In MPEG Streamclip, there's a difference between the various "Export" and "Convert" options. "Export" does encoding. "Convert" only converts between the various flavors of MPEG-1 and -2; basically between transport and program streams, and between audio formats. It also cuts and joins streams. The source must already be MPEG, otherwise the menu options are disabled. Of note, these functions do not require the MPEG-2 Playback Component (it's not really "looking at" the video).
MPEG-2 playback and encoding have license costs. The MPEG-2 Playback Component was already out there. Why would MPEG Streamclip reinvent the wheel and pay the fee, which would have to be passed on to users? (Perhaps as a result, Apple paid the license for MPEG-4, covering personal and non-commercial use, with no additional fee for the end-user.)
As the name suggests, the Playback Component does not encode. So as to the original problem.... First, you can rename any file so that it has an .mpg or .mpeg extension. That doesn't say much for a "scientific" journal. But if you want to create an MPEG-2 file using only what's on a vanilla Mac and free software, you can use iDVD, since DVDs are MPEG-2:
- Use iDVD to create a new project. You can save a little time by choosing a simple theme (without animation).
- Drag the movie you want to convert onto the menu, which should create a menu item. You can preview the DVD.
- Under the File menu, choose Save As Disk Image. This will convert the movie into MPEG-2, without actually burning a disc.
- Open the .img file that was created. It will mount as a new drive. Go into the VIDEO_TS folder. Your movie comprises the VTS_01_?.VOB files. Depending on the length of the movie, you might have more than one (they are limited to 1GB each). You don't care about the one named VTS_01_0.VOB, if it's there; that's the chapter menu. You want the ones starting with _1.
- If there is just the one VTS_01_1.VOB, then that's it. Rename that file to something with a .mpg extension.
- If there is more than one, now you can use MPEG Streamclip. In the Open Files dialog, be sure to sort by name. Then select all the files starting with _1 (again, not _0 if present). Then under the File menu, Convert to MPEG; that will join the files together.
- You actually might prefer Convert to MPEG with MP2 Audio. It will make the file smaller, and you can hear audio in QuickTime Player (with the MPEG-2 Playback Component). If it's just one file, you can Convert that too.
Note that if you don't have the MPEG-2 Playback Component, you can still do the work -- you just can't see what you're doing. (The DVD Player will only play MPEGs that are part of DVDs.) Unless you've got something else installed to play them. And for this, you don't actually need QuickTime Pro.
