Hi.
The reason for the quality turning bad periodically is rather complicated and it is clear that many of these guys don't understand it fully. Some years ago I wrote in the wiki about this, where I go into much more detail on diagnosing and fixing the issue: Troubleshooting Streaming Problems
In your case, it happens when Blue Iris encodes a new i-frame in the video stream which it is sending to the mobile app or to UI3.
In most video you see on the internet, i-frames are very large (in terms of kilobytes) so that they do not cause a perceptible shift in quality. However Blue Iris encodes them relatively small, presumably so that they don't cause as much of a pause when the video stream is played with minimal delay. Or maybe it wasn't even a conscious decision by the BI developer. Anyway it is a tradeoff between quality and having smoother playback with low delay. Quality loses in this tradeoff. You can improve the situation by tweaking the encoding parameters, mainly by increasing the bit rate, but it is really easy to overcompensate (as seen in post #18 above). Ideally you should not turn off the bit rate limit as it could cause other issues with streaming to certain devices.
The reason for the quality turning bad periodically is rather complicated and it is clear that many of these guys don't understand it fully. Some years ago I wrote in the wiki about this, where I go into much more detail on diagnosing and fixing the issue: Troubleshooting Streaming Problems
In your case, it happens when Blue Iris encodes a new i-frame in the video stream which it is sending to the mobile app or to UI3.
In most video you see on the internet, i-frames are very large (in terms of kilobytes) so that they do not cause a perceptible shift in quality. However Blue Iris encodes them relatively small, presumably so that they don't cause as much of a pause when the video stream is played with minimal delay. Or maybe it wasn't even a conscious decision by the BI developer. Anyway it is a tradeoff between quality and having smoother playback with low delay. Quality loses in this tradeoff. You can improve the situation by tweaking the encoding parameters, mainly by increasing the bit rate, but it is really easy to overcompensate (as seen in post #18 above). Ideally you should not turn off the bit rate limit as it could cause other issues with streaming to certain devices.