Re: [Jack-Devel] Ethernet-based audio interface using (net)jack idea

I apologise that it's been nearly a year since this thread died. Life
became pretty 'interesting' after my daughter was born!

I was wondering, in the time since the last update happened on this, has
anyone else approached and/or succeeded with a project like this?

On Tue, Sep 6, 2011 at 7:56 AM, Adrian Knoth <[hidden]>wrote:

> On 08/29/11 02:22, Dan Swain wrote:
>
> > This is where I need the advice of those who are experienced with the
> inner
> > workings of netJACK:
>
> Disclaimer: I'm not, but since nobody has answered your question, I took
> a brief look at the code.
>
> > If JACK sends uncompressed audio, is it in a particular format (WAV or
> raw
> > PCM)?
>
> WAV is a file header and obviously not a valid answer. PCM sounds a lot
> better. ;)
>
> If you check netjack_packet.c, there's render_jack_ports_to_payload().
> Depending on the required bitdepth, it either encodes audio data as
> 8bit, 16bit or float. In the float case, those are either native floats
> (depending on the host CPU) or treated as int32 and then converted to
> network byte order.
>
> Given that you're creating a locally attached soundcard, aim for
> float32le. "le" is little endian, most of your target CPUs will use them.
>
> MIDI is encoded as uint32_t in network byte order (see
> encode_midi_buffer).
>
>
> > Assuming that both the master and slave are connected to each other and
> no
> > further identification needs to be made, what data does JACK send along
> with
> > that audio data?
>
> MIDI data and, if run in autoconfig mode, a first packet that configures
> the system. This is probably something neat that you might want to use
> if your box is going to be the jackd master.
>
> > At more of an opinion level, if I were to use this for our 8-channel
> > system, would each channel be dealt with in separate packets (series
> > processing), or should one packet send data from all eight channels
> > (parallel processing)?
>
> That's actually not the question you want to ask. What you want to know
> is how to distribute the samples in the stream. netjack sends a given
> amount (nframes) of the first channel, then followed by the same amount
> of frames for the second channel and so on.
>
> If the payload is too large for a single packet, another one will be
> created.
>
> So there's clearly no "a single packet per channel" concept. Better
> think of a continous bitstream that's split into arbitrary chunks called
> packets.
>
> > Again, if I have missed the scope of anything hear, please let me know,
> and
> > I'll do some more relevant research - this is still very new to me, as
> you
> > can probably tell :-)
>
> How is it going? It seems you're new to C and new to VHDL. Frankly,
> that's not exactly the best starting point for a hardware project. Do
> you have somebody to ask in case of trouble? Like a supervisor?
>
>
>
> Cheers
> 
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>

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