ADV7128 is a video DAC but can it be used to convert an audio signal in the
The ADV7128 is optimised for computer video graphics, although you can think of
it as simply a high-speed DAC.
The resolution is much lower than typical audio signals require (digital audio
is minimum 16 bits and usually 24 bits resolution while the ADV7128 is only 10
bits). Also, the DAC has a sampling rate very much faster than you require. So
overall the audio performance would be very poor.
However, the most important problem will be the format of your digital audio
input. You don't mention whether it is serial or parallel, or if it conforms to
a particular standard e.g. SPDIF, I2S etc etc. You will notice that the input
of the video DAC is 10 bits parallel so you would normally need to do some
digital reformatting of the data.