Method and apparatus for determining type of video signal to be output

An apparatus for determining a type of video signal to be output comprising:

• three digital-to-analog converter (DAC) ports of a set-top box, wherein the set-top box comprises multiple different video interface modes, wherein one of the different video output interface modes uses the three DAC ports to output a luminance, blue color difference, and red color difference (YPbPr) video signal, wherein another one of the different video output interface modes uses the same three DAC ports to simultaneously output a luminance and color (YC) video signal and a composite video broadcast signal (CVBS) video signal, wherein a detection signal is output in the one of the different video output interface modes using one of the three DAC ports, wherein the set-top box is switched from the one of the different video output interface modes to the another one of the different video output interface modes, and wherein additional detection signals are output in the another one of the different video output interface modes using two of the three DAC ports;
• a detection signal extracting module configured to extract the detection signal and the additional detection signals in the different video output interface modes, wherein the detection signal and the additional detection signals have different constant voltage values before and after a corresponding one of the three DAC ports is connected to a load;
• a converting module configured to convert the extracted detection signal and the additional detection signals into direct current voltage signals;
• a voltage comparing module configured to compare each of the direct current voltage signals with a voltage threshold to determine whether each of the direct current voltage signals is greater than or less than the voltage threshold;
• and
• a result determining module configured to determine a type of video signal to be output based at least in part on which one or more of the direct current voltage signals is greater than the voltage threshold,
• wherein the voltage comparing module is further configured to:
• record a zero value for one of the three DAC ports when the direct current voltage signal is less than the voltage threshold;
• and
• record a one value for the one of the three DAC ports when the direct current voltage signal is greater than the voltage threshold, and
• wherein the result determining module is further configured to perform an “OR” operation on recorded one and zero values for each of the three DAC ports to determine the type of video signal to be output.