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• Converting RGB images into lossless video with avconv / ffmpeg [migrated]

  19 mai 2013, par despens

  I am trying to convert a series of PNG24 images containing a screen animation to a lossless video, so that every pixel is reproduced exactly as it was in the original. But avconv (and ffmpeg) both produce the same, unsatisfying results, which seem to stem from a colospace conversion going wrong.

  This is the version of avconv I am using :

  avconv version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
  
    built on Apr  2 2013 17:02:36 with gcc 4.6.3

  Each of the images is 1280×800 pixels in size. They do not contain any photographic motives, but specially dithered patterns.

  I used the qtrle codec because apparently this is a lossless codec that works very much like animated GIFs or animated PNGs. However, during the conversion to video there seems to happen a color space conversion ("filter") that is messing with the pixels.

  This is the avconv output :

  $ avconv -f image2 -r 30 -i frames.png/wth-%08d.png -vcodec qtrle -pix_fmt rgb24 -t 15 qtrle-30fps-rgb.mov
  
  avconv version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
  
    built on Apr  2 2013 17:02:36 with gcc 4.6.3
  
  Input #0, image2, from 'frames.png/wth-%08d.png':
  
    Duration: 00:11:17.96, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: png, bgra, 1280x800, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
  File 'qtrle-30fps-rgb.mov' already exists. Overwrite ? [y/N] y
  
  [buffer @ 0x740a00] w:1280 h:800 pixfmt:bgra
  
  [avsink @ 0x742ac0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x743680] w:1280 h:800 fmt:bgra -> w:1280 h:800 fmt:rgb24 flags:0x4
  
  Output #0, mov, to 'qtrle-30fps-rgb.mov':
  
    Metadata:
  
      encoder         : Lavf53.21.1
  
      Stream #0.0: Video: qtrle, rgb24, 1280x800, q=2-31, 200 kb/s, 30 tbn, 30 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (png -> qtrle)
  
  Press ctrl-c to stop encoding
  
  frame=  450 fps= 22 q=0.0 Lsize=  126056kB time=15.00 bitrate=68843.4kbits/s    
  
  video:126052kB audio:0kB global headers:0kB muxing overhead 0.003441%

  This is an original PNG image file :

  

  This is a screenshot of the video being replayed :

  

  Please note that you need to see these images in their original 1280×800 resolution to notice the differences.

  Here is a side-by-side comparison, with the left picture being the original and the right one the outcome after video encoding :

  

  Is there any way I can produce a truly lossless, pixel-perfect video file from a series of PNGs ?

• Creating RTSP stream in Java - not serving a file

  9 mai 2016, par user2959589

  I’ve done quite a bit of searching and have not found any clear answers. I would like to create a RTSP stream in my Java server app. This stream isn’t just sending out an existing file. No, I want it to stream some images generated from within Java. For example, I might generate a spinning cube, or a graph that updates based on some input (number of queries on my server, data from a sensor, etc), or something like that.

  Essentially I’ll be creating a series of BufferedImages (perhaps 10 per second) and I need to stream them out as RTSP with reasonable video compression. As an advanced aspect, I might want to add some sound after I have the basics working, such as "beep" when the graph goes over some value.

  I’ve seen all the various tool options. There are Java bindings for FFMPEG, VLC, and gstreamer, and perhaps others. But I haven’t seen anyone using them to do what I am proposing here.

  One obvious way to do this is to write the BufferedImages to files, then use ffmpeg to turn those into a video format file of some kind, and then serve that file. That would work, but I need something that’s efficient and low latency (near real-time), not writing out files and converting them.

  Any ideas ? Thank you !

• FFMPEG VBS process simultaneous files

  16 septembre 2020, par user726720

  I need to achieve to process multiple video files simultaneously rather then in series. The below code processes files to be one after another. How can I run multiple ffmpeg sessions to convert the files simultaneously

  


  The below code is working fine but processes one file at a time :

  


  For Each oFile In folderFSO.GetFolder("C:\Users\admin\Documents\TestFiles").Files
   If UCase(folderFSO.GetExtensionName(oFile.Name)) = "MXF" Then
     strSplashImagePath = Left(oFile.Name, Len(oFile.Name) - 4) & ".mp4"
     Cmd = "cmd.exe /c ffmpeg.exe -y -i ""C:\Users\admin\Documents\TestFiles\"&oFile.Name&"""  -ab 128k -acodec aac -ac 2 -strict -2 -b:v 12000k -f mp4 -g 34 -pix_fmt yuv420p -r 25 -s 1920x1080 -vcodec h264 -preset ultrafast ""C:\Users\admin\Documents\TestFiles\"&strSplashImagePath&""""
     objShell.Run Cmd, 10, True

   end if


  


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