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Re: bandwidth limits
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Re: bandwidth limits


  • Subject: Re: bandwidth limits
  • From: Austin Shoemaker <email@hidden>
  • Date: Tue, 23 Sep 2003 20:16:29 -0700

Bill,

I have a few questions that I hope will guide my implementation in the right direction:

1. Is AAC the best choice for optimal decode to a CoreAudio device with 48 outputs, or is there a better choice if disk space is unlimited?

2. How much QuickTime vs. CoreAudio should I use? I imagine I need QuickTime to decode AAC files, but should I use QuickTime from end-to-end or should I get the decompressed buffer from QuickTime and route it through CoreAudio? If I need to do the latter, how do I get a buffer from QuickTime instead of just having it play through?

Thanks a lot,
Austin

On Sep 23, 2003, at 3:15 PM, Bill Stewart wrote:

Roman, et al,

On Tuesday, September 23, 2003, at 09:12 AM, Roman Thilenius wrote:
you will not use any compression for realtime streaming of audio or video,
that would need a bit too much CPU.

Not at all sure what you mean here.

QT's Broadcaster is able to broadcast using AAC (and other audio codecs), speech based codecs like CELP, etc, also do not consume that much CPU either and all of these are entirely usable in a real-time situation. (For instance, AAC on an 800MHz iMac is somewhere in the vicinity of 10% or "real" time for encoding. Decoding AAC on a similar machine is now around 1-2% CPU usage).

You should do some research on the time these processes take as they are in *very* common use (in fact far more use than doing NO compression because the data rates are typically far more crucial and limiting a factor than the CPU needed to compress the data within real-time constraints) - this applies to video even more so than for audio

Bill

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References: 
 >Re: bandwidth limits (From: Bill Stewart <email@hidden>)

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