Re: iPhone OS 3.0 and AudioQueueStart
Re: iPhone OS 3.0 and AudioQueueStart
- Subject: Re: iPhone OS 3.0 and AudioQueueStart
- From: "Jeff Schindler" <email@hidden>
- Date: Thu, 25 Jun 2009 21:01:40 -0400
I seem to remember having similar experiences
with AudioQueueEnqueueBuffersWithParameters on 2.2.
Or perhaps it worked on the first play of a given track
but on subsequent replays the ' future delay' seemed to increase
exponentially
as if there was a bug in the framework that didn't reset the sample time
on AudioQueueStop.
I think FillOutAudioTimeStampWithHostTime
is an inline c++ function that just sets the mHostTime field
of the timestamp struct as well as zeroes out the rest of the struct.
AudioQueueEnqueueBuffersWithParameters only seems to
work on 3.0 with a valid future sample time.
Hence the need to convert host time to sample time.
But isn't host time valid within that structure if set correctly. It seems
to be working to some capacity for me..
perfect sync? hmm i don't know, i don't have any
nice test equipment/harness/objective criteria
to tell me exactly what that means.
my ear says 3.0 is not as good as 2.2
when i try to sync the same
sound files to each other (slight echo
on 3.0 not observable on 2.2).
but it's acceptable for the iphone
and my current goals.
more latency, yes.
harder to code, yes.
but you didn't ask me if it's fun.
I guess I was using the word "perfect" more loosely - we're playing back 8
tracks and we have a test "click" track that we use to test sync - under
2.2, it plays back as a single click when all 8 are played. Under 3.0, they
are all over the place, seemingly random. I'll mess around with it a little
more, but I'm not optimistic. I appreciate your input!
Jeff
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