linux-kernel - Re: [very-RFC 0/8] TSN driver for the kernel

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Message-ID: <20160614203810.GC21689@sisyphus.home.austad.us>
Date:	Tue, 14 Jun 2016 22:38:10 +0200
From:	Henrik Austad <henrik@...tad.us>
To:	Richard Cochran <richardcochran@...il.com>
Cc:	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	alsa-devel@...r.kernel.org, netdev@...r.kernel.org,
	Arnd Bergmann <arnd@...aro.org>
Subject: Re: [very-RFC 0/8] TSN driver for the kernel

On Tue, Jun 14, 2016 at 08:26:15PM +0200, Richard Cochran wrote:
> On Tue, Jun 14, 2016 at 11:30:00AM +0200, Henrik Austad wrote:
> > So loop data from kernel -> userspace -> kernelspace and finally back to 
> > userspace and the media application?
> 
> Huh?  I wonder where you got that idea.  Let me show an example of
> what I mean.
> 
> 	void listener()
> 	{
> 		int in = socket();
> 		int out = open("/dev/dsp");
> 		char buf[];
> 
> 		while (1) {
> 			recv(in, buf, packetsize);
> 			write(out, buf + offset, datasize);
> 		}
> 	}
> 
> See?

Where is your media-application in this? You only loop the audio from 
network to the dsp, is the media-application attached to the dsp-device?

Whereas I want to do 

aplay some_song.wav
or mplayer
or spotify
or ..


> > Yes, I know some audio apps "use networking", I can stream netradio, I can 
> > use jack to connect devices using RTP and probably a whole lot of other 
> > applications do similar things. However, AVB is more about using the 
> > network as a virtual sound-card.
> 
> That is news to me.  I don't recall ever having seen AVB described
> like that before.
> 
> > For the media application, it should not 
> > have to care if the device it is using is a soudncard inside the box or a 
> > set of AVB-capable speakers somewhere on the network.
> 
> So you would like a remote listener to appear in the system as a local
> PCM audio sink?  And a remote talker would be like a local media URL?
> Sounds unworkable to me, but even if you were to implement it, the
> logic would surely belong in alsa-lib and not in the kernel.  Behind
> the enulated device, the library would run a loop like the example,
> above.
> 
> In any case, your patches don't implement that sort of thing at all,
> do they?

Subject: [very-RFC 7/8] AVB ALSA - Add ALSA shim for TSN

Did you even bother to look?

-- 
Henrik Austad

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