string1%@", @"string1"];

just @"string1" @"string2" @"stringN" -> code>@"string1string2stringN"</code

The Objective-C 2.0 Programming Language.pdf, p131