Recherche avancée

Sur d’autres sites (12679)

• Mathematically lossless encoding and decoding of RGB24 image sequence

  25 avril 2013, par curryage

  I am trying to encode a RGB24 image sequence into a mathematically (not merely visually) lossless video. huffyuv was suggested on many online forums so I tried the following.

  ffmpeg -i frames\%06d.png  -vcodec huffyuv test.avi

  The resulting video was then decoded into frames again using ffmpeg

  ffmpeg -i test.avi outframes\%06d.png

  However, the input and output frames are not bit-by-bit identical as promised by huffyuv here. Any idea how I can accomplish this ? My eventual goal is to read the video file using OpenCV but I am willing to cross that bridge later once I obtain a losslessly encoded video file.

  This SO question mentions an attempt to obtain a lossless h264 avi and the summary of responses seems to indicate h264 cannot completely accomplish lossless encoding.

  Once again, to emphasize, I am interested in bit-by-bit identical encoding, not just visually similar. Large file sizes are acceptable as is large compression/decompression time.

• Feeding a series of images to ffmpeg as each image is created [closed]

  5 février 2013, par Mark Schneider

  I'm trying to use ffmpeg to build a 1280x720 slide-show from a sequence of pictures and videos, but I have concerns about potential disk I/O bottleneck.

  I expect a typical slide-show to have about 50 pictures and 2-3 videos (10-15 seconds each at 30 fps). I would like to show each picture for 3-4 seconds (possibly with a
  Ken Burns effect) with a smooth 2 second crossfade between each set of pictures (or for pictures adjacent to videos - between the picture and the first/last frame of the video).

  Given about 50 pictures, the crossfades alone would amount to about 3,000 images (50 transitions x 2 secs/transition x 30 fps). And I suppose if I implement a Ken Burns effect during each picture's 3-4 second showing, I'd have to provide ffmpeg with individual images for each of those frames. (I'm writing a script in Ruby that will pull a list of images from a database and in turn call ImageMagick to create the individual images for each frame. As I understand it, the RMagick library interfaces with ImageMagick such that the output images come back as in-memory objects without needing to write to disk. FWIW, I'm developing in Windows 8 and will deploy to Heroku.)

  All of the slideshow examples I've found online feed ffmpeg a set of images which have already been created. However, in an effort to avoid waiting on considerable disk I/O, I'd like to feed each image to ffmpeg as the image is created rather than create them all in advance.

  Is there a way to send each image file to ffmpeg on the fly as the file is created in memory ?

• JW Player can't play mp4 video downloaded from youtube

  20 janvier 2015, par kheya

  I have doenloaded am mp4 video using IE Realplayer plugin from youtube.
  https://www.youtube.com/watch?v=e3a80c5Ar3Y

  I have a test site on my local machine where I have HTML5 JW Player.

  I download the video and then play locally using realplay to see if it plays.
  I notice that not all mp4 downloads from youtube plays in Realplayer.
  The ones that play in Realplayer also play in JW Player on local website.
  But the mp4 files that don’t play in Realplayer also don’t play in JW player.

  This is the error I get in the player :
  the video playback was aborted due to a corruption problem or because the video used features your browser didnot support mylocalsite/xyz.mp4 undefined

  I tested IE, FF, Chrome. It works nowhere.

  Here is my jw player setup and html :

  <video src="mylocalsite/test.mp4" type="video/mp4" poster="mylocalsite/test.jpg" width="640" height="360"></video>

  player setup :

  var modes = '';
  
  var swfPath = '/content/jw/player.swf';
  
              if (navigator.userAgent.toLowerCase().match(/(android)/) || navigator.userAgent.toLowerCase().match(/(chrom)/)) {                
  
                  modes = [{ type: 'flash', src: swfPath }, { type: "html5"}];
  
              } else {
  
                  modes = [{ type: 'html5' }, { type: 'flash', src: swfPath }, { type: "download"}];
  
              }
  
  
  
  jwplayer('container').setup({                
  
                  'flashplayer': swfPath,                
  
                  'width': '640',
  
                  'height': '360',
  
                  'provider': 'video',
  
                  'modes': modes,                
  
              });

  Here is the details info about the file returned by ffmpeg :

  ffmpeg version 1.1.4 Copyright (c) 2000-2013 the FFmpeg developers
  
    built on Jul 31 2013 02:49:36 with gcc 4.6.2 (GCC)
  
    configuration: --prefix=/c/Users/Administrator/ffmpeg --extra-cflags=-I/c/User
  
  s/Administrator/ffmpeg/include --extra-ldflags=-L/c/Users/Administrator/ffmpeg/l
  
  ib --cpu=i686 --enable-gpl --enable-libfdk-aac --enable-libx264 --enable-nonfree
  
  
  
    libavutil      52. 13.100 / 52. 13.100
  
    libavcodec     54. 86.100 / 54. 86.100
  
    libavformat    54. 59.106 / 54. 59.106
  
    libavdevice    54.  3.102 / 54.  3.102
  
    libavfilter     3. 32.100 /  3. 32.100
  
    libswscale      2.  1.103 /  2.  1.103
  
    libswresample   0. 17.102 /  0. 17.102
  
    libpostproc    52.  2.100 / 52.  2.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\videos\woh.mp4':
  
    Metadata:
  
      major_brand     : dash
  
      minor_version   : 0
  
      compatible_brands: iso6avc1mp41
  
      creation_time   : 2013-09-08 23:34:28
  
    Duration: 00:03:50.96, start: 0.000000, bitrate: 189 kb/s
  
      Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 480x360,
  
  187 kb/s, 25 tbr, 90k tbn, 50 tbc
  
      Metadata:
  
        creation_time   : 2013-09-08 23:34:28
  
        handler_name    : VideoHandler

  What can be causing this issue ?