Re: MatrixMixer CPU usage
Re: MatrixMixer CPU usage
- Subject: Re: MatrixMixer CPU usage
- From: Jean-Daniel Dupas <email@hidden>
- Date: Mon, 21 Feb 2011 23:28:03 +0100
Le 21 févr. 2011 à 23:08, Kevin Boyce a écrit :
>
> On Feb 21, 2011, at 4:37 PM, Martin Hairer wrote:
>
>>> It seems like MatrixMixer takes a huge amount of CPU, even just sitting there.
>>
>>
>> Sounds like a lot. In Amadeus Pro, I use a MatrixMixer for playback, even if
>> there's only one track present. On my MPB (2.53GHz Core Duo), playback
>> uses about 10% of (one) CPU, but this includes Apple's equalizing / compressing
>> which, as tahome says, already makes up quite a bit of an overhead... Maybe your
>> IO buffers are too small? Mine are currently set to 512 samples. If I go down to
>> 32 samples, my CPU usage for simple playback goes up to 30%, which is closer
>> to what you see... Regards,
>
> Hi Martin,
>
> Thanks, I'll check that.
>
> ***time passes***
>
> Okay, I checked and I'm using the default HAL Output Unit buffer size, which reports as 512 samples.
>
> I'm getting about 18-19% usage of one CPU on my white MB (2.1GHz Core 2 Duo), through the headphone jack. (Same using an iMic.) That's fine performance, but I'm targeting the low end (schools, community theatres, etc.), and many of them still have PPC machines. I don't actually need the MatrixMixer yet, so I could ditch it, but it seems like I must be coming at it all crabbed to be getting that much CPU usage. And it's almost all overhead; it hardly changes when I'm playing a mess of files through it.
>
> Thanks!
When running the Apple Sample code in Instrument, it reveal that almost 100% of the processing is done in -[NSWindow displayIfNeeded] which means that all the overhead you see is due to UI refresh.
Even when running the mixer, the time passed in the audio unit is negligible compare to the UI overhead.
-- Jean-Daniel
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