This plugin for Saleae Logic allows you to decode WS5812 LED control signals.

I use an export of this to play back a captured strandtest output in a bl.ocks.org block (since I don't currently have the 60 LEDs it used by default).

CSV export includes both the broken out values and a combined hex color value:

Time [s],LED,R,G,B,RGB
0.023266583333333,0,1,0,108,#01006c
0.023296916666667,1,1,0,96,#010060
0.023326916666667,2,1,0,84,#010054
0.023356916666667,3,1,0,72,#010048
0.023386916666667,4,1,0,57,#010039
0.023417000000000,5,1,0,45,#01002d
0.023447000000000,6,1,0,33,#010021
0.023477000000000,7,1,0,21,#010015

Download the Logic SDK and extract it somewhere on your machine. In my case, it's ~/stuff/SaleaeAnalyzerSdk-1.1.32.

Clone the repo and cd into the top level of it:

git clone https://github.com/dustin/logic-ws2812
cd logic-ws2812

Symlink the include and lib directories into your tree:

ln -s ~/stuff/SaleaeAnalyzerSdk-1.1.32/{include,lib} .

Run the build script:

./build_analyzer.py

In the Developer tab in Logic preferences, specify the path for loading new plugins, then copy the built plugin into that location:

cp release/* /path/specified/in/Logic/preferences