“Work principle
The code generates an analog signal using the internal DAC according to the PAL and NTSC standards described here.
Each image consists of two half frames (even and odd image lines). The blank level is at ~0.3V(values depend on PAL/NTSC). The synchronization is done using some pulses at 0.0V.
The following image gives an overview. Vertical synchronization is achieved by the purple pulses, horizontal by the red ones:”