MJPEG (Motion JPEG) compression has been around for quite a while, but there has been a resurgence recently, when Nikon and a few others began shooting motion with their DSLR and other still cameras.
Some systems have MJPEG CODEC’s installed already, and some NLE programs also include them with installation. Many camera mfgrs. will include one (often tweaked to their specs.) on their utilities disc. One might be installing it along with the driver for the camera, or perhaps with the installation of the utilities on that disc. The latter is becoming more popular with camera mfgrs., but a separate installation for the particular CODEC would be a better solution. That seems to be falling out of favor, amongst camera mfgrs. though.
If one is getting the “Unsupported Format/CODEC” message, it could well be that their system does not have an MJPEG CODEC installed, or the version that they do have is not matched to the one used by their camera, or it could be that their NLE (Non Linear Editor) program, just cannot use that particular version.
There are two very popular commercial MJPEG CODEC’s, that seem to work very well for most users with many different MJPEG footage - Morgan Multimedia and MainConcept. These, however, are slightly generic, and might not work with a paticular camera mfg's. tweaked version. Always try to go to "the source," and install the version, that came with the camera. If you are editing footage from a camera, that you do not own, ask for the utility disc, that came with that camera, to get THAT version of the MJPEG CODEC.
If one has MJPEG footage (often in an AVI wrapper), they should investigate one of those two CODEC’s, after checking their camera’s utility disc.
For more background on file formats as “wrappers,” please see this ARTICLE.
For more background on CODEC’s in general, see please see this ARTICLE.
Hope that this helps,
As more camera mfgrs. seem to be using MJPEG (such as Nikon), they are tweaking the rather old CODEC, to improve it. Many cameras, that shoot video with the MJPEG CODEC are stills cameras, that also shoot video.
Below is a re-statement from above - but it is very important, and should be the first course of action, when confronted with the MJPEG CODEC.
In most cases, those mfgrs. are including THEIR version of MJPEG, with their cameras. Their customized version of MJPEG should be on a disc, included with their cameras, though it might not be straightforeward. Their version of MJPEG CODEC might be separate install, or might be installed as part of the camera's driver package, or might be installed with other software on that disc, such as a cataloging, or editing software program. It will depend on the exact camera, and model, but there should be a copy of their version of MJPEG, and that will always be better than a 3rd party version, that will likely be a generic MJPEG CODEC. Check the disc that comes with the camera, and install all software, even if one does not plan on using it to catalog, or edit the footage.