movie2serial video format problem, I think

edited February 2018 in Raspberry PI

I've used this code for multiple projects at this point without many issues but am now running into an unexpected problem which I am unsure how to solve. I have little to no experience with Processing but was getting some help from people a few months back ago when I started to use this code.

The project is a large LED panel installation on 40 panels, the code will run through processing on a raspberry pi so I am using this pi compatible version someone helped me find. I have one video which almost successfully runs on these 40 panels with a bit of lag (which isn't the worst for the project) but it is not the video I intend to use! In comparing it to the video which I do want to use I am not sure what the difference is. I made the first video which works a few months ago so I can't remember if I did anything different but both videos are made in final cut (mov) and then converted to mp4 online. In final cut I made the dimensions of both videos 640 x 360 and both were H264. The first video moves a bit slower and looks more lo-res but I believe those to be qualities from the original source before I imported and edited in FinalCut.

I believe the problem to be related to the amount/size of data being processed. I should mention that both videos will work according to processing and be recognized by the panels but the issue is that the video I want to use does not play consistently. One teensy may send part of the video to the LEDs mostly correct while another teensy's LEDs start to pick up after 10 seconds and then flickers a spectrum of random colors. None of the teensys seem to be synced up with this second video (though all teensys are mounted on the OctoBoards and connected to each other to sync.)

I'm wondering if anyone has any advice for what to do to the video to make it play correctly.

I have tried using HandBrake to also change some qualities of the video but have no clue what I'm doing really and all of my test have yielded no results.

I also noticed that the flickering happens more when theres a bigger change in color supposed to be happening

I suppose the problem could relate to how many rows I have, not sure, but the other video does seem to be working mostly properly. I am inserting some photos that show the project, some of the panels still need some work so thats why one is pink (wrong RGB ordered lights) and the all white ones just have no data input yet.

Anyone have any ideas?

I hope I entered this code correctly...

    `/*  OctoWS2811 movie2serial.pde - Transmit video data to 1 or more
          Teensy 3.0 boards running OctoWS2811 VideoDisplay.ino
        http://www.pjrc.com/teensy/td_libs_OctoWS2811.html
        Copyright (c) 2013 Paul Stoffregen, PJRC.COM, LLC

        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
        in the Software without restriction, including without limitation the rights
        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        copies of the Software, and to permit persons to whom the Software is
        furnished to do so, subject to the following conditions:

        The above copyright notice and this permission notice shall be included in
        all copies or substantial portions of the Software.

        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
        THE SOFTWARE.
    */

    // To configure this program, edit the following sections:
    //
    //  1: change myMovie to open a video file of your choice    ;-)
    //
    //  2: edit the serialConfigure() lines in setup() for your
    //     serial device names (Mac, Linux) or COM ports (Windows)
    //
    //  3: if your LED strips have unusual color configuration,
    //     edit colorWiring().  Nearly all strips have GRB wiring,
    //     so normally you can leave this as-is.
    //
    //  4: if playing 50 or 60 Hz progressive video (or faster),
    //     edit framerate in movieEvent().

    //import processing.video.*;
    import gohai.glvideo.*;
    import processing.serial.*;
    import java.awt.Rectangle;

    GLMovie myMovie;

    float gamma = 1.7;

    int numPorts=0;  // the number of serial ports in use
    int maxPorts=24; // maximum number of serial ports

    Serial[] ledSerial = new Serial[maxPorts];     // each port's actual Serial port
    Rectangle[] ledArea = new Rectangle[maxPorts]; // the area of the movie each port gets, in % (0-100)
    boolean[] ledLayout = new boolean[maxPorts];   // layout of rows, true = even is left->right
    PImage[] ledImage = new PImage[maxPorts];      // image sent to each port
    int[] gammatable = new int[256];
    int errorCount=0;
    float framerate=0;

    void setup() {
      String[] list = Serial.list();
      delay(20);
      println("Serial Ports List:");
      println(list);
      //serialConfigure("/dev/ttyACM1");  // change these to your port names
      //serialConfigure("/dev/cu.usbmodem3550481");
      serialConfigure("/dev/tty.usbmodem3999691");
      //serialConfigure("/dev/cu.usbmodem3550481");
      //serialConfigure("/dev/ttyACM0");
      serialConfigure("/dev/tty.usbmodem3645941");
      serialConfigure("/dev/tty.usbmodem3694501");
      serialConfigure("/dev/tty.usbmodem3766451");
      if (errorCount > 0) exit();
      for (int i=0; i < 256; i++) {
        gammatable[i] = (int)(pow((float)i / 255.0, gamma) * 255.0 + 0.5);
      }
      size(480, 400, P2D);  // create the window
      String mpath = sketchPath() + "/../../../media/x.mp4";
      println(mpath);
      myMovie = new GLMovie(this, mpath);
      myMovie.loop();  // start the movie :-)
    }


