Improve Ambilight Arduino Code

thejman · February 2015

I am currently using the code below to provide my tv with Ambilight on 98 zones. :

I have gotten and edited this code from the ozilight tutorial: http://blog.oscarliang.net/arduino-ambilight-tv-processing-ozilight-2/

Now it is working on my I3 4GB laptop which I use as an HTPC, but it only generating 5 fps. I would like to go to a minimum of at least 15 fps.

I believe this can be made a lot faster, and I am asking you guys for help! :)

The most gain can be gotten in the draw() function so I would like any ideas on the following:

How to implement Threads and where do you think I should do it? I was wondering about creating threads for each side of the screen, one for sending serial data etc.
Is there a faster way to get the pixel data from the screen? is it better to use an external library etc.
Any general improvement points.

All help and ideas are welcome.

Draw()

void draw(){

  //get screenshot into object "screenshot" of class BufferedImage
  BufferedImage screenshot = bot.createScreenCapture(dispBounds);

  // Pass all the ARGB values of every pixel into an array
  int[] screenData = ((DataBufferInt)screenshot.getRaster().getDataBuffer()).getData();

  data_index = 2; // 0, 1 are predefined header

  for(int i=0; i<leds.length; i++) {  // For each LED...

    int r = 0;
    int g = 0;
    int b = 0;

    for(int o=0; o<256; o++)    
    {       //ARGB variable with 32 int bytes where               
        int pixel = screenData[ pixelOffset[i][o] ];            
        r += pixel & 0x00ff0000;            
        g += pixel & 0x0000ff00;            
        b += pixel & 0x000000ff;        
    }           
    // Blend new pixel value with the value from the prior frame   

    ledColor[i][0]  = (short)(((( r >> 24) & 0xff) * (255 - fade) + prevColor[i][0] * fade) >> 8);
    ledColor[i][1]  = (short)(((( g >> 16) & 0xff) * (255 - fade) + prevColor[i][1] * fade) >> 8);
    ledColor[i][2]  = (short)(((( b >>  8) & 0xff) * (255 - fade) + prevColor[i][2] * fade) >> 8);

    serialData[data_index++] = (byte)ledColor[i][0];
    serialData[data_index++] = (byte)ledColor[i][1];
    serialData[data_index++] = (byte)ledColor[i][2];

    float preview_pixel_left  = (float)dispBounds.width  /5 / led_num_x * leds[i][0] ;
    float preview_pixel_top    = (float)dispBounds.height /5 / led_num_y * leds[i][1] ;

    color rgb = color(ledColor[i][0], ledColor[i][1], ledColor[i][2]);
    fill(rgb);  
    rect(preview_pixel_left, preview_pixel_top, preview_pixel_width, preview_pixel_height);

  }

  if(port != null) {

    // wait for Arduino to send data
    for(;;){

      if(port.available() > 0){
        int inByte = port.read();
        if (inByte == 'y')
          break;
      }

    }
    port.write(serialData); // Issue data to Arduino

  }

  // Benchmark, how are we doing?
  println("" + frameRate);
  arraycopy(ledColor, 0, prevColor, 0, ledColor.length);

}

All Code

import java.awt.*;
import java.awt.image.*;
import processing.serial.*;
import java.io.FileWriter;

/*
// using 12 RGB LEDs
static final int led_num_x = 4;
static final int led_num_y = 4;
static final int leds[][] = new int[][] {
  {1,3}, {0,3}, // Bottom edge, left half
  {0,2}, {0,1}, // Left edge
  {0,0}, {1,0}, {2,0}, {3,0}, // Top edge
  {3,1}, {3,2}, // Right edge
  {3,3}, {2,3}, // Bottom edge, right half
};

*/

// using 25 RGB LEDs
static final int led_num_x = 10;
static final int led_num_y = 6;
static final int leds[][] = new int[][] {
  {2,5}, {1,5}, {0,5}, // Bottom edge, left half
  {0,4}, {0,3}, {0,2}, {0,1}, // Left edge
  {0,0}, {1,0}, {2,0}, {3,0}, {4,0}, {5,0}, {6,0}, {7,0}, {8,0}, {9,0}, // Top edge
  {9,1}, {9,2}, {9,3}, {9,4}, // Right edge
  {9,5}, {8,5}, {7,5}, {6,5}  // Bottom edge, right half

};

static final short fade = 70;

static final int minBrightness = 120;

// Preview windows
int window_width;
int window_height;
int preview_pixel_width;
int preview_pixel_height;

int[][] pixelOffset = new int[leds.length][256];

// RGB values for each LED
short[][]  ledColor    = new short[leds.length][3],
      prevColor   = new short[leds.length][3];  

byte[][]  gamma       = new byte[256][3];
byte[]    serialData  = new byte[ leds.length * 3 + 2];
int data_index = 0;

//creates object from java library that lets us take screenshots
Robot bot;

// bounds area for screen capture         
Rectangle dispBounds;

// Monitor Screen information    
GraphicsEnvironment     ge;
GraphicsConfiguration[] gc;
GraphicsDevice[]        gd;

Serial           port;

PrintWriter output;

void createLog()
{
 // Create a new file in the sketch directory
  output = createWriter("log.txt");
  output.flush();  
  output.close();
}

void writeLog(String toWrite)
{   
  File f = new File("log.txt");
  if(!f.exists()){
    println("Creating log");
    createLog();
  }
  try {
    FileWriter output = new FileWriter(sketchPath + "/log.txt", true);
    output.write(toWrite);
    output.write("\r\n");
    output.flush();
    output.close();
  }catch (IOException e){
      e.printStackTrace();
  }


