Re: Curious happening with CAPlayThough
Re: Curious happening with CAPlayThough
- Subject: Re: Curious happening with CAPlayThough
- From: Neil Clayton <email@hidden>
- Date: Thu, 8 Jan 2009 15:09:49 +1300
- Comment: DomainKeys? See http://antispam.yahoo.com/domainkeys
Thanks Jeff,
To be more specific, I can click it once and hear this "echo" at the
end of the audio being played. I'm certain it's not because I'm
clicking many times (I'm not clicking wildly, just clicking numerous
times, with delays in between each to hear the outcome).
I'd believe it were something to do with the sound server if I heard
the issue with all three tools that I tried. The fact that it works
with both GarageBand and LineIn makes me suspect something is
different about the code. That's kinda why I asked - not to "blame"
CAPlayThrough in any way but to try to learn what was causing it.
Out of interest, it occurs with afplay as well. Not as obvious, but
it certainly happens.
Here's a recording of the output:
http://dl.getdropbox.com/u/421935/Sample of Audio Blips
On 8/01/2009, at 2:13 PM, Jeff Moore wrote:
I believe that you are probably just hearing the results of either
the System Sound Server handles re-triggering a sound while the
sound is already playing. Or it's just some kind of playback bug in
the SSS (possibly one that's been around for a while but very hard
to reproduce normally).
At any rate, it seems unlikely to be a bug in CAPlayThrough though.
I'd verify this by making sure that just playing audio to this
pipeline with a tool like afplay never has any artifacts.
It is definitely worth writing this up as a bug for us to look at
though.
On Jan 7, 2009, at 4:19 PM, Neil Clayton wrote:
I'm seeing some odd behavior that I'd like to clarify please.
I install Soundflower 2ch, and playthru from that to the built in
line-output. I setup the SF2ch device to be the default output.
I then go to system preferences Sound page, and repeatedly click on
the "Ping" sound (to hear it).
What I hear is that sometimes, it's broken up. As though the last
part of the sample is played again briefly.
Curiously, if I play iTunes to the SF2ch (and through
CAPlaythrough, to the default output) it's absolutely fine.
I'm pretty sure it's not the SF driver itself (but not 100%, I've
not verified the code at all), because it works find if I use
GarageBand for the same task (the playthru part). It also works
fine with LineIn (a similar util, free, from Rogue Amoeba).
So my question is; is this something to do with the way that the AU
is setup? Or to do with flags passed in during the AudioUnitRender?
Or something else entirely?
--
Jeff Moore
Core Audio
Apple
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Neil Clayton
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