    // movieEvent runs for each new frame of movie data
    void movieEvent(GLMovie m) {
      // read the movie's next frame
      m.read();

      //if (framerate == 0) framerate = m.getSourceFrameRate();
      framerate = 30; // TODO, how to read the frame rate???

      for (int i=0; i < numPorts; i++) {    
        // copy a portion of the movie's image to the LED image
        int xoffset = percentage(m.width, ledArea[i].x);
        int yoffset = percentage(m.height, ledArea[i].y);
        int xwidth =  percentage(m.width, ledArea[i].width);
        int yheight = percentage(m.height, ledArea[i].height);
        ledImage[i].copy(m, xoffset, yoffset, xwidth, yheight,
                         0, 0, ledImage[i].width, ledImage[i].height);
        // convert the LED image to raw data
        byte[] ledData =  new byte[(ledImage[i].width * ledImage[i].height * 3) + 3];
        image2data(ledImage[i], ledData, ledLayout[i]);
        if (i == 0) {
          ledData[0] = '*';  // first Teensy is the frame sync master
          int usec = (int)((1000000.0 / framerate) * 0.75);
          ledData[1] = (byte)(usec);   // request the frame sync pulse
          ledData[2] = (byte)(usec >> 8); // at 75% of the frame time
        } else {
          ledData[0] = '%';  // others sync to the master board
          ledData[1] = 0;
          ledData[2] = 0;
        }
        // send the raw data to the LEDs  :-)
        ledSerial[i].write(ledData); 
      }
    }

    // image2data converts an image to OctoWS2811's raw data format.
    // The number of vertical pixels in the image must be a multiple
    // of 8.  The data array must be the proper size for the image.
    void image2data(PImage image, byte[] data, boolean layout) {
      int offset = 3;
      int x, y, xbegin, xend, xinc, mask;
      int linesPerPin = image.height / 8;
      int pixel[] = new int[8];

      for (y = 0; y < linesPerPin; y++) {
        if ((y & 1) == (layout ? 0 : 1)) {
          // even numbered rows are left to right
          xbegin = 0;
          xend = image.width;
          xinc = 1;
        } else {
          // odd numbered rows are right to left
          xbegin = image.width - 1;
          xend = -1;
          xinc = -1;
        }
        for (x = xbegin; x != xend; x += xinc) {
          for (int i=0; i < 8; i++) {
            // fetch 8 pixels from the image, 1 for each pin
            pixel[i] = image.pixels[x + (y + linesPerPin * i) * image.width];
            pixel[i] = colorWiring(pixel[i]);
          }
          // convert 8 pixels to 24 bytes
          for (mask = 0x800000; mask != 0; mask >>= 1) {
            byte b = 0;
            for (int i=0; i < 8; i++) {
              if ((pixel[i] & mask) != 0) b |= (1 << i);
            }
            data[offset++] = b;
          }
        }
      } 
    }

    // translate the 24 bit color from RGB to the actual
    // order used by the LED wiring.  GRB is the most common.
    int colorWiring(int c) {
      int red = (c & 0xFF0000) >> 16;
      int green = (c & 0x00FF00) >> 8;
      int blue = (c & 0x0000FF);
      red = gammatable[red];
      green = gammatable[green];
      blue = gammatable[blue];
      return (green << 16) | (red << 8) | (blue); // GRB - most common wiring
    }

