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Thread: Question about sending pixel data for use with VideoDisplay

  1. #1

    Question about sending pixel data for use with VideoDisplay

    Hello, I have a question about VideoDisplay. I've attached its code below for clarity. I'm working on a program that I want to be able to send graphics to be displayed on an LED panel via an OctoWS2811. My code is able to send the character commands like * and ? as well as the little-endian usec delay value, but I'm not sure how the pixel color values work.

    The length of the array that the color data is read into is equal to ledsPerStrip * 6. Is this because, since the array's type is int, its length is measured in increments of 32 bits? I found that when you multiply the length by 4 (giving its length in bytes) and divide that number by 3 you get the total count of LEDs, which is what I would expect.

    Is it possible for VideoDisplay to be adapted to support the use of RGBW LEDs?

    My program stores its LED color data in the form of a vector of 8-bit integers. If I send this data over the serial connection a byte at a time (rather than 32 bits at a time) is it likely to cause problems?

    Is the number of rows required to be a multiple of 8 because of how the pixel values are converted from the display memory into signals for the LEDs?

    If I have an LED application where the pixels must all be displayed in straight lines rather than zigzagging, is it possible to adapt VideoDisplay for the purpose or should I just zigzag the pixels in the software upstream?

    I've searched but I haven't found answers to these questions on the forum, any help is appreciated.

    Code:
    /*  OctoWS2811 VideoDisplay.ino - Video on LEDs, from a PC, Mac, Raspberry Pi
        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.
    
    Update: The movie2serial program which transmit data has moved to "extras"
    https://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      60   // number of LEDs horizontally
    #define LED_HEIGHT     16   // 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
    
    
    const int ledsPerStrip = LED_WIDTH * LED_HEIGHT / 8;
    
    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
      }
    }
    Last edited by MountainView; 01-03-2022 at 02:31 AM.

  2. #2
    @MountainView: Did anyone ever help you with this, or did you find an answer? I'm sort of stuck on the same problem, oddly enough.
    I'm sure the answer is in here somewhere, but as usual, I'm having a terrible time finding it. I can calculate a white value based on the RGB values I'm getting from movie2serial; I have a function for that, but getting the VideoDisplay_Teensy4.ino sketch to play nice is being a bear.
    Changing "const int config = WS2811_800kHz; // color config is on the PC side" to "const int config = WS2811_GRBW | WS2811_800kHz;" (from the RGBW example) is of limited use; the Teensy will throw its hands up and nothing will happen unless you change the drawingMemory and displayMemory variables from 6 to 8 wide.
    The Processing sketch will run without errors, but the results you'll see on your RGBW tape (SK6812's in my case) will be the same as if you didn't change the "const int =..." line at all, which is to say that the colors are all shifted off incorrectly. At this point, I'd be perfectly happy to write zeros to the W channel...if I could figure out where to do that...
    ...which would seem to be in the Processing sketch, movie2serial...
    I defined the value "white" on line 163 as an integer, setting it to zero, and after commenting out the return line, replaced it with "return (green << 24) | (red << 16) | (blue << 8) | (white);" on line 168.

    You'd think these would work...first, a modified "VideoDisplay.ino"...

    Code:
    /*  OctoWS2811 VideoDisplay.ino - Video on LEDs, from a PC, Mac, Raspberry Pi
        http://www.pjrc.com/teensy/td_libs_OctoWS2811.html
        Copyright (c) 2020 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"
    https://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     176   // 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
    
    
    const int ledsPerStrip = LED_WIDTH * LED_HEIGHT / 8;
    
    DMAMEM int displayMemory[ledsPerStrip*8];
    int drawingMemory[ledsPerStrip*8];
    int incomingMemory[ledsPerStrip*8];
    elapsedMicros elapsedUsecSinceLastFrameSync = 0;
    
    const int config = WS2811_GRBW | 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 *)incomingMemory, sizeof(incomingMemory));
        if (count == sizeof(incomingMemory)) {
          copyIncomingToDrawing();
          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 *)incomingMemory, sizeof(incomingMemory));
        if (count == sizeof(incomingMemory)) {
          copyIncomingToDrawing();
          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 *)incomingMemory, sizeof(incomingMemory));
        if (count == sizeof(incomingMemory)) {
          copyIncomingToDrawing();
          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
      }
    }
    
