Someone please help. I just want to join two mp4 files. NOT ONE OF THE 20 OR SO 'FILE JOINERS' ON OFFER WORKS. I don't want to make a movie, convert to pdf, ALL I WANT TO DO IS JOIN TWO FILES, SIMPLY. For a PC user, hjsplit does this, effortlessly.

Okay. Then I have to assume your files were split as binary pieces and need to be concatenated back together. In that case, you can do this in Terminal.

Example:

cat file1 file2 file3 > newfile

You can leave the files named the way they are now. You don't have to go back to the .001 and such names. Assuming there are only two files, it would be:

cat part1.mp4 part2.mp4 > movie.mp4

This is simplified and assumes the files you want to join are in the current folder Unix (Terminal) is set to. Do this:

1. Create a folder on your desktop. Keep it simple. Such as, name the folder z .
2. Put your binary pieces into the folder.
3. Launch Terminal from the /Applications/Utilities/ folder.
4. Type the following in Terminal and press Enter: cd ~/Desktop/z
5. Type cat part1.mp4 part2.mp4 > movie.mp4 , or whatever you want the output file name to be.

Test to see if the output file opens. It should.

Edit: I tried to cat two .mov files and it didn't work. You may need to first rename the files back to mp4.001 and mp4.002 .

There's nothing difficult about it. Open one file in the supplied QuickTime Player. In the menu, choose Edit > Add Clip to End… . Choose the file you want to add. The next video will be added directly behind the first. Click the Done button. Save it.

It's not absurd. It's failing to open the file because it's treating the .001 as an unknown file extension. This isn't DOS where you can join split pieces right on the command line with:

copy/b mp4.001+mp4.002 movie.mp4

Give the files the correct names and it will work. Rename the first one as part1.mp4, and the next as part2.mp4. Now open them in QuickTime to put the two together.

QuickTime will open a proper .mp4 video. It won't if it is actually an .m4v video, or some other video format masquerading as an .mp4 file type. The annoyance with QuickTime is that it will export to a .mov, and not retain the .mp4 on the combined movie.

You can then take that .mov into Handbrake 1.2.0 and choose an appropriate Preset, and then convert to .mp4.

That 001, 002 etc suffix looks very like parts of a file that's been split into pieces and would require reassembly by the app that did the splitting. Without a: that app. and b: all the parts (if there are more), you're going nowhere I'm afraid.

Post a link to these files and others here can give it a try to see what's going on.

As Terence noted, if there's more than two parts, it won't work no matter what you do. All files have a header that tell the OS/app how many bytes to expect. If there's (for example) three binary parts, and you only assemble two, the resulting file will likely fail to open as the expected data size is wrong.

Good catch, VikingOSX. I had forgotten the latest version of QuickTime only creates .mov files. I was thinking of the Pro version of QT7, which outputs all kinds of file formats.

An mp4 is just a container. If QuickTime can play both clips you can merge them.

Select one of the files, press "command + I". In the window that opens, what does it say under "More Info:"?

You can also open the first video, and then just drag/drop the second onto the opened video and it will append to the end in the timeline. Then Save…

Does VLC Player open them?

If not...

https://videoconverter.wondershare.com/vlc/mp4-not-playing-on-vlc-player.html

Yup, there's a few ways to do it.