I recently bought a Panasonic HC-V750 camcorder and I was intrigued by the additional files (.cont, pmpd and .tmb) it produces along with the video files – do they contain useful additional data?. A good googling didn’t turn up anything useful but a lot of people have wondered about them.
The first one to discuss is the .pmpd file as the contents of this are XML and therefore easy to read. I don’t claim to understand what all the values mean but it’s clearly showing the camera settings when the clip was recorded (for example was face recognition switched on). The bundled HD Writer software might be able to read this but I doubt anything else does.
The next file is the .tmb file. This is in a binary format so I had a peek inside with HxD, a hex editor. My guess is that “tmb” is a shortened version of “thumb” since this file appears to mostly comprise a couple of thumbnail images but there is probably some other metadata in there as well. The file starts off with the regular “exif” characters “ÿØÿá” or better displayed in hex as “FF D8 FF E1” so this is probably a standard exif file and could be read with an appropriate reader. I believe the thumbnail sections start “456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz” since a googling for this turns up a fair number of discussions about images.
The last file .cont was the one that intrigued me the most as it seemed to be important for HD Writer but it turned out to be rather dull. My guess is that this is the file HD Writer uses to identify files that need to be stitched together. The file starts by indicating what it is then there’s a chunk with no data and it finishes up by listing the names of all the files that make up the clip along with the metadata files. If you delete these metadata files then HD Writer won’t even look at the clips but my guess is that it’s reading this file. With some effort I think would be possible to recreate this file by hand. I tried copying and renaming a .cont file for one clip over the .cont for another clip, HD Writer then displayed the wrong thumbnail and played the wrong files for the clip. This failure is almost certainly because I didn’t change the file names at the bottom of the .cont file.
Anyway, I went digging in these files because I was suffering from the lost audio problem when recording long clips that span more than one file. I had hoped to find the missing audio data in one of the additional files but I know it was a long shot. For my next trick I’m going to try to reverse engineer the remote control software for the camera.