NUM_PLAYBACK_URBS
for (i = 0; i < NUM_PLAYBACK_URBS; i++) {
for (i = 0; i < NUM_PLAYBACK_URBS; i++) {
struct urb *playback_urbs[NUM_PLAYBACK_URBS];
for (i = 0; i < NUM_PLAYBACK_URBS; i++) {
for (u = 0; u < NUM_PLAYBACK_URBS; u++) {