FlyVision CarCam Video Files Extraction

Unlike most of the carcams, whose recorded video files reside in FAT or FAT32 formatted partitions, FlyVision carcams (飛來訊行車記錄器 FDV-606 in this case) store the video data in proprietary format.  Running the utility (FlyVision.exe, a Win32 executable. What the ...) came within the memory card seems the only way to access those video files.  Let's see what we can do on our Linux box. (Tried WINE with no avail though.)

The SD card capacity is 4 GB but from the mount point shown below we found only 120 MB is claimed, which implies the rest of the space is occupied in a non-standard, proprietary way.

$ dmesg | grep sdb
[509.440609] sd 6:0:0:0: [sdb] 7759872 512-byte logical blocks: (3.97 GB/3.70 GiB)
[509.441822] sd 6:0:0:0: [sdb] Write Protect is on

$ df -Th /media/DR_DISK

Filesystem    Type    Size  Used Avail Use% Mounted on

/dev/sdb      vfat    120M  816K  120M   1% /media/DR_DISK

First of all, we dumped every single bit from within the SD card (/dev/sdb in our case) to our local hard drive, say dump.dat, for analysis by running:

$ sudo dd if=/dev/sdb of=dump.dat

As expected, almost 3.8 GB of image was dumped with file information below:

$ file dump.dat

dump.dat: x86 boot sector, code offset 0x3c, OEM-ID "S&Q TECH", sectors/cluster 32, root entries 512, Media descriptor 0xf8, sectors/FAT 30, heads 255, sectors 7759872 (volumes > 32 MB) , reserved 0x1, serial number 0x0, label: "SQFSFATDISK", FAT (16 bit)

From the exported file of FlyVision GUI, we can see the file extension used is .AVI, which was actually defined in RIFF specification designed by Microsoft.  In the hex-mode editor, luckily we found the file magic number - the string "RIFF" (w/o quotes).  A brief version of RIFF spec follows:

offset size description

-----------------------------------------

0x0000  4   magic "RIFF"

0x0004  4   size of data that follows, N

0x0008  N   N-byte data

Further analysis showed all the .AVI files were stored continuously, therefore it's very likely we could extract the files from the big chunk without too much hassle.  The original video file names were also seen not far from the first .AVI file magic pointer, but for code simplicity we discarded this information and use our own naming convention - extracted-###.avi.

08078000   50 49 43 54  30 30 30 31  41 56 49 20  00 00 00 00  PICT0001AVI ....
08078010   00 00 00 00  00 00 00 00  00 00 03 00  00 00 00 08  ................
08078020   50 49 43 54  30 30 30 32  41 56 49 20  00 00 00 00  PICT0002AVI ....
08078030   00 00 00 00  00 00 00 00  00 00 03 10  00 00 00 08  ................
08078040   50 49 43 54  30 30 30 33  41 56 49 20  00 00 00 00  PICT0003AVI ....
08078050   00 00 00 00  00 00 00 00  00 00 03 20  00 00 00 08  ........... ....
08078060   50 49 43 54  30 30 30 34  41 56 49 20  00 00 00 00  PICT0004AVI ....
   :
   :
   :
08080000   52 49 46 46  F8 FF FF 07  41 56 49 20  4C 49 53 54  RIFF....AVI LIST
08080010   E0 01 00 00  68 64 72 6C  61 76 69 68  38 00 00 00  ....hdrlavih8...
08080020   35 82 00 00  00 00 00 00  00 00 00 00  10 00 00 00  5...............
08080030   F1 0D 00 00  00 00 00 00  02 00 00 00  00 40 1C 00  .............@..
08080040   00 05 00 00  E0 01 00 00  00 00 00 00  00 00 00 00  ................
08080050   00 00 00 00  00 00 00 00  4C 49 53 54  04 01 00 00  ........LIST....
08080060   73 74 72 6C  73 74 72 68  38 00 00 00  76 69 64 73  strlstrh8...vids

With some tests and tuning, we came up with a one-liner which extracts all .AVI files found in the image dumped.

$ grep -aboP "RIFF....AVI" dump.dat | perl -ne 'if (/(\d+):RIFF(....)/){ system "hexdump -s $1 -v -e " . qq("/1 \\"%c\\"" -n ) . (8+unpack("V", $2))." dump.dat > extracted-". sprintf("%03d",++$i) . ".avi"; }'

Few minutes later, 28 .AVI files with total size of 36 GB were successfully extracted.  Mission complete.

$ ls -l extracted-02*.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:52 extracted-020.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:52 extracted-021.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:52 extracted-022.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:53 extracted-023.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:53 extracted-024.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:53 extracted-025.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:54 extracted-026.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:54 extracted-027.avi
-rw-r--r-- 1 almond almond 134217728 2012-05-05 14:54 extracted-028.avi

$ file extracted-016.avi
extracted-016.avi: RIFF (little-endian) data, AVI, 1280 x 480, 30.00 fps, video: Motion JPEG, audio: (mono, 16160 Hz)
 

Screenshots of video playback: