fsphil
Vertical Interval Test Signal (VITS)
This ticket is made to suggest adding vertical blanking test signal (VITS) used to calibrate the image brightness, color, setting proper gain and troubleshot transmission problems.
Some docs here:
https://www.semanticscholar.org/paper/Current-Usage-of-Vertical-Interval-Test-Signals-in-O'Connor/bc793d1eac9efbc02faf1596bde664c5c5d6d426
https://www.tek.com/datasheet/vm700t-option-11
Interlaced snapshots captured from my VHS tapes:
RTL7 example:
Zoomed lines - 37, 38, 39, 40
Canal+ example (with nagravision signals too):
Zoomed lines - 37, 38, 39, 40
TVP2 example:
Zoomed lines - 40, 41, 42, 43
Zoomed lines - 40, 41, 42, 43
TVP1 example:
Zoomed lines - 41, 42, 43, 44
Discovery Channel example (with videocrypt signals too):
Zoomed lines - 41, 42, 43, 44
Some more information on these test signals: http://zone.ni.com/reference/en-XX/help/373389B-01/nivms/pal_patterns/ https://www.itu.int/rec/T-REC-J.61-199006-I/en
They occupy lines 17, 18, 330 and 331 on PAL systems (and I presume SECAM as well). I will add these but not just yet, I'm busy with another project right now. Assigned to myself.
My first go at a VITS generator is now committed. Use --vits to enable.
The phase of the chrominance signals are going to be wrong, and it's not supported on 525 line modes yet. I'll leave this issue opened until those are resolved.