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• Dreamcast Development Desktop

  28 mars 2011, par Multimedia Mike — Sega Dreamcast

  Some people are curious about what kind of equipment is required to program a Sega Dreamcast. This is my setup :

  
  
  

  It’s a bit overcomplicated. The only piece in that picture which doesn’t play a role in the Dreamcast development process is the scanner. The Eee PC does the heavy lifting of development (i.e., text editing and cross compilation) and uploads to the Dreamcast via a special serial cable. Those are the most essential parts and are really the only pieces necessary for a lot of algorithmic stuff (things that can be validated via a serial console). But then I have to go up a level where I output video. That’s where things get messy.

  
  
  

  The Mac Mini and giant monitor really just act as a glorified TV in this case. Ideally, it will be more than that. The DC outputs audio and video via composite cables to a Canopus DV capture bridge. That’s connected via FireWire to the external hard drive underneath the Mac Mini, which is connected to the Mac. Adobe Premiere Pro handles the DV capture / display.

  One day I hope to have something worthwhile to capture.

• How to update a byte array in a method, without running it again ?

  18 février 2016, par AR792

  I have a class(an AsyncTask) which does image processing and generates yuv bytes continously, at around 200ms interval.

  Now I send these yuv bytes to another method where the they are recorded using FFmpeg frame recorder :

  public void recordYuvData() {
  
  
  
          byte[] yuv = getNV21();
  
          System.out.println(yuv.length + "  returned yuv bytes  ");
  
          if (audioRecord == null || audioRecord.getRecordingState() != AudioRecord.RECORDSTATE_RECORDING) {
  
              startTime = System.currentTimeMillis();
  
              return;
  
          }
  
          if (RECORD_LENGTH > 0) {
  
              int i = imagesIndex++ % images.length;
  
              yuvimage = images[i];
  
              timestamps[i] = 1000 * (System.currentTimeMillis() - startTime);
  
          }
  
          /* get video data */
  
          if (yuvimage != null && recording) {
  
              ((ByteBuffer) yuvimage.image[0].position(0)).put(yuv);
  
  
  
              if (RECORD_LENGTH <= 0) {
  
                  try {
  
                      long t = 1000 * (System.currentTimeMillis() - startTime);
  
                      if (t > recorder.getTimestamp()) {
  
                          recorder.setTimestamp(t);
  
                      }
  
                      recorder.record(yuvimage);
  
                  } catch (FFmpegFrameRecorder.Exception e) {
  
  
  
                      e.printStackTrace();
  
                  }
  
              }
  
          }
  
      }

  This method ; recordYuvData() is initiated on button click.

  1. If I initiate it only once , then only the initial image gets recorded, rest are not.

  2. If I initiate this each time after the end of the image processing it records but leads to ’weird’ fps count of the video ; and finally this leads to application crash after sometime.

     For above what I feel is, at the end of image processing a new instance of recordYuvData() is created without ending the previous one, accumulating many instances of recordYuvData(). [correct me if I am wrong]

  So, how do I update ’ONLY’ yuv bytes in the method without running it again ?

  Thanks....!

  Edit :

  On Click :

      record.setOnClickListener(new View.OnClickListener() {
  
          @Override
  
          public void onClick(View v) {
  
              recordYuvdata();
  
              startRecording();

  getNV21()

  byte[] getNV21(Bitmap bitmap) {
  
  
  
      int inputWidth = 1024;
  
      int inputHeight = 640;
  
      int[] argb = new int[inputWidth * inputHeight];
  
  
  
      bitmap.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);
  
      System.out.println(argb.length + "@getpixels ");
  
  
  
  
  
      byte[] yuv = new byte[inputWidth * inputHeight * 3 / 2];
  
      encodeYUV420SP(yuv, argb, inputWidth, inputHeight);
  
  
  
      return yuv;
  
  
  
  }
  
  
  
  void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {
  
      final int frameSize = width * height;
  
  
  
      int yIndex = 0;
  
      int uvIndex = frameSize;
  
      System.out.println(yuv420sp.length + " @encoding " + frameSize);
  
  
  
      int a, R, G, B, Y, U, V;
  
      int index = 0;
  
      for (int j = 0; j < height; j++) {
  
          for (int i = 0; i < width; i++) {
  
  
  
              a = (argb[index] & 0xff000000) >> 24; // a is not used obviously
  
              R = (argb[index] & 0xff0000) >> 16;
  
              G = (argb[index] & 0xff00) >> 8;
  
              B = (argb[index] & 0xff) >> 0;
  
  
  
              // well known RGB to YUV algorithm
  
  
  
              Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
  
              U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
  
              V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;
  
  
  
              // NV21 has a plane of Y and interleaved planes of VU each sampled by a factor of 2
  
              //    meaning for every 4 Y pixels there are 1 V and 1 U.  Note the sampling is every other
  
