Does the camera come with its own software? My Canon also used the Motion JPEG format that your camera seems to use, though it produces them in AVI format. Still I recall VLC being able to play them. I also know that my Canon comes with software that not only plays them but edits as well, hence my suggestion to see what the manufacturer offers.
The suddenly going black business does not sound good and I wonder if they were corrupted prior to copying?
I don't think this Panasonic camera has its own software (ie not like Canon does). It's not my camera, I'm asking this question on behalf of the camera owner. The latter filmed other sequences on the same memory stick, which have not 'gone black' and can be read OK on my Mac. The camera owner swears that just after shooting she showed the sequences to someone on her camera screen successfully just once, but was not able to give any repeat viewing. On my Mac, the (presumably) corrupted .mov files still show as 700Mo and 300Mo, but with 0.00 duration.
Many thanks for your help.
Examine the file in Terminal or with a hex editor.
Assuming you use Terminal and have a file on the Desktop named test.mov, this Terminal command will display the first line of that file:
head -1 Desktop/test.mov
A valid file will begin with a header that identifies the file type. It will look something like:
ftypqt qt moovlmvhd . . .
If you also have a valid, working file from that same camera, you could compare the headers of working and nonworking files to see whether they're similar.
On the other hand, if the file is damaged, often the header will be missing or corrupt. If it's corrupt, you'll probably see that the file starts with an indecipherable data stream along these lines:
Although there are services/software* that will try to repair such files for a fee, as far as I know, there's no easy, free solution to resurrecting a corrupt file.
When the user first saw the movie on display in her camera, I would guess that she was viewing data that was still stored in the camera's internal memory. Then something went awry as the camera moved the contents of internal memory to the memory card.
The card itself may also be failing. Before using it again, I'd use the camera to reformat it. The camera-reformat process should identify any bad sectors and prevent them from being used again. Then, if the problem recurs, I'd recommend getting a new memory card. Or, to be safer, get a new card now. No one should risk losing data because of possibly flaky $10 storage media.