    
    // The PC transmits data in the transposed format Teensy 3.x uses.
    // This copy function undoes the transpose, so the pixels are
    // put back into the simpler framebuffer format Teensy 4.x uses.
    void copyIncomingToDrawing() {
      const uint32_t width = (LED_WIDTH * LED_HEIGHT / 8) * 4;
      const uint8_t *src = (const uint8_t *)incomingMemory;
      uint8_t *dest = (uint8_t *)drawingMemory;
    
      for (uint32_t x=0; x < width; x++) {
        uint8_t b[8] = {0, 0, 0, 0, 0, 0, 0, 0};
        for (uint8_t mask = 0x80; mask; mask >>= 1) {
          uint8_t bits = *src++;
          if (bits & 0x01) b[0] |= mask;
          if (bits & 0x02) b[1] |= mask;
          if (bits & 0x04) b[2] |= mask;
          if (bits & 0x08) b[3] |= mask;
          if (bits & 0x10) b[4] |= mask;
          if (bits & 0x20) b[5] |= mask;
          if (bits & 0x40) b[6] |= mask;
          if (bits & 0x80) b[7] |= mask;
        }
        dest[width*0] = b[0];
        dest[width*1] = b[1];
        dest[width*2] = b[2];
        dest[width*3] = b[3];
        dest[width*4] = b[4];
        dest[width*5] = b[5];
        dest[width*6] = b[6];
        dest[width*7] = b[7];
        dest = dest + 1;
      }
    }
    and modified "movie2serial.pde" -- with modifications as explained, above.

    Code:
    /*  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) 2018 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.
    */
    
    // Linux systems (including Raspberry Pi) require 49-teensy.rules in
    // /etc/udev/rules.d/, and gstreamer compatible with Processing's
    // video library.
    
    // 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 processing.serial.*;
    import java.awt.Rectangle;
    
    Movie myMovie;
    
    float gamma = 3.0;
    
    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 settings() {
      size(98, 176);  // create the window
    }
    
    void setup() {
      String[] list = Serial.list();
      delay(20);
      println("Serial Ports List:");
      println(list);
      serialConfigure("COM9");  // change these to your port names
      //serialConfigure("/dev/ttyACM1");
      if (errorCount > 0) exit();
      for (int i=0; i < 256; i++) {
        gammatable[i] = (int)(pow((float)i / 255.0, gamma) * 255.0 + 0.5);
      }
      //myMovie = new Movie(this, "/tmp/Toy_Story.avi");
      myMovie = new Movie(this, "final_98x176.mov");
      myMovie.loop();  // start the movie :-)
    }
    
    
    // movieEvent runs for each new frame of movie data
    void movieEvent(Movie m) {
      println("movieEvent");
      // read the movie's next frame
      m.read();
    
      //if (framerate == 0) framerate = m.getSourceFrameRate();
      framerate = 25.0; // 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);
      int white = 0; // could be any value really; use a function to interpolate it from the incoming RGB values...
      red = gammatable[red];
      green = gammatable[green];
      blue = gammatable[blue];
      //return (green << 16) | (red << 8) | (blue); // GRB - most common wiring
      return (green << 24) | (red << 16) | (blue << 8) | (white); // GRBW; we're assuming this is the bit order...
      //return (white << 24) | (green << 16) | (red << 8) | (blue);
    }
    
    // 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(50);
      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() {
      //println("draw");
      // 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;
    }
    Anyone else figured this out?
    Last edited by ariesboy571; 09-25-2022 at 10:27 PM. Reason: including the code

  3. #3
    Hi, haven't gotten to try it yet but will in the near future, although not with RGBW diodes. Thanks for these contributions.

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