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• Create Video Programmatically with Qt 5.0

  29 mars 2016, par Joey

  We have a QT application that renders programmatically generated QPixmaps one by one to the display and we would like to save this output to a video file. I know that in the past people have recommended using ffmpeg or opencv with Qt to do this. In Qt 5, however, the new QtMultimedia module seems to expose some of this type of functionality. It is now possible, for example, to save video from a camera source in Qt 5 by using the QMediaRecorder as described in http://qt-project.org/doc/qt-5.0/qtmultimedia/qmediarecorder.html#details. With this new functionality, is there any way to use Qt 5 to save our programmatically generated video, or am I still better off using a third party library ?

• Matplotlib animation MovieWriters fails on Ubuntu 12.04

  13 février 2013, par jjwebster

  I am attempting to save matplotlib animations to a movie via ffmpeg on Ubuntu 12.04 LTS (32-bit Desktop). Following the matplotlib example, it fails to load the animation writer : AttributeError: 'module' object has no attribute 'writers' (line 15 of the example) :

  import numpy as np
  
  import matplotlib
  
  matplotlib.use("Agg")
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  def update_line(num, data, line):
  
      line.set_data(data[...,:num])
  
      return line,
  
  
  
  # Set up formatting for the movie files
  
  Writer = animation.writers['ffmpeg']

  Via apt-get, I've tried installing ffmpeg, every codec imaginable, and even tried to compile ffmpeg from source. Nothing works.

  How do I get matplotlib to talk to ffmpeg on Ubuntu ?

• FFMpeg call from Node.js Results in 127

  27 février 2013, par user2009114

  I am having an issue with running an FFMpeg execution command from a Node.js (actually a Meteor) application. From my application I am trying to run :

  /usr/local/bin/ffmpeg-i,/Users//Documents//public/sample_iTunes.mov,-async,1,-acodec,libmp3lame,-b:a,128k,-vf,scale=min(1280\, iw) :-1,-b:v,1000k,-ar,44100,-ac,2,-vcodec,libx264,-x264opts,level=3.0,-profile:v,baseline,-preset:v,superfast,-threads,0,-flags,-global_header,-map,0,-f,segment,-segment_time,10,-segment_list,stream.m3u8,-segment_format,mpegts,-segment_list_flags,live,stream%05d.ts

  However, I get this :
  Transcoder exited with code 127
  chdir() : No such file or directory

  I am using a modified version of hls-vod module (https://github.com/mifi/hls-vod/). I have already tried changing the permissions of ffmpeg via chmod 777, as well as the /cache folder to which it encodes and the public folder containing the sample.mov. None of this seems to work. I installed FFmpeg using Homebrew so the usr/local/bin/ffmpeg is actually a sym link to usr/local/Cellar/..../ffmpeg. I don't know if this would play a part in it. Or perhaps it is something about Meteor.

  Any help would be much appreciated, thanks !