DM NetVu Observer

I have always found Dedicated Micros DVR’s (DM’s) pretty nice to deal with. When you are offered a multitude of ways to get the native video, there is rarely an issue if one of those options is broken (defective Optical drive etc). It’s after the Evidential Export that some problems can occur.

Netvu versionLuckily, DM also give us some help on what player is being used and this is especially helpful in this case as NetVu Observer utilizes Java. You may find that some of the older versions of the player have problems with the new Java update.

So, all the .Par files that need dealing with can play as expected within this player. The problem now is that there is a lot of unnecessary footage and whilst dealing with that we need to ensure that nothing is being altered.

File-Export

By selecting File > Export  – the box above appears. Initially this looks promising. Evidence disk creates a raw copy of what we have already and Video DVD is a built in Video DVD converter. These are both very handy in the right circumstances but I want to do a bit more to my DVD Copy. Due to this, AVI is my export of choice and after that I can assess what type of AVI its given me. The first issue with the player version detailed above is that the maximum avi time length that it could export was 15 mins.   There is obviously a problem with the AVI Export option as no error appears and the dialogue box states completed but the file is not what was requested!

Download Button

Under the Video display window, there is a Download Video Button (highlighted above). This is usually used when utilizing the software to recover video over a network. However, it also works for exporting video already recovered.

Download Video

This brings up the box above which is slightly different from the initial export box. In order to create the .avi files, the software creates temporary .par files consisting of just the footage you request in the time period input boxes. It is handy to change this to somewhere more accessible as you may want to save this. Then, after selecting the cameras of choice, the .avi export works!

We now have a number of avi wrapped video files, one for each camera selected. I requested exactly 1 hour…

Duration : 1h 0mn
Duration : 1h 0mn 16s 280ms
Duration : 1h 0mn
Duration : 01:00:16.280
Frame rate : 25.000
Frame rate : 25.000 fps
Frame count : 90407
Resolution : 8
Resolution : 8 bits
Color space : YUV
Chroma subsampling : 4:2:0

As you can see from the mediainfo report, I have a video that is reporting an extra 16secs and 280ms…… this is something to be aware of!

Although this is a format known to me I quickly had a look at the original .par files within Hxd and confirmed that I was dealing with MotionJpeg streams. Various different formats could be wrapped up inside the PAR files so its always worth checking. Most now utilise H264.

Hex-par

The nice thing with these is that each image is referenced with their associated timecode and this is detailed after the Frame number and jpeg header. By checking these on the temporary produced Par files I could see that the last image recorded was 16s 280ms over the 1hr mark. Keeping this file in Hxd and then dropping in one of the avi files I could compare and verify these were just avi wrapped motion jpeg streams and each image was the same bit for bit.

Looking within mediainfo again, I could establish certain other details:

Width : 704
Width : 704 pixels
Height : 256
Height : 256 pixels
Pixel aspect ratio : 0.500
Display aspect ratio : 1.375
Display aspect ratio : 1.375
Frame rate : 25.000
Frame rate : 25.000 fps
Frame count : 90407

The interesting thing here is that there are 90407 frames and at 25fps……. however when I look at the .avi in Virtualdub, there are a large amount of duplicate frames.

Dealing with these can be done in a number of ways.

As they are MotionJpeg avi’s, you have the option of using JpegSnoop. This will scan the file and extract each jpeg from within the file. It also keeps each jpegs metadata (the specific date / time etc).

Another way is FFmpeg. The command:

ffmpeg (input.avi) -vcodec copy -vsync drop (output.avi)

…. results in a motionjpeg file of all unique frames and no duplicates. Its also very fast. There are a number of benefits in doing this but the main one is that when reviewing frame by frame, you don’t have to deal with the duplicates that are created in the original avi export. Each jpeg remains intact with the important metadata.

Using both methods resulted in 2631 frames.  As we have a start time (from the first frame) and the end time (from the last frame) it’s now possible to establish the frame rate and, if required,  re-do the FFmpeg convert to add in the -r command to enter a specific frame rate. (0.72 FPS).

For grabbing frame images or review, Virtualdub or Forevid work great.

For creating a presentation multi-camera Video DVD, I found that by dropping the image only avi’s into Edius and then adjusting their duration / speed, resulted in easier scrubbing whilst editing. They also had to be re sized within the NLE to deal with the 704 x 256 field based recording.

At least this way, I can monitor any changes to the images throughout the workflow and utilize the produced files for numerous uses.

If you want to dig a little deeper and analyse the specific time-code for each image, take a look at this entry, in particular the details at the bottom.

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3 comments on “DM NetVu Observer

  1. Pingback: Dedicated Micros PAR files | Spreadys.com

  2. Pingback: Dedicated Micros DAT Files | Spreadys.com

  3. Pingback: Corrupted DM Files – Amped FIVE to the Rescue | Spreadys.com

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