Re: [Jack-Devel] netjack audio routing from smart OSs (IOS and Android)

Hi,

I think we have to distinguish between Jack (as audio router) and 
Netjack (as protocol):
* Porting the Jack server to iOS has been done, but due to iOS changes 
it cannot be used any more.
* But iOS instead now has an API for "Inter-App Audio".
Using the (quite simple) netjack1 protocol "standalone" (e.g. by 
reimplementing it - no licensing problems here) and providing it as 
"Netjack audio source" could work.

I'm not sure about possible clock issues; I think using the iOS device 
as "netjack master" should work.
When the netjack protocol handling is statically embedded to be used 
only in a certain application, this is probably even less of a problem.

Using the device as "netjack slave" (i.e. "jackd -d net") forces the 
masters clock onto the device while e.g. the audio hardware of the iPad 
has it's own idea of timing.

* Wrt. to Android, I don't know much about this MediaRouter class....
Still, implementing the netjack protocol inside a single application is 
possible (and you already mentioned Jack for Android).

The latency stuff becomes really noticeable when you send AND receive 
channels at the same time; lets say you on the netjack slave you just 
connect an input to an output. Then you will have probably a noticeable 
and non-deterministic delay between these stream back on your device 
(the master).

In contrast, Jack for Android aims to guarantee a certain latency -- 
which, in turn, requires low-latency scheduling from the kernel.

   Tobias


On 26/03/15 14:13, Christian Schoenebeck wrote:
> Hi Matt,
>
> as far as I can see it at the moment, the situation is like this:
>
> iOS: Technically not a problem at all, however due to the nature of iOS and
> its prohibition of DLLs, you will have licensing issues. The authors of
> netjack would need to change the license so that someone could use it there as
> part of a static lib linked into an app distributed on the App Store.
>
> Android: the main issue I still see on Android is that the kernel shipped with
> all Android devices is not real-time safe/low latency capable. Which makes it
> IMO useless for audio applications. Maybe Kim could comment whether there any
> kinds of plans to address this on Android in near future.
>
> CU
> Christian
>
> On Thursday 26 March 2015 12:20:22 Matt Flax wrote:
>> Hi everyone,
>>
>> I think it would be handy to have a transparent netjack audio device for
>> IOS and Android.
>> The idea is that it would enable regular apps to stream audio to netjack
>> servers rather then the Andoroid or IOS hardware.
>> What do you think ?
>>
>> I have done some exploring for Android and also (just) asked Kim Jeong
>> Yeon (the porter of Jack to Android) whether he knew anything - waiting
>> for a response.
>>
>> Here is what I have found for Android :
>> There is a MediaRouter class ...
>> http://grepcode.com/file/repo1.maven.org/maven2/org.robolectric/android-all
>> /5.0.0_r2-robolectric-0/android/media/MediaRouter.java?av=h
>>
>>
>>        This flag ROUTE_TYPE_LIVE_AUDIO is relevant for searching the code.
>>
>> I am not sure how to use it or how to interface to it ?
>> It is possible we can do it directly from JAVA or the C++ NDK.
>>
>> Does anyone know or even know anyone who knows ?
>>
>> Similar for IOS ... anyone know or know anyone who knows ?
>>
>> thanks
>> Matt
> 
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