              //    pixel AND every other scanline.
  
              yuv420sp[yIndex++] = (byte) ((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));
  
              if (j % 2 == 0 && index % 2 == 0) {
  
                  yuv420sp[uvIndex++] = (byte) ((V < 0) ? 0 : ((V > 255) ? 255 : V));
  
                  yuv420sp[uvIndex++] = (byte) ((U < 0) ? 0 : ((U > 255) ? 255 : U));
  
              }
  
  
  
              index++;
  
          }
  
      }
  
  }

• Scale image with ffmpeg in bash script

  17 juin 2014, par Brian Bennett

  I’m playing with jclem’s Gifify bash script as a quick way to make GIFs for documentation. It runs on ffmpeg and ImageMagick and I’m trying to find a way to add a variable to scale the produced GIF so I don’t have to go back and add it again. I thought I added the d (resize) variable correctly, but the script fails and just prints the help contents. It does not show my added variable in that help readout. Any ideas ?

  Update

  I solved the problem with printing help contents rather than running the script, but now I’m receiving an error about the -scale parameter.

  convert: invalid argument for option `-scale': -vf @ error/convert.c/ConvertImageCommand/2513.

  Is this because of my if statement syntax for the scale parameter below ?

  #!/bin/bash
  
  
  
  function printHelpAndExit {
  
    echo 'Usage:'
  
    echo '  gifify -conx filename'
  
    echo ''
  
    echo 'Options: (all optional)'
  
    echo '  c CROP:   The x and y crops, from the top left of the image, i.e. 640:480'
  
    echo '  o OUTPUT: The basename of the file to be output (default "output")'
  
    echo '  n:        Do not upload the resulting image to CloudApp'
  
    echo '  r FPS:    Output at this (frame)rate (default 10)'
  
    echo '  s SPEED:  Output using this speed modifier (default 1)'
  
    echo '            NOTE: GIFs max out at 100fps depending on platform. For consistency,'
  
    echo '            ensure that FPSxSPEED is not > ~60!'
  
    echo '  x:        Remove the original file and resulting .gif once the script is complete'
  
    echo '  d SCALE:  Scales GIF image to specified dimensions (default no scale)'
  
    echo ''
  
    echo 'Example:'
  
    echo '  gifify -c 240:80 -o my-gif -x my-movie.mov'
  
    exit $1
  
  }
  
  
  
  noupload=0
  
  fps=10
  
  speed=1
  
  
  
  OPTERR=0
  
  
  
  while getopts "c:o:r:s:d:nx" opt; do
  
    case $opt in
  
      c) crop=$OPTARG;;
  
      h) printHelpAndExit 0;;
  
      o) output=$OPTARG;;
  
      n) noupload=1;;
  
      r) fps=$OPTARG;;
  
      s) speed=$OPTARG;;
  
      x) cleanup=1;;
  
      d) scale=$OPTARG;;
  
      *) printHelpAndExit 1;;
  
    esac
  
  done
  
  
  
  shift $(( OPTIND - 1 ))
  
  
  
  filename=$1
  
  
  
  if [ -z ${output} ]; then
  
    output=$filename
  
  fi
  
  
  
  if [ -z $filename ]; then printHelpAndExit 1; fi
  
  
  
  if [ $crop ]; then
  
    crop="-vf crop=${crop}:0:0"
  
  else
  
    crop=
  
  fi
  
  
  
  if [ $scale ]; then
  
    scale="-vf scale=${scale}:0:0"
  
  else
  
    scale=
  
  fi
  
  
  
  # -delay uses time per tick (a tick defaults to 1/100 of a second)
  
  # so 60fps == -delay 1.666666 which is rounded to 2 because convert
  
  # apparently stores this as an integer. To animate faster than 60fps,
  
  # you must drop frames, meaning you must specify a lower -r. This is
  
  # due to the GIF format as well as GIF renderers that cap frame delays
  
  # < 3 to 3 or sometimes 10. Source:
  
  # http://humpy77.deviantart.com/journal/Frame-Delay-Times-for-Animated-GIFs-214150546
  
  echo 'Exporting movie...'
  
  delay=$(bc -l <<< "100/$fps/$speed")
  
  temp=$(mktemp /tmp/tempfile.XXXXXXXXX)
  
  
  
  ffmpeg -loglevel panic -i $filename $crop -r $fps -f image2pipe -vcodec ppm - >> $temp
  
  
  
  echo 'Making gif...'
  
  cat $temp | convert +dither -layers Optimize -delay $delay -scale $scale - ${output}.gif
  
  
  
  if [ $noupload -ne 1 ]; then
  
    open -a Cloud ${output}.gif
  
  
  
    echo `pbpaste`
  
  
  
    if [ $cleanup ]; then
  
      rm $filename
  
      rm ${output}.gif
  
    fi
  
  else
  
    echo ${output}.gif
  
  fi