title: Is it legal to have inconsistent frame rate in an mp4 (h.264/avc) video
body: <p>I am constructing a video from a content that doesn't change at a constant rate (phone screen virtual display), in fact I receive frame only when there is such a change. Is it legal according to the standards to have inconsistent frame rate in a video? For example have frames with PTS of 0s, 0.066s, 0.1333s, 0.2s and then the next frame at 20s, etc?</p>
  
  <p>It seems some players (Chrome) are struggling playing it back correctly, when encountering such a time gap, it sometimes start showing frames from the beginning of the video instead. Should I replicate the last frame myself to maintain a constant frame rate? Is there a way to instruct a codec (ffmpeg) to inject "skip frames" at a constant rate when such gaps are detected.</p>
  
  <p>Thanks</p>