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• Fetching movies' frames via ffmpeg and feed it to vlfeat's sift

  16 novembre 2012, par Karl

  I am going to develop a program that uses ffmpeg and vlfeat on a linux server.

  My task is simply : get some frames from a movie file and feed these frames to vlfeat's sift.

  I am reading through some documents regarding using ffmpeg in c development, mainly here and here. As stated in the site, "There is not much "web based" official documentation for using these libraries." And some tutorials there might be a little outdated. I also read around that the API might differ from version to version. So I would like to ask for the following :

  1. Is it safe to follow this tutorial for the current implementation ?

     • If so, given the impression from above, what are some of the things that should be change for the current implementation ? (currently I got ffmpeg-git-c995644)
     • If not, what are the functions to acquire the frames of the movie file in any format ?

  2. For vlfeat side, if I am to feed a movie's image frame from ffmpeg, what kind of conversion is required so that vlfeat's sift implementation can "digest" the movie's image frame ?

• How to make java JMF work to make a video using multiple images ?

  31 janvier 2013, par jeet

  I'm trying to use JMF to make a video using multiple jpg images.
  These images are also saved using ImageIO of Java itself.
  Unfortunately, I cannot find a code sample or a working code/class to accomplish make the video using JMF.

  There was a JpegImagesToMovie.java class here :
  http://www.oracle.com/technetwork/java/javase/documentation/jpegimagestomovie-176885.html
  but that link seems broken.

  Can someone please post a working code, or tell me some other way of making videos with java and a different class ?

  I think a working code on this page might help others like me in future.

  BTW, I also tried to use ffmpeg to compile the video, but that says similar to :

  image2 codec not found 

  When we use java ImageIO to make jpg images, are they not compatible with ffmpeg codecs ?

  java command :

  ImageIO.write(capture, "jpg", new File( uploadPath, filename));

  This is the ffmpeg error :

  ffmpeg.exe -f image2 -i pic\s%d.jpeg -vcodec mpeg2video vid\video.mpg
  
  FFmpeg version SVN-r7760, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  
    configuration:  --enable-memalign-hack --enable-gpl --cpu=i686 --enable-swscaler --enable-pthreads --enable-avisynth --enable-mp3lame --enable-xvid --enable-x264 --enable-libnut --enable-libogg --enable-vorbis --enable-libtheora --enable-faad --enable-faac --enable-libgsm --enable-dts --enable-a52 --enable-amr_nb --enable-amr_wb 
  
    libavutil version: 49.2.0
  
    libavcodec version: 51.29.0
  
    libavformat version: 51.8.0
  
    built on Jan 29 2007 19:58:47, gcc: 3.4.6
  
  [image2 @ 00931554]Could not find codec parameters (Video: mjpeg)
  
  pic\sd.jpeg: could not find codec parameters

• How to create an H264 video for specific Libav decoding

  16 octobre 2013, par James491

  I'm creating a program that decodes and displays videos using Libav. I have complete control over the videos the program uses because I make them beforehand. I am able to seek and decode the videos as needed but only after adjusting to a few quirks of x264 encoded videos. For instance, I have to add 8-10 extra frames at the end of my videos to be able to decode and seek to the original last frame. Is it possible to further customize the encoding of an H264 video using ffmpeg or another application, or perhaps some parameters I can initialize in AVFormatContext or AVCodecContext, in order to solve something like decoding the last frames ? Also, are there any specifics I can add to the video file or implement in decoding to decrease seek time, since all seek commands and positions are predetermined ? My current seeking function is just composed of an avformat_seek_file(...) followed by avcodec_flush_buffers(...). I am already seeking to key frames. I am willing to read and learn if all you have is a recommended page or article to investigate.