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$ gst-launch-1.0 -e v4l2src device=/dev/video0 do-timestamp=true ! 'video/x-raw, width=640, height=480, framerate=30/1' ! tee name=t \
    t. ! queue ! videoconvert ! autovideosink \
    t. ! queue leaky=downstream ! videoconvert ! x264enc tune=zerolatency speed-preset=ultrafast key-int-max=30 byte-stream=true ! splitmuxsink muxer=mp4mux location=output.mp4

Notes:
x264enc appears to be not playing nice with streams. Removing its options blocks the pipeline. Replacing it with vaapih264enc works but then splitmuxsink has to be replaced with filesink for some reason...

vaapih264enc enables hardware acceleration on systems with Intel hardware. The plugin is available if you install an extra package: sudo apt install gstreamer1.0-vaapi 

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System: MacOS Sonoma 14.1.2

First, try to unplug and plug back the Yubikey.

Second, try rebooting the system.

Make sure `opensc` package is up to date. I am using Macports to install utilities/libraries and other command-line utils.
```
$ sudo port upgrade opensc
```

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$ find . -maxdepth 1 -type d \( ! -name . \) -exec bash -c "cd '{}' && git pull" \;

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How to convert private key to WIF

0. Overview

WIF = base58check encode ([version byte][private key][checksum])

version byte = 80 for mainnet, ef for testnet and regtest

checksum = first 4 bytes of double SHA256 of private key

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using Microsoft.ML.Probabilistic.Math;
using Vector = Microsoft.ML.Probabilistic.Math.Vector;

class Program
{
    static void Main(string[] args)
    {
        Vector x = Vector.FromArray(new double[] { 0, 1 });
        //Vector x = new Vector();
        //Vector mean = new Vector(new double[] { 0.1, 1.1 });

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// Two balls in the bag:
// (1) fifty/fifty red (true) or green (false)
// (2) 100% red
//
// Process:
// - pull out the first ball and observe it is red
// - Question: what is the probability the remaining ball is red too?

var model = function() {
  var b1 = flip(0.5)

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import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "HelloServlet", urlPatterns = {"hello"}, loadOnStartup = 1) 
public class HelloServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)

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Note: these instructions are for pre-Sierra MacOS. Sierra and newer users see https://gist.github.com/gravitylow/fb595186ce6068537a6e9da6d8b5b96d by @gravitylow.

If you are getting this in gdb on OSX while trying to run a program:

Unable to find Mach task port for process-id 57573: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))

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using System;
using Microsoft.ML.Probabilistic.Models;

namespace twodice
{
    class Program
    {
        static void Main(string[] args)
        {
            Variable<int> six = Variable.DiscreteUniform(6);

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//
// Zoo: Infer prevalence of 3 animals after a zoo visit
//
// Observed: 3 lions, 2 tigers and 1 bear
//
// Questions:
// - Prevalence of each species
// - Probability of seeing a bear next time
//