    // ask a Teensy board for its LED configuration, and set up the info for it.
    void serialConfigure(String portName) {
      if (numPorts >= maxPorts) {
        println("too many serial ports, please increase maxPorts");
        errorCount++;
        return;
      }
      try {
        ledSerial[numPorts] = new Serial(this, portName);
        if (ledSerial[numPorts] == null) throw new NullPointerException();
        ledSerial[numPorts].write('?');
      } catch (Throwable e) {
        println("Serial port " + portName + " does not exist or is non-functional");
        errorCount++;
        return;
      }
      delay(250);
      String line = ledSerial[numPorts].readStringUntil(10);
      if (line == null) {
        println("Serial port " + portName + " is not responding.");
        println("Is it really a Teensy 3.0 running VideoDisplay?");
        errorCount++;
        return;
      }
      String param[] = line.split(",");
      if (param.length != 12) {
        println("Error: port " + portName + " did not respond to LED config query");
        errorCount++;
        return;
      }
      // only store the info and increase numPorts if Teensy responds properly
      ledImage[numPorts] = new PImage(Integer.parseInt(param[0]), Integer.parseInt(param[1]), RGB);
      ledArea[numPorts] = new Rectangle(Integer.parseInt(param[5]), Integer.parseInt(param[6]),
                         Integer.parseInt(param[7]), Integer.parseInt(param[8]));
      ledLayout[numPorts] = (Integer.parseInt(param[5]) == 0);
      numPorts++;
    }

    // draw runs every time the screen is redrawn - show the movie...
    void draw() {
      if (myMovie.available()) {
        movieEvent(myMovie);
      }


      // show the original video
      image(myMovie, 0, 80);

      // then try to show what was most recently sent to the LEDs
      // by displaying all the images for each port.
      for (int i=0; i < numPorts; i++) {
        // compute the intended size of the entire LED array
        int xsize = percentageInverse(ledImage[i].width, ledArea[i].width);
        int ysize = percentageInverse(ledImage[i].height, ledArea[i].height);
        // computer this image's position within it
        int xloc =  percentage(xsize, ledArea[i].x);
        int yloc =  percentage(ysize, ledArea[i].y);
        // show what should appear on the LEDs
        image(ledImage[i], 240 - xsize / 2 + xloc, 10 + yloc);
      } 
    }

    // respond to mouse clicks as pause/play
    boolean isPlaying = true;
    void mousePressed() {
      if (isPlaying) {
        myMovie.pause();
        isPlaying = false;
      } else {
        myMovie.play();
        isPlaying = true;
      }
    }

    // scale a number by a percentage, from 0 to 100
    int percentage(int num, int percent) {
      double mult = percentageFloat(percent);
      double output = num * mult;
      return (int)output;
    }

    // scale a number by the inverse of a percentage, from 0 to 100
    int percentageInverse(int num, int percent) {
      double div = percentageFloat(percent);
      double output = num / div;
      return (int)output;
    }

    // convert an integer from 0 to 100 to a float percentage
    // from 0.0 to 1.0.  Special cases for 1/3, 1/6, 1/7, etc
    // are handled automatically to fix integer rounding.
    double percentageFloat(int percent) {
      if (percent == 33) return 1.0 / 3.0;
      if (percent == 17) return 1.0 / 6.0;
      if (percent == 14) return 1.0 / 7.0;
      if (percent == 13) return 1.0 / 8.0;
      if (percent == 11) return 1.0 / 9.0;
      if (percent ==  9) return 1.0 / 11.0;
      if (percent ==  8) return 1.0 / 12.0;
      return (double)percent / 100.0;
    }`

Screen Shot 2018-02-09 at 10.47.42 PM Screen Shot 2018-02-09 at 10.47.57 PM

Tagged:

Answers

  • edited February 2018

    so like I said, a few of these panels (marked with Xs--ignore them) just aren't wired right yet... and the rest of the panels are somewhat out of order right now. The problem is the video is not being displayed consistently in the panels which are being fed data. The first photo is the problem video version. The second image shows the video x.mp4 playing correctly.

    :(Screen Shot 2018-02-09 at 11.30.31 PM Screen Shot 2018-02-09 at 11.30.47 PM

  • edited February 2018

    The project is a large LED panel installation on 40 panels, the code will run through processing on a raspberry pi

    Anyone have any ideas?

    I have one obvious idea

  • Other than that, the less compressed a video is the faster, generally, it decompresses (and the larger the file, obviously). So try older formats like mpg4 or mpg2. mjpeg, even.

