Recherche avancée

Sur d’autres sites (8919)

• Mixing video streams with a fade transition effect myself

  28 mai 2013, par AsTeR

  I would like to make a a software setup that would let the user switch between two webcam feeds (or more but let's consider two). I would like a fade in/out effect while switching. My main problem is that I don't know how to start.

  There seems to be some ffmpeg tool that could do the job (like libavfilter) but I don't get how I could setup it.

  What should I consider to use if I want to access frame image to make the transition myself ? Is there some simpler way ?

  I know that this question looks really poorly written, but I'm as lost as I look.

• How to change metadata with ffmpeg/avconv ?

  14 juillet 2012, par tampis

  I am writing a python script for producing audio and video podcasts. There are a bunch of recorded media files (audio and video) and text files containing the meta information.

  Now I want to program a function which shall add the information from the meta data text files to all media files (the original and the converted ones). Because I have to handle many different file formats (wav, flac, mp3, mp4, ogg, ogv...) it would be great to have a tool which add meta data to arbitrary formats.

  My Question :

  How can I change the metadata of a file with ffmpeg/avconv without changing the audio or video of it and without creating a new file ? Is there another commandline/python tool which would do the job for me ?

  What I tried so far :

  I thought ffmpeg/avconv could be such a tool, because it can handle nearly all media formats. I hoped, that if I set -i input_file and the output_file to the same file, ffmpeg/avconv will be smart enough to leave the file unchanged. Then I could set -metadata key=value and just the metadata will be changed.

  But I noticed, that if I type avconv -i test.mp3 -metadata title='Test title' test.mp3 the audio test.mp3 will be reconverted in another bitrate.

  So I thought to use -c copy to copy all video and audio information. Unfortunately also this does not work :

  :~$ du -h test.wav # test.wav is 303 MB big
  
  303M    test.wav
  
  
  
  :~$ avconv -i test.wav -c copy -metadata title='Test title' test.wav
  
  avconv version 0.8.3-4:0.8.3-0ubuntu0.12.04.1, Copyright (c) 2000-2012 the
  
  Libav    developers
  
  built on Jun 12 2012 16:37:58 with gcc 4.6.3
  
  [wav @ 0x846b260] max_analyze_duration reached
  
  Input #0, wav, from 'test.wav':
  
  Duration: 00:29:58.74, bitrate: 1411 kb/s
  
      Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
  
  File 'test.wav' already exists. Overwrite ? [y/N] y
  
  Output #0, wav, to 'test.wav':
  
  Metadata:
  
      title           : Test title
  
      encoder         : Lavf53.21.0
  
      Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, 1411 kb/s
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (copy)
  
  Press ctrl-c to stop encoding
  
  size=     896kB time=5.20 bitrate=1411.3kbits/s    
  
  video:0kB audio:896kB global headers:0kB muxing overhead 0.005014%
  
  
  
  :~$ du -h test.wav # file size of test.wav changed dramatically
  
  900K    test.wav

  You see, that I cannot use -c copy if input_file and output_file are the same. Of course I could produce a temporarily file :

  :-$ avconv -i test.wav -c copy -metadata title='Test title' test_temp.mp3
  
  :-$ mv test_tmp.mp3 test.mp3

  But this solution would create (temporarily) a new file on the filesystem and is therefore not preferable.

• FFMpeg + Beanstalk : How to pass the processes to it or achieve the same result without using Beanstalk

  6 avril 2017, par Ilia Rostovtsev

  My problem is that FFMpeg and Mencoder are extremely resourceful and running even one process of it makes HTTPd slow down but multiple processes of (FFMPEG /Mencoder) just hang it (HTTPd) completely. I would like my conversions to be processed with Beanstalk, for example.

  My concrete question is : How to transfer my current jobs to Beanstalk ?

  I have a simple PHP code that triggers conversion :

  RunInBackground('convert.php', array($upload, $video_id), $log_path);

  Now what would Beanstalk correct code would look like so these processes would NOT start all at the same time if multiple videos are uploaded ?

  If you believe that for my needs is better to use something else but Beanstalk and you know how to implement it, I would be still happy to see it !

  Thanks in advance,
  Ilia