//  output = createWriter("positions.txt");  
//  output.println(toWrite);
//  output.flush();
}

void setup(){

  int[] x = new int[16];
  int[] y = new int[16];

  // ge - Grasphics Environment
  ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
  // gd - Grasphics Device
  gd = ge.getScreenDevices();
  DisplayMode mode = gd[0].getDisplayMode();
  dispBounds = new Rectangle(0, 0, mode.getWidth(), mode.getHeight());
  println("display width: ");
  println(dispBounds.width);

  println("mode width: ");
  println(mode.getWidth());

  println("mode height : ");
  println(mode.getHeight());


  // Preview windows
  window_width      = mode.getWidth()/5;
  window_height      = mode.getHeight()/5;
  preview_pixel_width     = window_width/led_num_x;
  preview_pixel_height   = window_height/led_num_y;

  // Preview window size
  size(window_width, window_height);

  //standard Robot class error check
  try   {
    bot = new Robot(gd[0]);
  }
  catch (AWTException e)  {
    println("Robot class not supported by your system!");
    exit();
  }

  float range, step, start;

  for(int i=0; i<leds.length; i++) { // For each LED...

    // Precompute columns, rows of each sampled point for this LED

    // --- for columns -----
    range = (float)dispBounds.width / led_num_x;
    // we only want 256 samples, and 16*16 = 256
    step  = range / 16.0; 
    start = range * (float)leds[i][0] + step * 0.5;

    for(int col=0; col<16; col++) {
      x[col] = (int)(start + step * (float)col);
    }

    // ----- for rows -----
    range = (float)dispBounds.height / led_num_y;
    step  = range / 16.0;
    start = range * (float)leds[i][1] + step * 0.5;

    for(int row=0; row<16; row++) {
      y[row] = (int)(start + step * (float)row);
    }

    // ---- Store sample locations -----

    // Get offset to each pixel within full screen capture
    for(int row=0; row<16; row++) {
      for(int col=0; col<16; col++) {
        pixelOffset[i][row * 16 + col] = y[row] * dispBounds.width + x[col];
      }
    }

  }

  // Open serial port. this assumes the Arduino is the
  // first/only serial device on the system.  If that's not the case,
  // change "Serial.list()[0]" to the name of the port to be used:
  // you can comment it out if you only want to test it without the Arduino

 //port = new Serial(this, Serial.list()[0], 115200);

  // A special header expected by the Arduino, to identify the beginning of a new bunch data.  
  serialData[0] = 'o';
  serialData[1] = 'z';

  println("Writing pixels offset");
 // WritePixelOffset();  
}

void WritePixelOffset()
{
  writeLog("x length : " + pixelOffset.length + " y length : " + pixelOffset[0].length);

  for(int f = 0; f < pixelOffset.length; f++)
  {
     for(int g = 0; g < pixelOffset[f].length; g ++)
     {
        writeLog("f: " + f + "  g: " + g + " value: " + pixelOffset[f][g]); 
     }
  }
}

void draw(){

  //get screenshot into object "screenshot" of class BufferedImage
  BufferedImage screenshot = bot.createScreenCapture(dispBounds);

  // Pass all the ARGB values of every pixel into an array
  int[] screenData = ((DataBufferInt)screenshot.getRaster().getDataBuffer()).getData();

  data_index = 2; // 0, 1 are predefined header

  for(int i=0; i<leds.length; i++) {  // For each LED...

    int r = 0;
    int g = 0;
    int b = 0;

    for(int o=0; o<256; o++)    
    {       //ARGB variable with 32 int bytes where               
        int pixel = screenData[ pixelOffset[i][o] ];            
        r += pixel & 0x00ff0000;            
        g += pixel & 0x0000ff00;            
        b += pixel & 0x000000ff;        
    }           
    // Blend new pixel value with the value from the prior frame   

    ledColor[i][0]  = (short)(((( r >> 24) & 0xff) * (255 - fade) + prevColor[i][0] * fade) >> 8);
    ledColor[i][1]  = (short)(((( g >> 16) & 0xff) * (255 - fade) + prevColor[i][1] * fade) >> 8);
    ledColor[i][2]  = (short)(((( b >>  8) & 0xff) * (255 - fade) + prevColor[i][2] * fade) >> 8);

    serialData[data_index++] = (byte)ledColor[i][0];
    serialData[data_index++] = (byte)ledColor[i][1];
    serialData[data_index++] = (byte)ledColor[i][2];

    float preview_pixel_left  = (float)dispBounds.width  /5 / led_num_x * leds[i][0] ;
    float preview_pixel_top    = (float)dispBounds.height /5 / led_num_y * leds[i][1] ;

    color rgb = color(ledColor[i][0], ledColor[i][1], ledColor[i][2]);
    fill(rgb);  
    rect(preview_pixel_left, preview_pixel_top, preview_pixel_width, preview_pixel_height);

  }

  if(port != null) {

    // wait for Arduino to send data
    for(;;){

      if(port.available() > 0){
        int inByte = port.read();
        if (inByte == 'y')
          break;
      }

    }
    port.write(serialData); // Issue data to Arduino

  }

  // Benchmark, how are we doing?
  println("" + frameRate);
  arraycopy(ledColor, 0, prevColor, 0, ledColor.length);

}

PhiLho · February 2015

Moved topic to the Arduino section, formated code and list (you need a space after the dash).

See Processing forum rules and advices

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Improve Ambilight Arduino Code

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