Memory array to pio using DMA (Video)

That's correct, the standard DMA will stop after the transfer is complete and so in order to avoid underflowing you would need to have it operate faster than the DAC rate and ensure there is enough buffering to compensate for the time taken to get the DMA started again. Typically you use something like the scatter-gather DMA that can coordinate multiple frame transfers without software intervention.

In that design I pointed you at this is all taken care of in the hardware. The video frame descriptors are tagged with a 'park' bit which means the same frame keeps getting displayed until you provide another frame. So you would just connect the ST data up to your DAC, hardcode the ST ready signal high, leave the valid signal as a no-connect, and use your DAC clock to clock the mSGMDA (or put a clock crossing FIFO in between if you want the DAC and mSGDMA domains to be different).