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• Use ffmpeg to modify single frame without remux ?

  6 février 2017, par 1337GameDev

  I am curious of a fast way to modify a video, slightly, as to force the video to hash differently than the source. I want to avoid changes to meta tags, as these are parsed from the container file and not the video data itself.

  I will be using a process to compare videos for analytical work, but the process requires the 2 inputs to have differing hashes for the video content (otherwise the analytical process yields odd results). I am testing an improvement on this process, and need to have very similar videos.

  I have currently just used a ffmpeg bash script and filtered a VERY light 2x2 pixel for the first second of the video (90% transparent) and this seems to do the trick as they hash differently, but it requires demux / remux of the video, which takes forever if I want to analyze a lot of videos.

  Is there a way, using ffmpeg, to simple modify a single frame (specified by a time value) and change a single pixel and just copy the rest of the video contents ?

• avutil/tests/audio_fifo.c : Memory leak and tab space fixes

  28 décembre 2016, par Thomas Turner

  avutil/tests/audio_fifo.c : Memory leak and tab space fixes
  Prevents memory leak when read_samples_from_audio_fifo() is
  
  called more than once by deallocating before reallocating
  
  more memory.
  Fixes space indentation for contents in ERROR().
  Signed-off-by : Thomas Turner <thomastdt@googlemail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavutil/tests/audio_fifo.c

• java.lang.NoClassDefFoundError : Could not initialize class on Linux (Works fine on Windows)

  26 décembre 2016, par Jake Miller

  I’m using a C++ FFmpeg wrapper for Java (org.bytedeco.javacpp). This works perfectly on a Windows machine (my development machine) but throws this error when ran on Linux (Amazon Web Services Elastic Beanstalk) :

  java.lang.NoClassDefFoundError: Could not initialize class org.bytedeco.javacpp.avutil
  
      at java.lang.Class.forName0(Native Method) ~[na:1.8.0_111]
  
      at java.lang.Class.forName(Class.java:348) ~[na:1.8.0_111]
  
      at org.bytedeco.javacpp.Loader.load(Loader.java:472) ~[javacpp-1.2.1.jar!/:1.2.1]
  
      at org.bytedeco.javacpp.Loader.load(Loader.java:417) ~[javacpp-1.2.1.jar!/:1.2.1]
  
      at org.bytedeco.javacpp.avformat$AVFormatContext.<clinit>(avformat.java:2819) ~[ffmpeg-3.2.1-1.3.jar!/:1.2.1]
  
      at org.bytedeco.javacv.FFmpegFrameGrabber.startUnsafe(FFmpegFrameGrabber.java:391) ~[javacv-1.3.jar!/:1.3]
  
      at org.bytedeco.javacv.FFmpegFrameGrabber.start(FFmpegFrameGrabber.java:385) ~[javacv-1.3.jar!/:1.3]
  
  </clinit>

  I’ve been troubleshooting for the past 2 days and have tried the following to fix the issue :

  • upgrade to Linux to 2.4
  • downgrading javacpp to 1.2.1
  • running mvn clean
  • running mvn -U
  • deleting contents of /.m2/ and redownloading dependencies
  • various combinations of dependency versions
  • git clone on a Linux VM & running mvn install there

  When looking further into the issue, I stumbled upon documentation for avformat$AVFormatContext as it’s in the stack trace posted above (6th line). The documentation for a C++ class named AVFormatContext. Whenever I attempt to view the class in Eclipse, it says Source Not Found.

  My question : could this problem possibly be caused by the C++ libraries on my Linux VM ? None of the above solutions fixed it so this is my only hypothesis as of now.

  Here’s my other Stack Overflow question regarding this subject : Java.lang.NoClassDefFoundError caused by FFmpeg when deployed on Linux as a packaged .war (Works on development machine)