NETmc Marine Digital Video Systems

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High Definition Video

What is High definition ?

"HD TV or high definition television offers the highest picture quality available today. Instead of using the conventional 625 lines to plot a TV picture, HDTV uses 720 or 1080 lines. In addition, the pixels in each of those lines are closer together. This results in a hugely improved picture quality, clarity and colour definition. HD also uses millions more colours than SD TV, increasing the richness and intensity of everything you watch."

Why use HD video offshore ?

"The higher resolution video will allow the observer, rov pilot, dive supervisor etc to see more detail and make better judgements as to what is being looked at.

Are there any down sides ?

"Getting the HD video from the camera to the monitors at the surface may require a complete upgrade of the transmission system. The higher bandwidth of the cameras will require special cables, connector, multiplexors, distribution switchers etc. Most likely, the signals will switch from analog to being serial digital (SDI).

Also, data rates for the recorded video will be higher - so more storage will be required for the same number of hours of video. Typically (for compressed HD), between 5 and 10 times more data will be generated compared with SD video."

To make HD a realistic option for video archiving, NETmc Marine have come up with a good compromise.

Run HD cameras, fly ROV and observe using full res HD monitors, but record the majority of the archived survey material in standard mpeg2. We have found from trials and customer feedback that an SD recording from an HD camera still gives great quality - at a more realistic data storage level.

To demonstrate, we have recorded some test footage. The test was run with the same HD camera, transmitting its data via SDI. 2 different models of DVRi were recording the video - 1 unit recording in full HD mpeg2, the other able to switch between standard resolution mpeg2 (and even mpeg1).

The results are below for comparison. Please download the clips - if you don't already have any mpeg2 player on your computer, we recommend using Elecard, which can be found on our downloads page.