DV4 CCTV file format conversion

by on under sysadmin
1 minute read

How I processed CCTV custom DV4 file format into MP4


  • I found my DVR required a FAT32 MBR formatted file system USB stick or USB HDD.

Part files

  • The files when exported from the CCTV will split at 2.1 GB into part files once the clip exceeds 2.1 GB in size.
  • You will need to reassemble them before making a MP4.
  • Turns out these can simply be concatenated together into one large blob: cat filename*.dv4 > filename.cat.dv4
  • Real example: cat CH04_2021JAN01000000_1.dv4 CH04_2021JAN01000000_1.part02.dv4 > CH04_2021JAN01000000_1.cat.dv4
  • VLC didn’t work on raw DV4 files. mpv does and so does ffplay.


  • After reassembling the part files you need to then do a container copy: ffmpeg -i filename.cat.dv4 -c:v copy -c:a copy -y filename.cat.dv4.mp4
  • Real example: ffmpeg -i CH04_2021JAN01000000_1.cat.dv4 -c:v copy -c:a copy -y CH04_2021JAN01000000_1.cat.dv4.mp4


Below is just a script to bulk process the concatenated files in a batch as it’s rather time consuming if you have more than one camera channel or date range exported.


for i in *.cat.dv4; do
		ffmpeg -i "$i" -c:v copy -c:a copy -y "$i".mp4
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