    Doesn't the pi have hardware video decoding for certain formats? Try those. You might need a license.

  • You might even try replacing the percentage and inverse percentage methods with a lookup table the way you do for the gamma.

  • And that problem video looks like an incomplete file, like when I try and watch something before handbrake has finished.

  • Thanks koogs! I tried your recommendations with the mjpeg/ mpg4 /mpg2 and its still about the same... all seem to still have a data date over 100 Mbit/s. I'll try some more throughout the day with handbrake trying to reduce the bitrate/ quality... doesn't seem to change that much so far though.

    I don't think they're incomplete files and they are showing clearly in the processing window but maybe there is something else wrong with them? I really wish I knew more about this stuff.

    Not sure what the percentage/ inverse methods refer to but ill try to look that up as well.

    Anyone else have any other ideas on how to reduce the amount of data / data speed?

    I could also run this from a Mac mini instead of a pi... I just don't want to haha. I've tried it running from both the pi and my laptop at this point and its practically the same problems. maybe the pi even works better, but maybe theres a solution that would work on a Mac that wouldn't work on a pi?

    Really great advice though! Wish it fixed my weird problem.

  • Not sure what the percentage/ inverse methods refer to

    Lines 244, 251, 260

  • edited February 2018

    actually perhaps part of my problem is the Arduino part?

    I've changed the way the teensys feed to panels from the default format... im breaking up the video vertically into 5 strips, placing my x offset 20 percent over each time (I think) ... I assumed this was a percentage, maybe its not?

    I've used this on the teensys:

    /**  OctoWS2811 VideoDisplay.ino - Video on LEDs, from a PC, Mac, Raspberry Pi
        www.pjrc.com/teensy/td_libs_OctoWS2811.html
        Copyright (c) 2013 Paul Stoffregen, PJRC.COM, LLC
    
        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
        in the Software without restriction, including without limitation the rights
        to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
        copies of the Software, and to permit persons to whom the Software is
        furnished to do so, subject to the following conditions:
    
        The above copyright notice and this permission notice shall be included in
        all copies or substantial portions of the Software.
    
        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
        OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
        THE SOFTWARE.
    
    Update: The movie2serial program which transmit data has moved to "extras"
    github.com/PaulStoffregen/OctoWS2811/tree/master/extras
    
      Required Connections
      --------------------
        pin 2:  LED Strip #1    OctoWS2811 drives 8 LED Strips.
        pin 14: LED strip #2    All 8 are the same length.
        pin 7:  LED strip #3
        pin 8:  LED strip #4    A 100 to 220 ohm resistor should used
        pin 6:  LED strip #5    between each Teensy pin and the
        pin 20: LED strip #6    wire to the LED strip, to minimize
        pin 21: LED strip #7    high frequency ringining & noise.
        pin 5:  LED strip #8
        pin 15 & 16 - Connect together, but do not use
        pin 4:  Do not use
        pin 3:  Do not use as PWM.  Normal use is ok.
        pin 12: Frame Sync
    
        When using more than 1 Teensy to display a video image, connect
        the Frame Sync signal between every board.  All boards will
        synchronize their WS2811 update using this signal.
    
        Beware of image distortion from long LED strip lengths.  During
        the WS2811 update, the LEDs update in sequence, not all at the
        same instant!  The first pixel updates after 30 microseconds,
        the second pixel after 60 us, and so on.  A strip of 120 LEDs
        updates in 3.6 ms, which is 10.8% of a 30 Hz video frame time.
        Doubling the strip length to 240 LEDs increases the lag to 21.6%
        of a video frame.  For best results, use shorter length strips.
        Multiple boards linked by the frame sync signal provides superior
        video timing accuracy.
    
