Shield for Arduino based on the integrated LM1881 (National Semiconductors) which allows to add text to the composite video signal (PAL and NTSC). The IC LM1881 allows to extract the sync information present in the PAL and NTSC composite video signals. To use the shield with Arduino is available the TVOUT library that greatly simplifies the writing of the code. Arduino manages the vertical sync signal output, the video signal input and output, the sync signal in the composite video output. A trimmer is connected to the analog input A2 that allows you to calibrate the brightness level to use as a cutoff point when capturing video frames. The jumper SYNC (SYNCSELECT) allows you to choose the source of the synchronization pulse of the video signal. Normally this is used in the pulse input video signal. However, you can use the circuit without an input video signal generating software from the sync pulse on pin 9 of Arduino. The switch SW1 (OUTPUT SELECT) allows you to set the behavior of the shield with respect to the different ability to overlay text to the video signal. The various options are: Outgoing presentation of the text superimposed on the images, presentation output of only the pictures, presentation output text only. Clearly the possibilities described must be compatible and consistent with the overall system configuration, you can not, for example, select the output images only mode if the input is not a video source. 

This project comes in kit. Some components have to be soldered to the included PCB.