E1.31 Receive Arduino Mega 2560

#include "FastLED.h"

// enter desired universe and subnet  (sACN first universe is 1)
#define DMX_SUBNET 0
#define DMX_UNIVERSE 1
#define E131_BUFFER_MAX 638
#define E131_ADDRESS_OFFSET 126


// buffers for receiving and sending data
unsigned char E131Buffer[E131_BUFFER_MAX]; //buffer to hold incoming packet,

//Pixel Setup
#define NUM_LEDS 50 //total number of pixels
#define DATA_PIN 51 //pin pixels are connected to
CRGB leds[NUM_LEDS]; //pixel array

void setup()
{
Serial.begin(115200); //initialize serial for USB serial monitor
Serial1.begin(115200); //initialize serial input from ESP8266
FastLED.addLeds<WS2811, DATA_PIN, RGB>(leds, NUM_LEDS); //initialize pixels
Serial.println("Setup Complete");
} //end setup

void E131Received(unsigned char* pbuff, int count)
{
  if ( pbuff[113] == DMX_SUBNET )
  {
    if ( pbuff[114] == DMX_UNIVERSE )
    {
      if ( pbuff[E131_ADDRESS_OFFSET-1] == 0 ) //start code must be 0
      {
        leds[0].setRGB(pbuff[127],pbuff[128],pbuff[129]); //set pixel values
        Serial.println(pbuff[126]); //print value of byte 126 which is DMX channel 1
      }
    }
  }
  FastLED.show(); //output to pixels
}



//checks to see if packet is E1.31 data
int checkE131Headers(unsigned char* messagein, int messagelength)
{
   Serial.print("Byte 1:");
   Serial.println(messagein[1],HEX);
   Serial.print("Byte 4:");
   Serial.println(messagein[4],HEX);
   Serial.print("Byte 12:");
   Serial.println(messagein[12],HEX);
  if ( messagein[1] == 0x10 && messagein[4] == 0x41 && messagein[12] == 0x37)
  {
      int ChannelCount = messagein[123] * 256 + messagein[124]; // number of values plus start code
      return ChannelCount -1; //Return how many values are in the packet.
    }
  return 0;
}

void loop()
{
  if (Serial1.available() > 0)
  {
  int packetSize = Serial1.readBytes(E131Buffer,E131_BUFFER_MAX); //read data into buffer and output size. Size should be 638 bytes.
  if(packetSize) //if data has been received
  {
    int TotalChannels = checkE131Headers(E131Buffer, packetSize); //pass data to see if it is E1.31
    if (TotalChannels) //if data comes back as E1.31
   {
            Serial.println("E1.31 Packet Received");
            E131Received(E131Buffer, TotalChannels); //process data function
}
}
}
} //end loop