Category: DSP

ep-413 DSP – week 11

Filters

fil5

Analog

fil12

Digital

Other

We usually think of filters in terms of frequency. Any process that removes information is a filter. Curation or abstraction, for example.

Reversability

examples

 

MBTA bus data in Max

Sonification of Mass Ave buses, from Harvard to Dudley.

Screen Shot 2014-11-11 at 3.26.16 PM

This patch sends requests to the MBTA developer portal to get the current location of buses – using the Max js object. Latitude and Longitude data is mapped to oscillator pitch. Data is polled every 10 seconds, but it seems like the results might be more interesting to poll at a slower rate, because the updates don’t seem that frequent. And buses tend to stop a lot.

MBTA developer portal: http://reactivemusic.net/?p=17511

Here is the get request URL used in the patch:

http://realtime.mbta.com/developer/api/v2/vehiclesbyroute?api_key=wX9NwuHnZU2ToO7GmGR9uw&route=01&format=json
download

https://github.com/tkzic/internet-sensors

folder: mbta

patches:

  • mbta.maxpat
  • mbta.js
  • poly-oscillator.maxpat
authentication

You will not need authentication to run run this patch. It uses the default developer API-key for testing. Please read the terms of service at the MBTA developer portal. Data should not be polled more often than 10 seconds. You can also request your own developer API key from MBTA.

instructions
  • Open mbta.maxpat
  • Toggle the metro (at the top of the patch) to start polling
  • Turn on the audio (at the bottom of the patch) and turn up the gain

Note: there will be more buses running during rush hours in Boston.  Try experimenting with the polling rate and ramp length in the poly-oscillator patch. Also, you can experiment with the pitch range.

 

data-stream-switch.maxpat

 

ep-413 DSP week 10

Music from data

seagulls

We looked at Vine API Examples from Eli and Steve H.

OSC (Open Sound Control)
  • Max udpsend, udpreceive, touchOsc, aka.speech
  • using a wifi router for performance projects

Using an Osc server to handle Internet API’s

Searchtweet (rate limited): http://reactivemusic.net/?p=17425

Max oggz streaming example: http://reactivemusic.net/?p=17504

We talked about cartoons: http://reactivemusic.net/?p=10091

Sonification
  • parameter mapping
  • modeling
  • earcons

We didn’t talk about alarm fatigue…

MBTA bus example in Max:

(parameter mapping sonification)

http://reactivemusic.net/?p=17524

  • documentation
  • API keys
  • JSON
  • Max example
Unsolved problems

Is it possible to generate music from data?

Audio streaming object in Max

oggrx~ and oggtx~

by Robin Gareus

At Cycling 74 forum: https://cycling74.com/forums/topic/streaming-internet-radio-in-maxmsp/

notes

I was able to receive mp3 files from a server in Max 6.18. using oggrx~. There doesn’t appear to be transport control – so this would need to be built in for synchronization.

Unexpected find: The external uses “secret rabbit code” for resampling. So it works in Max. And we have the source code but not the i386 libs that were used to compile it.

There is no binary for v.7 of oggrx~.mxo, but there is one for v.6

Original c74 post by umma08:

i managed to get Robin Gareus’ externals. They are available here, though they are unmaintained.

The binaries are still online at:

http://gareus.org/d/oggZmax-v0.6-i386.zip

http://gareus.org/d/oggZmax-v0.7-rc2-i386.zip

It’s been more than 3 years (OSX 10.5) since I last looked at it, it
should still work, but I don’t know. Please let me know if you encounter
any problems, so that I can warn others.

I don’t maintain this external anymore. I neither have a MAX/MSP
license, nor do I own any Apple devices. On the upside, complete
source-code is available from

http://gareus.org/gitweb/?p=maxmsp.git;a=snapshot;sf=tgz

ep-413 DSP week 9

Data.

Data

Building a Max patch that displays, transforms, and responds to internet data.

building materials
  • Max (6.1.7 or newer)
  • Soundflower –

Both available from Cycling 74 http://cycling74.com/

The Max patch is based on a tutorial by dude837 called “Automatic Silly Video Generator”

download

The patch at the download link in the video is broken – but the javascript code for the Max js object is intact. You can download the entire patch from the Max-projects archive: https://github.com/tkzic/max-projects folder: maxvine

Internet API’s

API’s (application programming interfaces) provide methods for programs (other than web browsers) to access Internet data. Any app that access data from the web uses an API.

Here is a link to information about the Vine API: https://github.com/starlock/vino/wiki/API-Reference

For example, if you copy this URL into a web browser address bar, it will return a block of data in JSON format about the most popular videos on Vine: https://api.vineapp.com/timelines/popular

HTTP requests

An HTTP request transfers data to or from a server. A web browser handles HTTP requests in the background. You can also write programs that make HTTP requests. A  program called “curl” runs http requests from the terminal command line. Here are examples: http://reactivemusic.net/?p=5916

Response data

Data is usually returned in one of 3 formats:

  • JSON
  • XML
  • HTML

JSON is the preferred method because its easy to access the data structure.

Max HTTP requests

There are several ways to make HTTP requests in Max, but the best method is the js object: Here is the code that runs the GET request for the Vine API:

function get(url)
{
    var ajaxreq = new XMLHttpRequest();
    ajaxreq.open("GET", url);
    ajaxreq.onreadystatechange = readystatechange;
    ajaxreq.send();
}

function readystatechange()
{
    var rawtext = this._getResponseKey("body");
    var body = JSON.parse(rawtext);
    outlet(0, body.data.records[0].videoUrl);
}

 

The function: get() formats and sends an HTTP request using the URL passed in with the get message from Max. When the data is returned to Max, the readystatechange() function parses it and sends the URL of the most popular Vine video out the left outlet of the js object.

Playing Internet audio/video files in Max

The qt.movie object will play videos, with the URL passed in by the read message.

Unfortunately, qt.movie sends its audio to the system, not to Max. You can use Soundflower, or a virtual audio routing app, to get the audio back into Max.

Audio from video

http://reactivemusic.net/?p=12570

Video from audio

http://reactivemusic.net/?p=12570

Other Internet API examples in Max

There is a large archive of examples here: Internet sensors: http://reactivemusic.net/?p=5859

We will look at more of these next week. Here is simple Max patch that uses the Soundcloud API: http://reactivemusic.net/?p=17430

Gokce Kinayoglu has written a java external for Max called Searchtweet: http://cycling74.com/toolbox/searchtweet-design-patches-that-respond-to-twitter-posts/

Many API’s require complex authentication, or money, before they will release their data. We will look ways to access these API’s from Max next week.

Aggregators

There are API services that consolidate many API’s into one API. For example:

Scaling data

Look at the Max tutorial (built in to Max Help) called “Data : data scaling” It contains most of what you need to know to work with streams of data.

Assignment

Using the Vine API patch that we built during the class as a starting point: Build a better app.

Ideas to explore:

  • Is it possible to run several API requests simultaneously?
  • Recording? Time expansion? Effects that evolve over time?
  • Generate music from motion, data, and raw sound?
  • Make a video respond to your instrument or voice?
  • Design a better user interface or external controller?
  • Will this idea work in Max For Live?
  • How would you make adjustments to the loop length, or synchronize a video to other events?
  • Make envelopes to change the dynamic shape?
  • Destruction? Abstraction?
  • Find or write a Max URL streaming object?
  • What about using a different API or other data from the Vine API?

This project will be due in 2-3 weeks. But for next week please bring in your work in progress, and we will help solve problems.