        A Multi-TT USB hub should be used if 2 or more Teensy boards
        are connected.  The Multi-TT feature allows proper USB bandwidth
        allocation.  Single-TT hubs, or direct connection to multiple
        ports on the same motherboard, may give poor performance.
    */
    
    #include <OctoWS2811.h>
    
    // The actual arrangement of the LEDs connected to this Teensy 3.0 board.
    // LED_HEIGHT *must* be a multiple of 8.  When 16, 24, 32 are used, each
    // strip spans 2, 3, 4 rows.  LED_LAYOUT indicates the direction the strips
    // are arranged.  If 0, each strip begins on the left for its first row,
    // then goes right to left for its second row, then left to right,
    // zig-zagging for each successive row.
    #define LED_WIDTH      8   // number of LEDs horizontally
    #define LED_HEIGHT     104   // number of LEDs vertically (must be multiple of 8)
    #define LED_LAYOUT     0    // 0 = even rows left->right, 1 = even rows right->left
    
    // The portion of the video image to show on this set of LEDs.  All 4 numbers
    // are percentages, from 0 to 100.  For a large LED installation with many
    // Teensy 3.0 boards driving groups of LEDs, these parameters allow you to
    // program each Teensy to tell the video application which portion of the
    // video it displays.  By reading these numbers, the video application can
    // automatically configure itself, regardless of which serial port COM number
    // or device names are assigned to each Teensy 3.0 by your operating system.
    //#define VIDEO_XOFFSET  0
    //#define VIDEO_YOFFSET  0       // display entire image
    //#define VIDEO_WIDTH    100
    //#define VIDEO_HEIGHT   100
    
    //#define VIDEO_XOFFSET  0
    //#define VIDEO_YOFFSET  0     // display upper half
    //#define VIDEO_WIDTH    100
    //#define VIDEO_HEIGHT   50
    
    //#define VIDEO_XOFFSET  0
    //#define VIDEO_YOFFSET  50    // display lower half
    //#define VIDEO_WIDTH    100
    //#define VIDEO_HEIGHT   50
    
    //#define VIDEO_XOFFSET  0
    //#define VIDEO_YOFFSET  0    // display left half?
    //#define VIDEO_WIDTH    50
    //#define VIDEO_HEIGHT   100
    
    //#define VIDEO_XOFFSET  50
    //#define VIDEO_YOFFSET  0    // display right half?
    //#define VIDEO_WIDTH    50
    //#define VIDEO_HEIGHT   100
    
    #define VIDEO_XOFFSET  60
    #define VIDEO_YOFFSET  0    // display third vertical fifth?
    #define VIDEO_WIDTH    20
    #define VIDEO_HEIGHT   100
    
    const int ledsPerStrip = LED_WIDTH * LED_HEIGHT / 4;
    DMAMEM int displayMemory[ledsPerStrip*6];
    int drawingMemory[ledsPerStrip*6];
    elapsedMicros elapsedUsecSinceLastFrameSync = 0;
    
    const int config = WS2811_800kHz; // color config is on the PC side
    
    OctoWS2811 leds(ledsPerStrip, displayMemory, drawingMemory, config);
    
    void setup() {
      pinMode(12, INPUT_PULLUP); // Frame Sync
      Serial.setTimeout(50);
      leds.begin();
      leds.show();
    }
    
    void loop() {
    //
    // wait for a Start-Of-Message character:
    //
    //   '*' = Frame of image data, with frame sync pulse to be sent
    //         a specified number of microseconds after reception of
    //         the first byte (typically at 75% of the frame time, to
    //         allow other boards to fully receive their data).
    //         Normally '*' is used when the sender controls the pace
    //         of playback by transmitting each frame as it should
    //         appear.
    //   
    //   '$' = Frame of image data, with frame sync pulse to be sent
    //         a specified number of microseconds after the previous
    //         frame sync.  Normally this is used when the sender
    //         transmits each frame as quickly as possible, and we
    //         control the pacing of video playback by updating the
    //         LEDs based on time elapsed from the previous frame.
    //
    //   '%' = Frame of image data, to be displayed with a frame sync
    //         pulse is received from another board.  In a multi-board
    //         system, the sender would normally transmit one '*' or '$'
    //         message and '%' messages to all other boards, so every
    //         Teensy 3.0 updates at the exact same moment.
    //
    //   '@' = Reset the elapsed time, used for '$' messages.  This
    //         should be sent before the first '$' message, so many
    //         frames are not played quickly if time as elapsed since
    //         startup or prior video playing.
    //   
    //   '?' = Query LED and Video parameters.  Teensy 3.0 responds
    //         with a comma delimited list of information.
    //
      int startChar = Serial.read();
    
