Subject : ADV7842 failes to detect NTSC on CVBS with certain pattern.
Symptom : Confueses NTSC as SECAM with 1-px frame pattern.
Without 1-px frame, it works properly.
With 1-px frame, it losts burst lock and detect as SECAM.
Disable SECAM from auto detection lists
SMPTE 170M Composite Video Signal