Please lower the bitrate and see if more pulsating pixels arrive. Tell me the response.
I am 99% sure that the behaviour you see is not pulsating. Its just encoder placing I frame over P frames - this is normal in H264 because this is how H264 works.
Stream is divided into I frames and P frames (and sometimes Bframes also). Structure is as this: I P P P P P I P P P P I P P P P
In simple explanation (really) - I frame is IDR frame (IDR - Instantenous Decoder Refresh). I frame is a complete ONE frame like JPEG image.
in 25 fps and keyframe interval set to 25 you will recive one I frame every 24 FPS (24+1) - This 24 fps are just DIFFERENCES between movement in time.
After 24 FPS when next I Frame arrives - it will clear the buffer of decoder and place on complete frame in front of you and again over this IFrame - place next comming P frames (differences). This is the moment you see pulsating. Because the encoded compelte frame differs than the already buffered video (it has to, it's nature of lossy compression).
Now imagine you set bitrate of 2Mbps on FULL HD resoltiuion. Now get a snapshot of one frame. Place it on you image editing software and lower the quantization level to acquire 256 kb image size (2Mpbs = 256 kbytes of data). You will se quality degrading. and know that this 256 kb of data has to fit in one second of video. So 256 kbytes will have on I FRAME (one JPEG image) and 24 P frames (differences). It has to fit somehow. So encoder degrades quality.
Normally you wont see this hapening (high bitrate and good light conditions). But when sensor is small and produces a lot of noise (yes, noise like in simple DSC) you will see pixels pulsating. Its just noise on sensor which encoder sees as a object movent in time. If so, then it lowers IFRAME quality to fit also P frames in this second of stream.
Thats why bigger sensor means better light gathering and better quality (pixels on sensors are bigger so can catch more light). But bigger sensors i mean sensor size like 1/2.8 inch or 1/2.5 inch. Anything like >2Mpix and sensor below 1/2.8 (1/3 etc) is a complete useless. Because it will only work in good light and very good light. Forget about low light in such small sensors. Thats why buying 4Mpix Hik with sensor size 1/3 inch is not good idea.
Check Sony VB635 which has only 2Mpix but sensor size 1/2 inch in low light - you will se the difference.
Also thats why cheap cams implement tons of functions called DNR/3DNR/2DNR and other shit - it's all about blurring those noise from crappy sensor in low light.