      if (startChar == '*') {
        // receive a "master" frame - we send the frame sync to other boards
        // the sender is controlling the video pace.  The 16 bit number is
        // how far into this frame to send the sync to other boards.
        unsigned int startAt = micros();
        unsigned int usecUntilFrameSync = 0;
        int count = Serial.readBytes((char *)&usecUntilFrameSync, 2);
        if (count != 2) return;
        count = Serial.readBytes((char *)drawingMemory, sizeof(drawingMemory));
        if (count == sizeof(drawingMemory)) {
          unsigned int endAt = micros();
          unsigned int usToWaitBeforeSyncOutput = 100;
          if (endAt - startAt < usecUntilFrameSync) {
            usToWaitBeforeSyncOutput = usecUntilFrameSync - (endAt - startAt);
          }
          digitalWrite(12, HIGH);
          pinMode(12, OUTPUT);
          delayMicroseconds(usToWaitBeforeSyncOutput);
          digitalWrite(12, LOW);
          // WS2811 update begins immediately after falling edge of frame sync
          digitalWrite(13, HIGH);
          leds.show();
          digitalWrite(13, LOW);
        }
    
      } else if (startChar == '$') {
        // receive a "master" frame - we send the frame sync to other boards
        // we are controlling the video pace.  The 16 bit number is how long
        // after the prior frame sync to wait until showing this frame
        unsigned int usecUntilFrameSync = 0;
        int count = Serial.readBytes((char *)&usecUntilFrameSync, 2);
        if (count != 2) return;
        count = Serial.readBytes((char *)drawingMemory, sizeof(drawingMemory));
        if (count == sizeof(drawingMemory)) {
          digitalWrite(12, HIGH);
          pinMode(12, OUTPUT);
          while (elapsedUsecSinceLastFrameSync < usecUntilFrameSync) /* wait */ ;
          elapsedUsecSinceLastFrameSync -= usecUntilFrameSync;
          digitalWrite(12, LOW);
          // WS2811 update begins immediately after falling edge of frame sync
          digitalWrite(13, HIGH);
          leds.show();
          digitalWrite(13, LOW);
        }
    
      } else if (startChar == '%') {
        // receive a "slave" frame - wait to show it until the frame sync arrives
        pinMode(12, INPUT_PULLUP);
        unsigned int unusedField = 0;
        int count = Serial.readBytes((char *)&unusedField, 2);
        if (count != 2) return;
        count = Serial.readBytes((char *)drawingMemory, sizeof(drawingMemory));
        if (count == sizeof(drawingMemory)) {
          elapsedMillis wait = 0;
          while (digitalRead(12) != HIGH && wait < 30) ; // wait for sync high
          while (digitalRead(12) != LOW && wait < 30) ;  // wait for sync high->low
          // WS2811 update begins immediately after falling edge of frame sync
          if (wait < 30) {
            digitalWrite(13, HIGH);
            leds.show();
            digitalWrite(13, LOW);
          }
        }
    
      } else if (startChar == '@') {
        // reset the elapsed frame time, for startup of '$' message playing
        elapsedUsecSinceLastFrameSync = 0;
    
      } else if (startChar == '?') {
        // when the video application asks, give it all our info
        // for easy and automatic configuration
        Serial.print(LED_WIDTH);
        Serial.write(',');
        Serial.print(LED_HEIGHT);
        Serial.write(',');
        Serial.print(LED_LAYOUT);
        Serial.write(',');
        Serial.print(0);
        Serial.write(',');
        Serial.print(0);
        Serial.write(',');
        Serial.print(VIDEO_XOFFSET);
        Serial.write(',');
        Serial.print(VIDEO_YOFFSET);
        Serial.write(',');
        Serial.print(VIDEO_WIDTH);
        Serial.write(',');
        Serial.print(VIDEO_HEIGHT);
        Serial.write(',');
        Serial.print(0);
        Serial.write(',');
        Serial.print(0);
        Serial.write(',');
        Serial.print(0);
        Serial.println();
    
      } else if (startChar >= 0) {
        // discard unknown characters
      }
    }
    `
    
  • edited February 2018
    #define VIDEO_XOFFSET  60
    #define VIDEO_YOFFSET  0    // display third vertical fifth?
    #define VIDEO_WIDTH    20
    #define VIDEO_HEIGHT   100
    

    this being the edited part that I am using, editing only the offset by 20 for each board

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