leeton Left and Right Channel of audio outputs sampling at the same time?
yes.
leeton Is it possible to know the time delay between the audio output and the DAC0?
This is a bit complicated. It will be about 21+1 samples because of the group delay of the DAC of the codec and the bus transmission. Also, this cannot easily be measured from the PRU as we did above, because, while the analog DAC/ADC are written/read exactly when the code is executed on the PRU, the audio DAC/ADC come and go to a different chip (the codec), and there they are written/read synchronously with the codec's own clock.
The easiest way of measuring the offset between the audio and analog DAC is therefore to write the same signal to both (e.g.: a 1-sample impulse) and measure on the scope the time difference between the two.