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• What is pkt_size in ffprobe -show_frames ?

  8 juillet 2020, par Null_404

  I am running ffprobe -show_frames and _show_packets on a .ts file and trying to find the size of each I B P frame in the stream. Is this field in the -show_frames option getting what I need ?

  


  And for the size field given by -show_packets, all the packets are very different sizes. I thought the TS packets should all be around 188 bytes, but that doesn't seem to be the case based on the output.

  


  Thanks in advance

  


• 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)

• How to Capture the Desktop and System Sounds using FFMPEG and C ?

  3 décembre 2014, par CaptainObvious

  I’m new to multimedia programming, but have lots of experience in programming in C in general. I want to develop my own program to capture( record ) the desktop and save it to a youtube compatible file using the ffmpeg API. Due to my inexperience in the multimedia field, I don’t know where to start looking in the ffmpeg API for such a function or the terminology commonly used to refer to such functionality. I’ve tried googling to see if I could find any examples or tutorials or how to use ffmpeg to do something similar to this, but I have found nothing except the ways it can be done using the pre-compiled programs on the command line. The only tutorial I have found relating to ffmpeg and C was Dranger’s tutorial, but that only covers how to make a simple video player. Can someone provide an example or direct me to the correct line of API calls in order to implement such a program ?