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• FFMPEG & OPENGL - RAW Frames

  27 mars 2015, par Marco Reisacher

  I’m building a recorder using a BlackMagic DeckLink Card.
  The program is using OpenGL to display the Frames and FFMPEG (with the glReadPixels() method) to record them.
  I’m setting the viewport in my program to apply a automatic letter-/pillarbox whether the Image/Monitor is 16:9/4:3.
  The problem with that ist that when i capture these frames of this viewport they get of course recorded in the resolution my viewport is (i.e. Full Hd source -> viewport due to monitor with 1600x1200 resolution -> letterbox down to 1600x900) and so FFMPEG records those 1600x1200 with black bars at the top/bottom.

  Is there any possibility to grab the RAW Frame before it gets passed trough the setViewport function and all the rescaling stuff ?

• How to make Fringe Font by using ffmpeg using command line CLI in windows ?

  21 juin 2015, par Ehtesham Shami

  I have a code of ffmpeg of command line. First I have a input image of letter A and then I am using my sample code on that image and getting another output image with different style of letter A.

  I want to make a border on that output letter A.
  I can’t be attached the photos. I have pasted that code sample.

  Please tell me what is the modification is required in that code sample.

  Code Sample :

  ffmpeg -y -i back.jpg -filter_complex "drawtext=fontfile=/Windows/Fonts/meiryo.ttc:text=A:fontcolor=red:x=100:y=100:fontsize=200" output.jpg

• Brute Force Dimensional Analysis

  15 juillet 2010, par Multimedia Mike — Game Hacking, Python

  I was poking at the data files of a really bad (is there any other kind ?) interactive movie video game known simply by one letter : D. The Sega Saturn version of the game is comprised primarily of Sega FILM/CPK files, about which I wrote the book. The second most prolific file type bears the extension ’.dg2’. Cursory examination of sample files revealed an apparently headerless format. Many of the video files are 288x144 in resolution. Multiplying that width by that height and then doubling it (as in, 2 bytes/pixel) yields 82944, which happens to be the size of a number of these DG2 files. Now, if only I had a tool that could take a suspected raw RGB file and convert it to a more standard image format.

  Here’s the FFmpeg conversion recipe I used :

   ffmpeg -f rawvideo -pix_fmt rgb555 -s 288x144 -i raw_file -y output.png
  

  So that covers the files that are suspected to be 288x144 in dimension. But what about other file sizes ? My brute force approach was to try all possible dimensions that would yield a particular file size. The Python code for performing this operation is listed at the end of this post.

  It’s interesting to view the progression as the script compresses to different sizes :

  
  
  

  That ’D’ is supposed to be red. So right away, we see that rgb555(le) is not the correct input format. Annoyingly, FFmpeg cannot handle rgb555be as a raw input format. But this little project worked well enough as a proof of concept.

  If you want to toy around with these files (and I know you do), I have uploaded a selection at : http://multimedia.cx/dg2/.

  Here is my quick Python script for converting one of these files to every acceptable resolution.

  work-out-resolution.py :
  

  PLAIN TEXT

  PYTHON :

  1. # !/usr/bin/python
  2.  
  3. import commands
  4. import math
  5. import os
  6. import sys
  7.  
  8. FFMPEG = "/path/to/ffmpeg"
  9.  
  10. def convert_file(width, height, filename) :
  11.  outfile = "%s-%dx%d.png" % (filename, width, height)
  12.  command = "%s -f rawvideo -pix_fmt rgb555 -s %dx%d -i %s -y %s" % (FFMPEG, width, height, filename, outfile)
  13.  commands.getstatusoutput(command)
  14.  
  15. if len(sys.argv) <2 :
  16.  print "USAGE : work-out-resolution.py <file>"
  17.  sys.exit(1)
  18.  
  19. filename = sys.argv[1]
  20. if not os.path.exists(filename) :
  21.  print filename + " does not exist"
  22.  sys.exit(1)
  23.  
  24. filesize = os.path.getsize(filename) / 2
  25.  
  26. limit = int(math.sqrt(filesize)) + 1
  27. for i in xrange(1, limit) :
  28.  if filesize % i == 0 and filesize & 1 == 0 :
  29.   convert_file(i, filesize / i, filename)
  30.   convert_file(filesize / i, i, filename)