[PD] direct connection from pd to webrowser, low latency

katja katjavetter at gmail.com
Fri Apr 26 22:08:16 CEST 2013

Hi Onyx,

What is your aim, do you want to entertain your (physically present)
audience via smart phones instead of PA system?

I have a similar quest pending: to send Pd audio from a wearable computer
over wireless to PA system. It's simpler than your purpose (because it does
not involve an internet browser), but still complicated enough. So far I've
learned that UDP is the preferred protocol for real time audio
transmission, because it can go one way without the time-consuming
error-checking and recovery.

Smart phones only do wireless, and wireless suffers a lot from packet loss,
and packet loss must be concealed with clever dsp routines. Besides that,
there is the (in this case relatively minor) issue of clock drift between
two sound card clocks. Even if you send audio between two computers with
[udpsend~] / [udpreceive~] over an ad hoc (point to point) wireless network
you'll notice these issues. Just try it with two laptops and you'll see
what I mean to say (here's how to set up ad hoc wireless network:

Still I think that ad hoc networking would be the way to go for low latency
local wireless connection. It would not work with regular internet browsers
though. A yet to design (Pd or Jack based) app would be required at the
receiving end, which does packet concealment and clock drift compensation.

About clock drift compensation, Miller Puckette had a hint a while ago,
very probably referring to this article:



On Thu, Apr 25, 2013 at 4:14 PM, onyx at onyx-ashanti.com <
onyxashanti at gmail.com> wrote:

> Greetings!  I hope all is well with you.  I wanted to ask if i might gain
> some of your insight on a project i am undertaking.
> I am currently attempting to stream my audio into html5 capable web
> browsers of smartphones.  i have created a local network and installed
> nginx as my webserver.  i and a friend got everything working with the
> oggcast~ and mp3cast~ objects and the icecast 2 server, but the latency was
> horrific-5-15seconds.  I would like to investigate the idea of taking
> advantage of the plugin-less nature of these modern fast browsers and pipe
> the audio directly into it as directly as possible the same way voip works
> but lower bandwidth and only one way.
> I see that udpsend~ can do alot of what i think i want, but i am confused
> as to how i might connect it with the audio socket in the client browser
> (if socket is even the right term).
> Any insight would be greatly appreciated.  and if i get it working, as
> before, i will document the findings in a step by step once it works.
> thank you.
> cheers!
> Onyx
> --
> www.onyx-ashanti.com
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