What is normally a quick and easy job can turn into a lengthy process when the exported video from a DVR suffers with errors.
I have a number of posts all relating the exports from Dedicated Micros DVR’s in DAT and PAR Containers.
For reasons unknown at this time, the file in question here would just not play ball!
It would crash Netvu Observer and various versions were tested. It crashed the PAR File Copier software that can be used to rewrap streams and demux camera’s. Upon hex level review the jpeg based format was identified and they could all be identified and extracted using Jpegsnoop (as detailed in the DAT Post hyperlinked above). Usually this would then just be a case of decimating by the amount of streams and creating the single camera file in Virtualdub. The problem with this file though was that the camera order kept on changing.
I could have done it manually, for all streams but I needed it done ASAP.
Amped FIVE has a very powerful demultiplexer. Multiplexing devices hark back to the Analogue days of huge camera input boxes feeding a single feed out, and into a VHS deck. The skills learnt from VHS demultiplexing though are used regularly with Digital files and streams.
After opening FIVE, I loaded in my image sequence that had been extracted from Jpegsnoop:
This loads all the images as video frames, but as we already know, there are many different views/cameras and they are not in a set order. Time to demultiplex
The Demultiplexer has a sensitivity setting which dictates the level of difference in each scene, known as the threshold.
After adjusting my threshold a couple of times, my camera / scene amount was correct and I could move through my cameras correctly, with the correct frame count for each one seen at the bottom.
At this point I could have conducted any clarification or image enhancement required but for this purpose I finished off by correcting the aspect ratio. I Didn’t use the Resize Filter as this applies interpolation to all lines. Instead I used the De interlace Filter with the Same Field parameter. Thanks to Martino at Amped for pointing me in the direction of that one.
Don’t you just hate field based recordings!
Lastly it was over to the Video Writer to save my Cameras streams.
I hope this shows that a manual extraction, reordering and rebuilding is quite possible, but dedicated software can take a lot of the pain and time away.