There are two factors that effect the Frame Rate: Computing Power and Exposure Settings.
First of all we should know how to monitor the frame rate. The frame rate can be monitored in several ways:
- Through MxCC: select the live stream of one camera and check the status bar
- Through MxEasy: make sure to display the live view of one camera in the focus window and check the top-right corner
- Through the camera live image: go to “Setup > Text and Display” and type the following string in the text box: Frame Rate: $(IMG.FRJ)
Computing Power
Image Resolution:
The higher the resolution, the higher the amount of information that has to be processed. It is recommended to sacrifice the resolution of the Live Image, in order to free up the processor for the recorded image. The logic being that the recorded images are presented to Authorities, as evidence of an event. Therefore, far more important then the live image.
As each camera configuration is unique, it is impossible to provide definitive values. As a result, you will need to test and adjust the resolution to find the optimal balance. To change the live resolution go to “Setup > General Image Settings”.
Number of sensors displayed:
If you have a dual lens camera and you want to display both sensors at the same time the frame rate is going to be drastically effected. To change the display settings go to “Setup > General Image Settings”.
Image Quality:
It’s the number of pixels that the camera actually reads from the image sensor. We can choose between three different levels: “High” means that all the pixel are read, “Normal” means that only 75% of the pixels are read whereas “Low” means that only 50% of the pixel are read. All the “non-read” pixel will be interpolated which means that the camera will use an algorithm to guess their values according to the surrounding pixel. Therefore higher the image quality the lower the frame rate, as more information needs to be processed. You can set it from “Setup > General Image Settings”.
“Normal” is generally a good compromise to get a good frame rate and a fair image quality.
JPEG Quality:
It indicates the inverse ratio of the JPEG compression. In other words the higher the JPEG quality You can set it from “Setup > JPEG Settings”.
JPEG Quality of 60% provides a good balance between quality and frame rate.
Video Codec:
MxPEG is a proprietary MOBOTIX codec. It optimized to deliver the highest image quality possible without drastically affecting the frame rate. It achieves this by transmitting only the differences between sub-sequential frames. You can set it from “Setup > JPEG Settings”
Full Image Recording:
It is a feature that allows MOBOTIX cameras to record at a different resolution (typically higher) than the live view. The best performance in terms of frame rate can be obtained when the Full Image Recording is switched off.You can check it from “Setup > Recordings”.
Video Image Analysis:
Video Motion and MxActivitySensor require a significant amount of computing power. It’s better to deactivate the video analysis if not needed.
NOTE: In dual lens cameras there is an option called “Dual lens Video Motion“. If enabled it will force the camera to process the streams of both sensors and the final effect on the frame rate is the same as displaying two sensors in the live view.
Exposure Settings
Exposure Time:
The main objective of MOBOTIX cameras is to deliver images with the best quality possible. The camera can compensate for a lack of illumination by increasing the Maximum exposure time. This increases the amount of light that enters the sensor. Although this is important to get good quality video, long exposure times strongly affect the frame rate. However it’s possible to set a limit to the Max Exposure Time from the page “Setup > Exposure Settings”.
An Exposure Times of 1/30 sec provides a responsable balance. This means that the camera will never use exposure times longer that 1/30 even, in less then ideal lighting conditions.
It may be interesting to display both the illumination level detected by the image sensor and the exposure time selected by the camera. To do that go to “Setup > Text and Display” and type the following string in the text box: Illumination Right: ^IR Exposure Right: ^ER Illumination Left: ^IL Exposure Left: ^EL
Image Programs:
Image Programs are a collections of presets that allow the users to speed up the process of configuration of image and exposure settings. To select the program that better matches your needs go to the Live View, open the central drop-down menu and select “Image Program”. Select the program from the drop-down menu on the right. A pop-up window will list all the changes that are going to be . As you can see the Image Programs will modify some of the parameters aforementioned.
3. Conclusion
The logic is that Frame Rate and Image Quality are inversely proportional to each other. Meaning: you cannot get a very high frame rate and very high quality images at the same time. You need to find the right compromise.