I have set up Security Monitor Pro with 4 IP cameras and configured it to play an alarm on motion detection. I found that some of the time at night, the alarm gets turned on from my garden camera. What could be the reason? How can I reduce these alarm events?

I am using Text Speaker to convert an E-book into a MP3 file. The output MP3 file size is too large. How can I reduce the MP3 file size?