Searching for a microcontroller with more memory....

I have 900 ws2812b LEDS on a strip. I want to use an arduino as music controller just like here:

This is the code btw:

I read here that the attiny85 has only 512 bytes of memory and thats the reason I can only control up to 100 leds with it (most common arduino microcontrollers have 2kb which is only sufficient for 400 leds).

My question to you: Which board can I use to reproduce the stuff on the youtube video? I already found out that the Atmega1284p has 16kb ram, i could use it. But it seems to me that there is no board commercially available. Is there a (cheap) solution?

There are 1284p boards available. Look harder. I know crossroads sells several designs, and I've seen designs on tindie and ebay.

They're available in a dip package too, so you can make a board on perfboard

Is it possible to use this arduino compatible board?

It's arm and has 64 Kbytes of Flash memory. Is it possible to solder a 3.5 mm audio jack to it? Still searching for a cheap solution.

I think I found the solution:

For less money: Teensy

The ESP8266 should be perfect for this application. This video by CNLohr shows how you can control hundreds of WS2812's using the I2S interface.

An Arduino library for controlling all the WS2812's using I2S can be found here

The ESP8266 should be perfect for this application.

And, if you do not need the RF WiFi section, it can easily be disabled and reduce the ESP8266 current requirements.