Re: Creating Aggregate Devices programmatically
Re: Creating Aggregate Devices programmatically
- Subject: Re: Creating Aggregate Devices programmatically
- From: "B.J. Buchalter" <email@hidden>
- Date: Mon, 01 Aug 2005 16:28:04 -0400
on 8/1/05 3:06 PM, Jeff Moore at email@hidden wrote:
>> Another (and perhaps most important) problem I have encountered is
>> that when
>> I play a QuickTime movie (with two tracks, in this case) through the
>> (working, public) aggregate device, there is a 1 to 2 sec delay
>> before the
>> movie starts playing, during which time nothing happens.
>> Prerolling the
>> movie removes this delay, but still takes 1 - 2 sec to do the
>> prerolling.
>> (This is on a Dual 2Ghz G5, 3.5Gb memory, OS 10.4.2).
>> Unfortunately, this
>> makes responsive starting of movies very tricky when responding to
>> user
>> interaction for triggering playback. Is this just the nature of
>> aggregate
>> devices, or is there anything I can do to reduce this time?
>
> This is expected and can't be avoided. Due to their nature, aggregate
> devices need to ensure that the clocks on the sub-devices have
> settled out and are reasonably accurate. This takes a few time stamps
> from each sub-device, which can be a second or two depending on the
> devices in use. There is nothing you can do to change this.
Couldn't he start the aggregate device after he creates it and simply keep
it running so that it is always "pre-warmed" by the time QT starts running?
The synchronization only happens when the aggregate is started; if it is
already running when QT start talking to it it should be instantaneous (just
like playing after QT has started device during the pre-roll). The device
start would be asynchronous and ostensibly could take place during the rest
of the start up of the app so by the time the user clicked play on
something, everything would be synched and happy...
BR,
B.J. Buchalter
Metric Halo
5 Donovan Drive
Hopewell Junction, NY 12533 USA
tel +1 845 223-6112
fax +1 603 250-2451
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