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Re: How to capture the audio of an output device in OSX
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Re: How to capture the audio of an output device in OSX

  • Subject: Re: How to capture the audio of an output device in OSX
  • From: Dodo <email@hidden>
  • Date: Wed, 10 Sep 2014 06:12:20 +0200

Hi all,


reading the doc of Jack, i find:

"- New Mac Intel use 2 different CoreAudio device for input/output. Jackdmp cannot directly handle 2 devices to do duplex processing. An "aggregate" device has to be built in this case. 
Use the "/Applications/Utilities/Audio MIDI Setup" tool to build and aggregate device that combine both input and output in a single duplex device, then select it when launching jackdmp, with something like :
….
….
jackdmp -R -d coreaudio -n "~:Aggregate:0"

or directly with the JackPilot tool. 
"


So, it seems to me that Jack uses an aggregate device to carry out its task….and I’m not cool with that.

If there is not any other way, I’ll probably try (as already mentioned) to use the “classic” CAPlayThrough source code to forward the input to the output.


As I said, if anybody has any other idea is very very welcome.

Cheers

Dodo




Il giorno 09/set/2014, alle ore 16:26, Paul Davis <email@hidden> ha scritto:



On Tue, Sep 9, 2014 at 10:05 AM, Zack Morris <email@hidden> wrote:

I just want to chime in and say that one of the use cases for this is echo cancellation for VoIP.  I got pretty far with Speex in a shareware game several years back but without having an easy way to capture all of the sound output (including game sounds) there was really no way to adequately cancel the background noise for multiplayer.  I really needed to be able to capture the output of OpenAL as a single stream, run it through Speex’s cancellation, and then send that to the speakers.  I finally got so frustrated that I gave up on it.  One of a dozen reasons why I never finished the game, but it still cost me days of consternation.

P.S. If Apple is concerned about the security implications of applications capturing the output of other applications, then there are other approaches that would work. 

10 years ago, Stephane Letz ported JACK to OS X to provide powerful, arbitrary, free-form routing of audio between any number of applications and devices. The source code is all available, clients are not required to be open source. All streams are precisely sychronized. All CoreAudio applications can interact with JACK without any modifications whatsoever. JACK can also route audio across a network (LAN and WAN), provide shared transport control and more. Stephane has continued to maintain JACK despite several fundamental changes to CoreAudio over the last decade.

Apparently because of some failure at the "marketing level", OS X developers have almost uniformly ignored JACK and continued to live in a little bubble where unless Apple blesses something (like their own distinctly less capable interapplication audio API), it doesn't exist. Or maybe the "marketing" for JACK really did just suck. Who really knows.

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  • Follow-Ups:
    • Re: How to capture the audio of an output device in OSX
      • From: Paul Davis <email@hidden>
    • Re: How to capture the audio of an output device in OSX
      • From: Robert Bielik <email@hidden>
References: 
 >How to capture the audio of an output device in OSX (From: claudio santoro <email@hidden>)
 >Re: How to capture the audio of an output device in OSX (From: Frederic De Jaeger <email@hidden>)
 >Re: How to capture the audio of an output device in OSX (From: Zack Morris <email@hidden>)
 >Re: How to capture the audio of an output device in OSX (From: Paul Davis <email@hidden>)

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