Bugzilla – Bug 388
Mac: Recording Preferences has an unsupported "Hardware Playthrough" option
Last modified: 2018-08-20 11:45:15 UTC
The "Thru" box in Apple Audio MIDI Setup which our Preference is meant to control is greyed out on all known Macs on all supported versions of OS X (10.4 +). Clearly the presence of the preference wastes user and support time, but should the code be ripped out or only disabled? Why doesn't Apple remove the "Thru" checkbox?
Definitely remove it. It hasn't worked in years. Actually, as long as I've been fiddling with Audacity, I've never seen it work.
Rather than simply remove Hardware Playthrough from Recording preferences, I think the more conservative thing to do is make the preference false, and disable the checkbox control, if the API tells us it is not available. To do this, I strayed into changing portmixer, to make a more correct test of whether hardward playthrough is really supported on the system. But portmixer is also "ours," sort of? (It's Dominic and Roger's work.) I also see that calls to AudioDeviceGetProperty are flagged by XCode as deprecated. Would a rewrite of PortMixer to use recommended functions discover how to play through for real? I hesitate to push this fix to master. Someone might want to review it. Most likely that is for Leland, but I have not heard much from him lately. So I leave my fixes here: https://github.com/Paul-Licameli/audacity/commit/03e4fccdcc204a87e50f03e7b8a0dcbadb2ea574
(In reply to Paul L from comment #2) The only information I can find about this online https://discussions.apple.com/message/8083035#8083035 from an Apple forums responder with > 28000 points says: "Thru" is only for external audio devices with hardware audio pass-through. Built-in Audio Input does not support it. That means I believe that the built-in input did not support it after OS X 10.3. Presumably with your suggested changes, Paul, you did not get Hardware Playthrough detected on your Mac? In principle I agree with Paul's more conservative approach but I have no idea what external devices will support it. Added "git" keyword.
RM deciding not to use the suggested fix in 2.1.3. Reason is it involves changing portmixer, and that should happen upstream. Also Paul is perfectly able to commit this when/if he thinks it is ready/suitable, and I think his judgment not to (yet) is right.
*** STEPS UPDATED *** Also promoted from P3 to P2. RM should decide on it going through to release. DEVEL - FIX MADE https://github.com/audacity/audacity/commit/7a5bbbcce86a279a2de63316e909540158b64e66
(In reply to James Crook from comment #5) Testing on eee58d9 06Aug17 on macOS Sierra 10.12.6 In the Recording preferences dialog there is no longer a "Hardware Playthrough" option, only a "Software Playthrough of input".
(In reply to Peter Sampson from comment #6) I updated the Manual accordingly: http://alphamanual.audacityteam.org/man/Recording_Preferences
