Tag: javascript

MBTA API in Max

Sonification of Mass Ave buses, from Nubian to Harvard.

Updated for Max8 and Catalina

This patch requests data from MBTA API 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.

Original project link from 2014: https://reactivemusic.net/?p=17524

MBTA developer website: https://www.mbta.com/developers

This project uses version 3 of the API. There are quality issues with the realtime data. For example, there are bus stops not associated with the route. The direction_id and stop_sequence data from the buses is often wrong. Also, buses that are not in service are not removed from the vehicle list or indicated as such.

The patch uses a [multislider] object to graph the position of the buses along the route – but due to the data problems described above, the positions don’t always reflect the current latitude/longitude coordinates or the bus stop name.

download

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

folder: mbta

patches:

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

You will need  to replace the API key in the message object at the top of the patch with your own key. Or you can probably just remove it. The key distributed with the patch is fake. You can request your own developer API key from MBTA. It’s free.

instructions
  • Open mbta.maxpat
  • Open the Max console window so you can see what’s happening with the data
  • click on the yellow [getstops] message to get the current bus stop data
  • Toggle the metro (at the top of the patch) to start polling
  • Turn on the audio (click speaker icon) 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.

Jitter in javascript

Why would you write Jitter code inside a js object?

  • Math expressions
  • File IO
  • Borrowed code
  • You’re just that way

There are three Jitter javascript tutorials (built in to Max) 45-47

Screen Shot 2015-04-24 at 12.55.44 AM

The Max javascript documentation is generally far flung. A helpful reference by Tim Schenk https://reactivemusic.net/?p=17445

Here’s an example to get started with. It downsamples a movie and changes the background color. Something I often dream about.

Screen Shot 2015-04-24 at 12.35.31 AM

Download

https://github.com/tkzic/max-projects

Folder: jitter-js

  • patch: downsamp-thing.maxpat
  • javascript source: downsamp.js

gibberface web audio

interface.js user interface plus gibberish.js audio engine.

By Charlie Roberts

https://github.com/charlieroberts/gibberface

Audio example of XY controller to contol pitch and pulsewidth of oscillators (pictured above).

Local clone: tkzic/gibberface – WIth a local web server running in tkzic. Here is a typical URL for testing: http://127.0.0.1:8000/gibberface/index.html