Seems stream 0 codec frame rate differs from container frame rate: 30.00 (30/1) -> 15.00 (30/2)
Input #0, mpegts, from 'somefile.mp4':
  Duration: 00:01:30.49, start: 48670.015956, bitrate: 843 kb/s
  Program 1
    Stream #0.0[0x44](): Video: h264 (High), yuv420p, 800x600 [PAR 1:1 DAR 4:3], 15 fps, 15 tbr, 90k tbn, 30 tbc