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admsyn / ofxAudioUnit

An openFrameworks addon which makes it easy to work with Audio Units on OSX and iOS
MIT License
120 stars 24 forks source link

File player does not currently support pause / resume #8

Closed admsyn closed 10 years ago

jasonlevine commented 10 years ago

Can setting a position in the audio track (in ms or samples) be added to this issue? I'd be glad to help if you could point me at some good examples/resources. Thanks

admsyn commented 10 years ago

Can setting a position in the audio track (in ms or samples) be added to this issue?

Sure can :)

The implementation for this is more tricky than it'd seem at first. There's some low level concerns RE: host times and scheduled play back times and sample frame times and blah blah blah to be navigated, which is proving to be a bit tricky.

I've got the gist of it working on this branch (fileplayer-pause-resume). It seems to work just fine for the initial pause / resume, but subsequent attempts end up resuming at the wrong point in the file. This post on the core audio mailing list makes it sound like that's more-or-less expected behaviour, since it sounds like the code needs to take the host time into account when setting the kAudioUnitProperty_ScheduledFileRegion property, and apply the timestamp.mSampleTime offset to that.

Or something.

Audio Units, man.

admsyn commented 10 years ago

Also, pinging @sebleedelisle :)

If you were waiting on file player pause / resume, there's an initial implementation in the fileplayer-pause-resume branch, though it stumbles on multiple pause / resumes due to the issues I mentioned in the post up there ^

I'm certainly open to someone taking a stab at the last mile here, as it's probably just a one-liner that needs to be taken into account when setting the playhead in play(). It might also have something to do with using kAudioTimeStampSampleTimeValid instead of kAudioTimeStampHostTimeValid like I am now

jasonlevine commented 10 years ago

Hey, I'm in final stretch of SfPC so I doubt I'll have the time to take a stab before December, but keep the updates coming, and I'll dive in when a moment arises.

sebleedelisle commented 10 years ago

Ah cool thanks for letting me know. I'll take a look next time I start to update the audio playback system in PixelPyros. Thanks!