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• Extract Wavelength from MP3 as an Image

  13 mai 2016, par Dan

  Are there any good libraries that can help convert an MP3 into an image of its wavelengths (I think that’s the proper term). What I’m looking for is a way to generate the wavelengths of MP3s server-side like is done on Souncloud : http://soundcloud.com/smixx/takin-vc-money-money-cash-ipos

  What would be the best approach to extact that type of image from an audio file ?

• Encode Android's frame's .raw file to .png file format using ffmpeg

  12 avril 2017, par Glex

  I used the script from source. What it does is that it reads the frame-buffer information from the mobile (android) phone and save it as a .raw file. It then uses ffmpeg encoder to create .png file. Unfortunately the png image that I am getting is like (attached below). I tried to play with the "-pix_fmt" option used and tried using rgba instead of rgb32 used in that code (none of them work btw). I used another script (ascreenshooter.py) to analyse the header for this raw image to find few image headers. they are listed as :

  version : 1
  bpp : 32
  size : 2088960
  width : 544
  height : 960
  red_offset : 0
  red_length : 8
  blue_offset : 16
  blue_length : 8
  green_offset : 8
  green_length : 8
  alpha_offset : 0
  alpha_length : 8

  Please suggest if it is possible to encode this .raw image file to png format. If it is possible than what ffmpeg options I should use and if some other more efficient tool does exit for this encoding process.

  Sample raw image as requested :

  http://tabak.csc.ncsu.edu/arpit.raw

  

• Programmatically sending bytes to ffmpeg via STDIN to create still image file

  8 octobre 2019, par Sam Marrocco

  I am attempting to use vb.net code to send individual pixel information as bytes to ffmpeg with the purpose of saving a still DPX image file. I have already successfully read DPX files and output them via STDOUT into vb.net code.

  There seem to be many examples out there of piping movie files but there are also discrepancies, such as some people using image2pipe and others using rawvideo. I am uncertain when to use one over the other. The various methods I’ve tried result in ffmpeg returned errors such as "Packet too small for DPX header" or "Error while decoding stream #0:0 : Invalid data found when processing input". As I understand it, I am not providing a header, only the raw individual pixel RGBRGBRGB.... values as a byte array.

  The arguments sent to ffmpeg via command line are :

  -f image2pipe -pix_fmt rgb24 -s 16x16 -bits_per_raw_sample 8 -c:v dpx -i - \MyPath\MyFilename.dpx

  My vb.net code is as follows :

  Dim P As New Process
  
  P.StartInfo.FileName = m_FFMPEGExecutable_PathFile
  
  P.StartInfo.Arguments = (see above arguments)
  
  P.StartInfo.UseShellExecute = False
  
  P.StartInfo.CreateNoWindow = True
  
  P.StartInfo.RedirectStandardInput = True
  
  p.Start
  
  
  
  
  
  'Test image: A single red, green, blue, black and white pixel followed by all black
  
  
  
  Dim Tiny((16 * 16) - 1) As Byte
  
  
  
  Tiny(0) = 255
  
  Tiny(1) = 0
  
  Tiny(2) = 0
  
  
  
  Tiny(3) = 0
  
  Tiny(4) = 255
  
  Tiny(5) = 0
  
  
  
  Tiny(6) = 0
  
  Tiny(7) = 0
  
  Tiny(8) = 255
  
  
  
  For i As byte = 9 To ((16x16)-1)
  
     Tiny(i) = 255
  
  Next
  
  
  
  'Send the rgb byte array to ffmpeg:
  
  P.StandardInput.BaseStream.Write(Tiny, 0, Tiny.Length)
  
  P.StandardInput.Flush()
  
  P.StandardInput.Close()

  I have tried many variations on the above ffmpeg arguments but cannot seem to avoid these errors. Any suggestions would be appreciated, including information on when to use image2pipe vs. rawvideo.