I recently bought a Samsung Smartcam, which in the booklet says it saves in JMPEG format ("video compression format H.264, MJPEG"), however when I open the files they have been saved as AVI, which my Mac won't open.
H.264 (MPEG-4 AVC) and MJPEG are two different methods for compressing video data. Both are playback compatible with QT. AVI is a file container. It is also compatible with QT under Yosemite. However, QT is not programmed to play AVI files that do not contain MJPEG compressed video with or without some form of PCM encoded audio. So the primary question here is "What kind of data is in the AVI container?"
Will I have to download a converter and convert all the videos I want to view, or is there another way? I looked at the settings on the camera and it doesn't give me an option to change the format.
Unless the device records both H.264 and MJPEG simultaneously and stores both to AVI files (which alone would prevent playback), there must be a setting, either built into the device or controlled by separate software, that allows you to switch between H.264 (in a different file container) and MJPEG in the AVI file container. I would recommend trying to open the file in a third-party player like VLC to see if the file will play and what kind of data formats the file actually contains. As to the conversion of data—that would normally be a last resort to be used only if necessary.
