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• About image opacity

  23 octobre 2013, par Mikko Koppanen — Imagick

  There is a common misconception that Imagick::setImageOpacity() would work to reduce the opacity of the image. However, as the name says the method actually sets the opacity throughout the image and thus affects also transparent areas.

  To demonstrate let’s first look at this image of a red circle on a transparent background :

  

  Now, let’s apply setImageOpacity on the image :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3. $im->setImageOpacity (0.5) ;
  4. $im->writeImage (’red-circle-setopacity.png’) ;
  5.  ?>

  

  As we can see from the resulting image the transparent background is affected as well.

  In order to actually reduce the opacity of the opaque parts Imagick::evaluateImage can be used instead :

  php

  < view plain text >

  1. < ?php
  2. $im = new Imagick (’red-circle.png’) ;
  3.  
  4. /* Divide the alpha channel value by 2 */
  5. $im->evaluateImage(Imagick: :EVALUATE_DIVIDE, 2, Imagick: :CHANNEL_ALPHA) ;
  6. $im->writeImage (’red-circle-divide.png’) ;
  7.  ?>

  And here are the results :

  

  As the background is already fully transparent so the divide operation causes no changes to it.

  Similar example is available in the PHP manual http://php.net/imagick.evaluateimage and I added a note to setImageOpacity page as well (at the time of writing it has not synced to documentation mirrors yet).

• FFMpeg metadata issue

  12 février 2015, par TameHog

  whenever I run ffmpeg -i filename it returns something like this :

   Metadata:
  
  major_brand     : mp42
  
  minor_version   : 0
  
  compatible_brands: isommp42
  
  creation_time   : 2010-07-16 18:33:45
  
  Duration: 00:00:24.00, start: 0.000000, bitrate: 2443 kb/s
  
  Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s
  
  Metadata:
  
    creation_time   : 2010-07-16 18:33:45
  
    handler_name    : Mainconcept MP4 Sound Media Handler
  
  Stream #0:1(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR 4:3], 2311 kb/s, 30 fps, 30 tbr, 30k tbn, 60 tbc
  
  Metadata:
  
    creation_time   : 2010-07-16 18:33:46
  
    handler_name    : Mainconcept MP4 Video Media Handler

  Except when I run it from java using :

  ProcessBuilder pb = new ProcessBuilder(new String[]{"ffmpeg", "-i", "filename"});
  
      pb.redirectErrorStream(true);
  
      try{
  
          Process p = pb.start();
  
  
  
          BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
  
          String bs = "";
  
          while(br.readLine() != null){
  
              bs += br.readLine();
  
              bs += "\n";
  
          }
  
          return bs;
  
      }catch(IOException e){
  
          e.printStackTrace();
  
      }

  it gives me this :

        built on Jun 17 2013 23:20:06 with gcc 4.6 (GCC)
  
    Metadata:
  
      minor_version   : 0
  
      creation_time   : 2010-07-16 18:33:45
  
      Stream #0:0(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s
  
        creation_time   : 2010-07-16 18:33:45
  
      Stream #0:1(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 640x480 [SAR 1:1 DAR     4:3], 2311 kb/s, 30 fps, 30 tbr, 30k tbn, 60 tbc
  
            creation_time   : 2010-07-16 18:33:46
  
      At least one output file must be specified

  How come when I run it from cmd I get way more data ? Can anybody tell me what I am doing wrong ?

• Extract files from mpeg video

  28 octobre 2013, par A Dark Divided Gem

  Videos created with Camtasia can be shared on the web by exporting the project for the TechSmith Smart Player. The video is exported in the "H264 - MPEG-4 AVC (part10) (avc1)" codec and the export also includes other custom XML, JavaScript and SWF files used by the TechSmith Smart Player.

  These custom files are also "burnt" into the video itself. For example the contents of the XML file can be viewed when opening the MP4 video in a text editor. This allows other services to only ask for the MP4 file when uploading Camtasia videos.

  Therefore my question is how do you extract text and binary files from a MP4 video file ? For this project I am limited to Java but I am happy to call an external executable as well.

  I tried the "-dump_attachment" option in FFmpeg but that didn't work and I am out of ideas.

  C :\Users\Desktop>ffmpeg -dump_attachment:t "" -i getting-started-project.mp4
  ffmpeg version N-57448-gc78a416 Copyright (c) 2000-2013 the FFmpeg developers
    built on Oct 26 2013 18:08:54 with gcc 4.8.2 (GCC)
    configuration : —enable-gpl —enable-version3 —disable-w32threads —enable-av
  isynth —enable-bzlib —enable-fontconfig —enable-frei0r —enable-gnutls —enab
  le-iconv —enable-libass —enable-libbluray —enable-libcaca —enable-libfreetyp
  e —enable-libgsm —enable-libilbc —enable-libmodplug —enable-libmp3lame —ena
  ble-libopencore-amrnb —enable-libopencore-amrwb —enable-libopenjpeg —enable-l
  ibopus —enable-librtmp —enable-libschroedinger —enable-libsoxr —enable-libsp
  eex —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvo-aa
  cenc —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwavp
  ack —enable-libx264 —enable-libxavs —enable-libxvid —enable-zlib
    libavutil      52. 47.101 / 52. 47.101
    libavcodec     55. 38.101 / 55. 38.101
    libavformat    55. 19.104 / 55. 19.104
    libavdevice    55.  5.100 / 55.  5.100
    libavfilter     3. 89.100 /  3. 89.100
    libswscale      2.  5.101 /  2.  5.101
    libswresample   0. 17.104 /  0. 17.104
    libpostproc    52.  3.100 / 52.  3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'getting-started-project.mp4' :
    Metadata :
      major_brand : mp42
      minor_version : 0
      compatible_brands : isommp42
      creation_time : 2013-10-24 15:53:19
      artist :
      description :
      title : Untitled
    Duration : 00:05:41.12, start : 0.000000, bitrate : 314 kb/s
      Stream #0:0(eng) : Video : h264 (Baseline) (avc1 / 0x31637661), yuv420p(tv), 6
  40x360 [SAR 1:1 DAR 16:9], 185 kb/s, 30 fps, 30 tbr, 30k tbn, 60 tbc (default)
      Metadata :
        creation_time : 2013-10-24 15:53:19
        handler_name : Mainconcept MP4 Video Media Handler
      Stream #0:1(eng) : Audio : aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 12
  5 kb/s (default)
      Metadata :
        creation_time : 2013-10-24 15:53:19
        handler_name : Mainconcept MP4 Sound Media Handler
   At least one output file must be specified

  Update : It appears the XML is contained within a custom UUID atom and I just need a way of extracting that.

  Thanks