Simple MJPEG stream decoder for Unity written in C#

MJPEGStreamDecoder.cs

/*
 * I needed a simple MJPEG Stream Decoder and I couldn't find one that worked for me.
 * 
 * It reads a response stream and when there's a new frame it updates the render texture. 
 * That's it. No authenication or options.
 * It's something stupid simple for readimg a video stream from an equally stupid simple Arduino. 
 * 
 * I fixed most of the large memory leaks, but there's at least one small one left.
 */

using System.IO;
using System.Threading;
using System.Collections;
using System.Collections.Generic;
using System.Net;
using UnityEngine;

public class MJPEGStreamDecoder : MonoBehaviour
{
    [SerializeField] bool tryOnStart = false;
    [SerializeField] string defaultStreamURL = "http://127.0.0.1/stream";

    [SerializeField] RenderTexture renderTexture;

    float RETRY_DELAY = 5f;
    int MAX_RETRIES = 3;
    int retryCount = 0;


    byte[] nextFrame = null;

    Thread worker;
    int threadID = 0;

    static System.Random randu; // I use my own System.Random instead of the shared UnityEngine.Random to avoid collisions
    List<BufferedStream> trackedBuffers = new List<BufferedStream>();

    // Start is called before the first frame update
    void Start()
    {
        randu = new System.Random(Random.Range(0, 65536));
        if (tryOnStart)
            StartStream(defaultStreamURL);
    }

    private void Update()
    {
        if (nextFrame != null)
        {
            SendFrame(nextFrame);
            nextFrame = null;
        }
    }

    private void OnDestroy()
    {
        foreach (var b in trackedBuffers)
        {
            if (b != null)
                b.Close();
        }
    }

    public void StartStream(string url)
    {
        retryCount = 0;
        StopAllCoroutines();
        foreach (var b in trackedBuffers)
            b.Close();

        worker = new Thread(() => ReadMJPEGStreamWorker(threadID = randu.Next(65536), url));
        worker.Start();
    }

    void ReadMJPEGStreamWorker(int id, string url)
    {
        var webRequest = WebRequest.Create(url);
        webRequest.Method = "GET";
        List<byte> frameBuffer = new List<byte>();

        int lastByte = 0x00;
        bool addToBuffer = false;

        BufferedStream buffer = null;
        try
        {
            Stream stream = webRequest.GetResponse().GetResponseStream();
            buffer = new BufferedStream(stream);
            trackedBuffers.Add(buffer);
        }
        catch (System.Exception ex)
        {
            Debug.LogError(ex);
        }
        int newByte;
        while (buffer != null)
        {
            if (threadID != id) return; // We are no longer the active thread! stop doing things damnit!
            if (!buffer.CanRead)
            {
                Debug.LogError("Can't read buffer!");
                break;
            }

            newByte = -1;

            try
            {
                newByte = buffer.ReadByte();
            }
            catch
            {
                break; // Something happened to the stream, start a new one
            }

            if (newByte < 0) // end of stream or failure
            {
                continue; // End of data
            }

            if (addToBuffer)
                frameBuffer.Add((byte)newByte);

            if (lastByte == 0xFF) // It's a command!
            {
                if (!addToBuffer) // We're not reading a frame, should we be?
                {
                    if (IsStartOfImage(newByte))
                    {
                        addToBuffer = true;
                        frameBuffer.Add((byte)lastByte);
                        frameBuffer.Add((byte)newByte);
                    }
                }
                else // We're reading a frame, should we stop?
                {
                    if (newByte == 0xD9)
                    {
                        frameBuffer.Add((byte)newByte);
                        addToBuffer = false;
                        nextFrame = frameBuffer.ToArray();
                        frameBuffer.Clear();
                    }
                }
            }

            lastByte = newByte;
        }

        if (retryCount < MAX_RETRIES)
        {
            retryCount++;
            Debug.LogFormat("[{0}] Retrying Connection {1}...", id, retryCount);
            foreach (var b in trackedBuffers)
                b.Dispose();
            trackedBuffers.Clear();
            worker = new Thread(() => ReadMJPEGStreamWorker(threadID = randu.Next(65536), url));
            worker.Start();
        }
    }

    bool IsStartOfImage(int command)
    {
        switch (command)
        {
            case 0x8D:
                Debug.Log("Command SOI");
                return true;
            case 0xC0:
                Debug.Log("Command SOF0");
                return true;
            case 0xC2:
                Debug.Log("Command SOF2");
                return true;
            case 0xC4:
                Debug.Log("Command DHT");
                break;
            case 0xD8:
                //Debug.Log("Command DQT");
                return true;
            case 0xDD:
                Debug.Log("Command DRI");
                break;
            case 0xDA:
                Debug.Log("Command SOS");
                break;
            case 0xFE:
                Debug.Log("Command COM");
                break;
            case 0xD9:
                Debug.Log("Command EOI");
                break;
        }
        return false;
    }

    void SendFrame(byte[] bytes)
    {
        Texture2D texture2D = new Texture2D(2, 2);
        texture2D.LoadImage(bytes);
        //Debug.LogFormat("Loaded {0}b image [{1},{2}]", bytes.Length, texture2D.width, texture2D.height);

        if (texture2D.width == 2)
            return; // Failure!

        Graphics.Blit(texture2D, renderTexture);
        Destroy(texture2D); // LoadImage discards the previous buffer, so there's no point in trying to reuse it
    }
}

Thank you for sharing your implementation of MJPEG stream :D

Hey how i can use it to stream a live stream in unity??
What steps should i take?
Its my first time using unity so I'm lost!
If you can help me I'd appreciate that.