Failure to handle NTSC frame rates is exactly why no one uses a time definition like this. ISO/MP4 gets it right: Using a time scale with sample durations. If y

Failure to handle NTSC frame rates is exactly why no one uses a time definition like this. ISO/MP4 gets it right: Using a time scale with sample durations. If you work with tracks or files with different time scales you just use the smallest common multiple of those to become your working time scale. Works every time, even for NTSC frame rates. For instance for a file with 48Khz sound and 30000/1001 (29.97...) frame rate you would convert to a time scale of 48048000. Worst case would be mixing 48Khz, 44.1Khz and NTSC video: 1009008000.