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• How to Extract motion vectors using FFMPEG on HADOOP from a mp4 video

  27 novembre 2016, par MEHDI SAOUDI

  I want to manipulate videos stored in HDFS with the FFMPEG libraries and store the text file results on HDFS or on Hbase.

  to clarify : I want to extract the motion vectors from a mp4 video with FFMPEG, I can do this locally but I want to do this on my hadoop cluster. locally The command is :

  ffmpeg -flags2 +export_mvs -i input.mp4 -vf codecview=mv=pf+bf+bb output.mp4

  And then I modify the vf_codecview.c file to have the motion vector on a text file. For the moment my goal is to turn the command on hadoop on one video and then on my database of videos.

  thanks for your help

• Unable to open symbol file. Error (20) : Not a directory

  29 octobre 2015, par grzebyk

  I am using ffmpeg library on android to stream live video feed. I have complied ffmpeg for android following roman10 instructions. The application is working correctly - it connects to the server, download the feed, transcode it, rescale it and displays on the device’s screen. However after a certain random moment the app crashes with Fatal signal 11 (SIGSEGV), code 1. I have used ndk-stack to find the source of the problem. Here is the crash dump :

  ********** Crash dump: **********
  
  Build fingerprint: 'google/hammerhead/hammerhead:5.0.1/LRX22C/1602158:user/release-keys'
  
  pid: 25241, tid: 25317, name: AsyncTask #5  >>> com.grzebyk.streamapp <<<
  
  signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x98e74c9c
  
  Stack frame #00 pc 00047924  /data/app/com.grzebyk.streamapp-1/lib/arm/libswscale-3.so: Unable to open symbol file /Users/grzebyk/Documents/New_Eclipse_Projects/StreamApp/libs/armeabi/libStreamApp.so/libswscale-3.so. Error (20): Not a directory
  
  Stack frame #01 pc 00034be8  /data/app/com.grzebyk.streamapp-1/lib/arm/libswscale-3.so (sws_scale+2648): Unable to open symbol file /Users/grzebyk/Documents/New_Eclipse_Projects/StreamApp/libs/armeabi/libStreamApp.so/libswscale-3.so. Error (20): Not a directory

  My native code is located in the StreamApp.cpp file. For me it looks like the app is trying to access libswscale-3.so (part of the ffmpeg) located inside the libStreamApp.so. This seems weird for me…

  All the ffmpeg’s .so files are located in /libs/armeabi/lib*.so. Naturally this includes the "missing" libswscale-3.so. The most disturbing thing is a fact that the app is working perfectly, but it crashes suddenly and it does not need any specific trigger to do so.

  What can I do to either put libswscale-3.so inside labStreamApp.so or to avoid referencing one .so file from another ?

• ffmpeg crop detect python using subprocess

  12 mai 2015, par JRM

  I want to use python subprocess to call ffmpeg and use crop detect to find all black in a video. The crop detect return I want to put into a string variable and put in a database. At the moment I can get the process running in terminal and but I am unsure about how to grab the specific part of the terminal (stdout) output :

  the script :

  def cropDetect():
  
      p = subprocess.Popen(["ffmpeg", "-i", "/Desktop/ffprobe_instance/Crop_detect/video_file.mpg", "-vf", "cropdetect=24:16:0", "-vframes", "10", "dummy.mp4"], stdout=subprocess.PIPE)
  
      result = p.communicate()[0]
  
      print result
  
  
  
  
  
  # SCRIPT
  
  cropDetect()

  Result in terminal :
  [Parsed_cropdetect_0 @ 0x7fa1d840cb80] x1:719 x2:0 y1:575 y2:0 w :-704 h :-560 x:714 y:570 pos:432142 pts:44102 t:0.490022 crop=-704 :-560:714:570

  How do I take "crop=-704 :-560:714:570" and put it into a variable that I can store in a database ?

  As per update :

  def cropDetect1():
  
      p = subprocess.check_output(["ffmpeg", "-i", "/Desktop/ffprobe_instance/Crop_detect/video_file.mpg", "-vf", "cropdetect=24:16:0", "-vframes", "10", "dummy.mp4"])
  
      match = re.search("crop\S+", p)
  
      crop_result = None
  
      if match is not None:
  
          crop_result = match.group()
  
          print "hello %s" % crop_result

  I can’t seem to print out the "crop_result" - I am presuming that means that the variable is empty ?

  UPDATE : Found it :

  def detectCropFile(localPath):
  
      fpath = "/xxx/xx/Desktop/Crop_detect/videos/USUV.mp4"
  
      print "File to detect crop: %s " % fpath
  
      p = subprocess.Popen(["ffmpeg", "-i", fpath, "-vf", "cropdetect=24:16:0", "-vframes", "500", "-f", "rawvideo", "-y", "/dev/null"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
  
      infos = p.stderr.read()
  
      print infos
  
      allCrops = re.findall(CROP_DETECT_LINE + ".*", infos)
  
      print allCrops 
  
      mostCommonCrop = Counter(allCrops).most_common(1)
  
      print "most common crop: %s" % mostCommonCrop
  
      print mostCommonCrop[0][0]
  
      global crop
  
      crop = mostCommonCrop[0][0]
  
      video_rename()

  Use : p = subprocess.Popen(["ffmpeg", "-i", fpath, "-vf", "cropdetect=24:16:0", "-vframes", "500", "-f", "rawvideo", "-y", "/dev/null"], stdout=subprocess.PIPE, stderr=subprocess.PIPE) to pipe it out