Re: [Jack-Devel] JACK connects only JACK apps or any apps?

On Sun, Nov 4, 2012 at 9:28 PM, Cid_Huang[¶ÀÀ·êM] <[hidden]>wrote:

> ** ** ** ** ** ** **
>
> Hi,****
>
> ** **
>
> I need to confirm if JACK connects only JACK apps or any apps. I need to
> play a sound in my app with background music, and that sound will be sent
> only to Skype or any chat apps I choose, but the background music will not
> be sent to Skype or the chat apps I choose. On Windows, there is a
> commercial SDK ¡§Virtual Audio Streaming¡š able to do this through
> establishing a virtual microphone.
>

actually, this does not connect *any* apps. there are many different audio
APIs on Windows, and any given solution for "virtual devices" tends to
support only a subset of them. for example, the one you have found will not
support pro-audio apps that use the ASIO API (unlike JACK on Windows, which
conversely will not support apps that use DirectSound, WinMME and others).


> On Mac, there is a free app called Soundflower seems able to do this.
>

JACK exists on the OS X too. There is also Audio HiJack there. Each of them
uses a different mechanism to provide support for any app on OS X, which is
relatively simple because CoreAudio is the only native audio API there.


> But I have not found any equivalent software on linux. JACK is almost the
> only close lib I could found. So I need to make sure if it can fit my need.
>

JACK *is* the equivalent. However, it was not designed to connect arbitrary
applications, because it was intended for use as part of pro-audio and
music-creation workflows. This puts more requirements on applications that
want to share audio streams via JACK, because they must be capable of
meeting more rigid timing deadlines than those written for other APIs.
However, many people have found ways to interface most other applications
on Linux with JACK. There is no single best way to do this, which is why
the FAQ at jackaudio.org outlines various different methods to use that
depend on the audio API used by a particular application.

Many Linux distributions now use PulseAudio as an intermediate between
(desktop) applications and the audio drivers, and it is possible to
redirect PulseAudio streams to play back via JACK. The JACK FAQ has some
information on this too, although the arch linux wiki that patrick linked
to is also good. Note that almost all "pro-audio" and "music creation"
software on Linux can use JACK natively, and thus these steps are only
required when connecting desktop/consumer/office apps to other things.

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