539: interframe interval = 1/25.28 s  avg=1/28.02  stddev=1/65.18
  539: interframe interval = 1/33.45 s  avg=1/26.97  stddev=1/63.06
  539: interframe interval = 1/29.06 s  avg=1/27.67  stddev=1/62.13
  539: interframe interval = 1/36.02 s  avg=1/27.91  stddev=1/65.83
  539: interframe interval = 1/33.22 s  avg=1/27.08  stddev=1/60.85
  527: interframe interval = 1/38.89 s  avg=1/27.90  stddev=1/61.51