Bi,

The mts or m2ts extension is the camera format, normaly  mts référence to the first génération raw camera format and after import in your computer this becomes the second génération m2ts extension.  normally we generate and export format with a software this is a MP4 format différent size like1920 x 1080 or 1280 x 720 for HD  and 854 x 450 for SD vidéo. 

Regards,

YR

Hi

To expand YR's post -

The mts and m2ts are MPEG Transport Stream container files, more often known as AVCHD video, which can contain mpeg2 or H.264 encoded files - they are a common file format for many HD video cameras in particular Sony and Panasonic . To all intents and purposes they are the same.

Files on a BD disc have the m2ts file extension as specified in the standard for Blu-ray discs.

The mp4 is also another file container format that can also contain video encoded as mpeg2, H.264 and other encoding formats. They are also a common format for many HD video cameras.

MP4 files are suitable for putting on websites because they can be made streamable - ie they will start playing without having to download the whole file first.

Both formats offer high quality HD video in relatively small files sizes, however they are processor intensive when creating or playing back on a computer.

. . . . When I go into file menue, export movie video as MPEG4, when the film is finished the ext says m2ts. . . . .

That is because you have selected an AVCHD preset for MP4 you select one of the HD TV presets - if you look in the pane where the destination folder location is you will see the file extension that is being used.

HTH

John EB