-
I think for HDA there's two ways, either you feed in the i8253 signal into a pin on the codec, or the BIOS emulates the whole thing using an HDA widget to internally generate the tones inside the codec. I wonder if either or both of those approaches have band-limited output.
Well I just tried both on my laptop. Neither is bandlimited. The i8253 path at 10kHz (i8253 -> HDA codec PCBEEP input -> line out) has harmonics up to at least 290kHz before I hit the noise floor, and the internal gen at 12kHz (HDA codec beepgen -> line out) goes beyond 1MHz (!).pic.twitter.com/QroMccNeNk
-
-
Incidentally, that's 12kHz instead of 10kHz because the uber-crappy HDA internal generator works using an 8-bit divider from 12kHz (48kHz/4). Which makes PC Speaker music completely out of tune if played through it.
-
"Enh. Close enough."
- Show replies
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.