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• ffmpeg : How to use blackdetect filter and cut black frames at once

  25 juin 2012, par cache

  I use the following command to detect black screen interval :

  " ffmpeg -i black.mp4 -vf blackdetect=d=1:pic_th=0.70:pix_th=0.10 -an -f null "

  and it gives me output containing this line :
  "[blackdetect @ 0x219a580] black_start:0 black_end:1.44 black_duration:1.44"

  Now I want to cut off black screens in the video from 0-1.44s.

  So my question is : How to use blackdetect filter and cut black frames at once

  Thanks !

• Ffprobe with print json doesn't print anything

  10 septembre 2012, par Richard Knop

  I am trying to get information about a movie (resolution, frame rate, bit rate, codecs, duration etc) in a human readable way. I found this commnad :

  ffprobe -v quiet -print_format json -show_format -show_streams somefile.asf

  In this Stack Overflow question : Get ffmpeg information in friendly way

  But it doesn't work for me. When I try it in a terminal, the output is empty :

  richard@richard-desktop:~/projects/hello-python$ ffprobe -v quiet -print_format json -show_format -show_streams tests/test_1.mpg 
  
  richard@richard-desktop:~/projects/hello-python$ 

• FFMPEG API (compiling with specific formats)

  14 janvier 2012, par JS.

  I am trying to compile FFMPEG to support a single video type (*.mp4).

  I have everything working when I compile for all, but I do not want the extra over-head when I will only use a single format.

  Here's my compile FLAGS now (non-working for MP4). I am sure there are other codecs/decoders I need to specifically enable, but am just having a hard time finding them.

  Compiler directives showing the build flags below :

  FLAGS="$FLAGS --disable-everything"
  
  FLAGS="$FLAGS --enable-encoder=mpeg4video" ## This is the question, what all needs enabling?

  I just do not know video standards well enough to know exactly which codecs / encoders / etc. to turn on.

  av_register_all();
  
  avdevice_register_all();
  
  
  
  byteCtx = av_alloc_put_byte(buffer, BUFFER_SIZE, 0, f, ReadFunc, NULL, SeekFunc);
  
  if (!byteCtx) {
  
      return;
  
  }
  
  // Open video file (here's the failure, doesn't happen when compiled for all)
  
  inputFormat = av_find_input_format("MP4");
  
  if (!inputFormat) {
  
      LOGE(ANDROID_LOG_ERROR, "NDK:", "Null inputformat!");
  
      return;
  
  }