Compression is very important. While resolution gets the attention, compression is critical and can be a silent killer - both for quality and bandwidth.
Regardless of resolution, all surveillance video is compressed. And even if 2 cameras have the same resolution, their compression levels can be much different. [See our compression / quality tutorial for background.]
Thankfully, compression in H.264 is standardized on a scale of 0 to 51, as shown in the image below:
However, camera manufacturers almost never disclose Q levels used. Instead, they use a variety of homemade scales and naming systems. Here is a sample of ones we tested inside:
So you can have 2 manufacturer's cameras with the same resolution but significantly different compression levels, and therefore varying image quality and bandwidth consumption.
An industry first, IPVM has analyzed each of these manufacturers and answered these key questions:
- What is the real H.264 quantization level for each camera manufacturer's default settings? How do they vary? Who defaults the lowest and highest?
- To normalize the H.264 quantization levels so that each manufacturer had the same compression, what camera settings should be used?
- How does the range of compression levels used for each manufacturer map to H.264 quantization levels?
- What is the impact of bandwidth as H.264 quantization / compression levels are varied for different manufacturers?
If you really care about image quality and optimizing bandwidth / storage use, this is a critical report.