Re: scheduling question
Re: scheduling question
- Subject: Re: scheduling question
- From: "Stefan Werner" <email@hidden>
- Date: Sun, 18 Jan 2004 20:55:14 +0100
Hi,
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Message: 1
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Date: Thu, 15 Jan 2004 22:19:40 -0800 (PST)
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From: rimas avizienis <email@hidden>
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>
i have written a low latency coreaudio driver which
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sends and receives UDP packets containing audio out
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over the network interface to a special purpose piece
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of hardware i've built. In order to get the
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performance/latency/etc i needed when the machine was
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running under a heavy load (doing real time processing
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of live audio, etc) I had to modify the
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AppleGMACEthernet.kext driver so that the main loop
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in my coreaudio driver (get packet, copy buffers, call
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taketimestamp, send a packet out) gets called at
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primary interrupt time (highest priority in the
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system) by using checkForInterrupt instead of just
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interruptOccurred and having it call my coreaudio
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driver. I basically bypassed the whole networking
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stack.
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>
You might need to do something of that sort...
That woud be more or less be exactly what I need, as I am also working on an
audio over Ethernet application, except that I have a PowerMac on both ends.
While I'd love to stay in userland wherever possible and don't have any
plans to move the receiving side to the kernel, I'd be interested in any
tweaks you did to the audio driver. My current audio driver .kext is using
IOKit timers to replace the hardware interrupt, and I am experiencing
problems when going below 128 frames @ 48kHz. I am in the lucky situation
where bandwidth is not the problem (switched GBit), but if there are ways to
get a lower latency I'd love to hear about them.
-Stefan
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