NTSC phase detection (allows 3D decoder to be used)

[eshaz]

Fixes

• Correctly detect NTSC chroma phase rotation sequence. This enables the use of the NTSC 3D chroma decoder for VHS and other color under sources.
  • The color burst phase is detected by converting each burst area into a complex signal (i.e. I/Q) and summing each burst's I/Q together for the entire field. The phase of the complex signal is measured and mapped to a quadrant which is used along with the isFirstField to select the correct NTSC phase rotation and field phase id.
• Limit track phase switching to the last 16 lines of a field.
  • False positives were very infrequently appearing in the middle of the field for noisy EP VHS recordings.