Hi Sarit, the AXIS models used were: P1347, P1346, M5014, M1054. Sharpness was left at its default (i.e., 50) and VBR was used. A max shutter speed of 1/30s was also set during our experiment.
It's a bit hard for me to chart both frame rate and compression level on the same graph. The way they should be understood although is as follows:
1) Frame rate graph
A max frame rate of 25 FPS was used in our experiment (our basis for comparison). Therefore, to show how much bitrate can be reduced by decreasing the frame rate, we considered 20 FPS, 10 FPS, 5 FPS, and 1 FPS as well. We then compared how great (in terms of percentage) the reduction was. The result was 20%, 60%, 80%, and 96%, respectively. It is important here to mention that independent of the compression level used, the same reduction was observed. For example, by reducing frame rate from 25 to 1, a reduction of approximately 96% was observed in all IP cameras tested and proportionally to the compression level used in both FPS. That is, a very high compression level with a frame rate of 25 FPS was compared with a very high compression level with a frame rate of 1 FPS; a high compression level with a frame rate of 25 FPS was compared with a high compression level with a frame rate of 1 FPS, and so on.
2) Compression level graph
A very low compression level (equivalent to the AXIS compression value of 10) was used in our experiment (our basis for comparison). Therefore to show how bitrate can be reduced by increasing the compression level, we considered low (30), medium (50), high (70), and very high (90) compression levels as well. We then compared how great (in terms of percentage) the reduction was. The results vary depending on the CODEC used. M-JPEG streams profit considerable more than H.264 streams. It is worth here saying that you should not view this graph with the FPS being constant at 25 FPS. You should see as follows: when the compression level is increased from very low to low, for instance, a reduction of approximately 28% (H.264) and 47% (M-JPEG) is observed independent of the frame rate used. That is, these percentages were observed independently whether the frame rate was 25 FPS, 20 FPS, 10 FPS, and so on.
Should you be interested in knowing more details, I can send you the Excel sheet with my calculations for your better understanding.