Sur d’autres sites (8033)

• fftools/ffmpeg : clean up #includes

  25 mars 2023, par Anton Khirnov

  fftools/ffmpeg : clean up #includes
  Drop unneeded ctype.h and math.h.
  
  Group all system headers together.
  
  Sort unconditional includes alphabetically.
  
  Group local includes by the library, sort alphabetically.
  

  • [DH] fftools/ffmpeg.c

• How do i write/replace frames in an existing video ?

  7 novembre 2014, par Ruchir

  I am doing a code on video steganography. I have written the following code :

  def video_write(msg,enc_key) :
  FFMPEG_BIN = "ffmpeg.exe"
  import subprocess as sp
  command = [ FFMPEG_BIN,
  ’-i’, ’vidfl.mp4’,
  ’-f’, ’image2pipe’,
  ’-pix_fmt’, ’rgb24’,
  ’-vcodec’, ’rawvideo’, ’-’]
  pipe = sp.Popen(command, stdout = sp.PIPE,bufsize=10**8)
  import math
  import numpy as np
  # read 1280*720*3 bytes (= 1 frame)
  raw_image = pipe.stdout.read(1280*720*3)
  # transform the byte read into a numpy array
  image = np.fromstring(raw_image, dtype=’uint8’)
  # throw away the data in the pipe’s buffer.
  pipe.stdout.flush()
  image = image.reshape((720,1280,3))
  image1= np.full(1280*720*3,0,int)
  image1 = image1.reshape((720,1280,3))
  for i in range(0,720) :
  for j in range(0,1280) :
  for k in range(0,3) :
  image1[i,j,k]="%08d" % int(bin(image[i,j,k])[2 :])

  Data Hiding

  c=0
  
  for i in msg:
  
      c=c+1
  
  msg_arr=np.full(c,'r',str)
  
  r=0
  
  for i in msg:
  
      msg_arr[r]=i
  
      r=r+1
  
  msg_arrn=np.full(c,0,int)
  
  k=0 
  
  for i in msg_arr:
  
      msg_arrn[k]=ord(i)
  
      k=k+1
  
  msg_len=str(c)
  
  length=0
  
  for i in msg_len:
  
      length=length+1
  
  if length<7:
  
      padtext= 7- length
  
      for i in range(0,padtext):
  
          msg_len='0'+msg_len
  
  msg_head='t'+msg_len
  
  msg_temp_head= msg_head+msg   
  
  l=c+padtext+2
  
  msg_temp_arr=np.full(l,0,int)
  
  for i in range(0,l):
  
      msg_temp_arr[i]=ord(msg_temp_head[i])
  
  msg_enc=np.full(l,0,int)
  
  for i in range(0,l):
  
      msg_enc[i]=int(bin(msg_temp_arr[i]^enc_key)[2:])
  
  rm = 0; gm = 0; bm = 0;
  
  rn = 0; gn = 0; bn = 0;
  
  maxM=720
  
  maxN=1280
  
  z=0
  
  for z in range(0,l):
  
      tempcode= msg_enc[z]
  
      dgts= int(math.log10(tempcode))+1
  
      if dgts<8:
  
          pad= 8- dgts
  
          tempcode= str(tempcode)
  
          for i in range(0,pad):
  
              tempcode='0'+tempcode
  
      a=int(tempcode[0])
  
      if a==0:
  
          image[rm,rn,0]= image[rm,rn,0] & 254
  
      else:
  
          image[rm,rn,0]= image[rm,rn,0]|1
  
      rm= rm+1
  
      if rm>maxM:
  
          rn=rn+1
  
          rm=0
  
      a=int(tempcode[1])
  
      if a==0:
  
          image[gm,gn,1]= image[gm,gn,1]&254
  
      else:
  
          image[gm,gn,1]= image[gm,gn,1]|1
  
      gm=gm+1
  
      if gm>maxM:
  
          gn=gn+1
  
          gm=0
  
      a=int(tempcode[2])
  
      if a==0:
  
          image[bm,bn,2]= image[bm,bn,2]&254
  
      else:
  
          image[bm,bn,2]= image[bm,bn,2]|1
  
      bm=bm+1
  
      if bm>maxM:
  
          bn=bn+1
  
          bm=0
  
      a=int(tempcode[3])
  
      if a==0:
  
          image[bm,bn,2]= image[bm,bn,2]&254
  
      else:
  
          image[bm,bn,2]= image[bm,bn,2]|1
  
      bm=bm+1
  
      if bm>maxM:
  
          bn=bn+1
  
          bm=0
  
      a=int(tempcode[4])
  
      if a==0:
  
          image[gm,gn,1]= image[gm,gn,1]&254
  
      else:
  
          image[gm,gn,1]= image[gm,gn,1]|1
  
      gm=gm+1
  
      if gm>maxM:
  
          gn=gn+1
  
          gm=0
  
      a=int(tempcode[5])
  
      if a==0:
  
          image[rm,rn,0]= image[rm,rn,0] & 254
  
      else:
  
          image[rm,rn,0]= image[rm,rn,0]|1
  
      rm= rm+1
  
      if rm>maxM:
  
          rn=rn+1
  
          rm=0
  
      a=int(tempcode[6])
  
      if a==0:
  
          image[rm,rn,0]= image[rm,rn,0] & 254
  
      else:
  
          image[rm,rn,0]= image[rm,rn,0]|1
  
      rm= rm+1
  
      if rm>maxM:
  
          rn=rn+1
  
          rm=0
  
      a=int(tempcode[7])
  
      if a==0:
  
          image[gm,gn,1]= image[gm,gn,1]&254
  
      else:
  
          image[gm,gn,1]= image[gm,gn,1]|1
  
      gm=gm+1
  
      if gm>maxM:
  
          gn=gn+1
  
          gm=0

  Replace first frame of an existing video ’vidfl_test.mp4’ with frame image.

  command = [ FFMPEG_BIN,
  
              '-y', # (optional) overwrite output file if it exists
  
              '-f', 'rawvideo',
  
              '-vcodec','rawvideo',
  
              '-s', 'hd720', # size of one frame
  
              '-pix_fmt', 'rgb24',
  
              '-r', '15', # frames per second
  
              '-i', '-', # The input comes from a pipe
  
              '-an', # Tells FFMPEG not to expect any audio
  
          '-vcodec', 'mpeg',              
  
              'vidfl_test.mp4' ]
  
  pipe = sp.Popen( command, stdin=sp.PIPE, stderr=sp.PIPE)
  
  pipe.stdin.write(image.tostring())

  This code does not write any frames in the video ’vidfl_test.mp4’. Please help me out with the writing frame in video part of the code.

• avcodec/simple_idct : use predefined M_SQRT2

  14 novembre 2015, par Ganesh Ajjanagadde

  avcodec/simple_idct : use predefined M_SQRT2
  M_SQRT2 is defined in math.h, or in avutil/mathematics.h for
  
  compatibility hacks. This uses this value instead of a floating literal.
  Fixed point values produced by C_FIX(), R_FIX() remain identical.
  Reviewed-by : Michael Niedermayer <michael@niedermayer.cc>
  
  Signed-off-by : Ganesh Ajjanagadde <gajjanagadde@gmail.com>
  

  • [DH] libavcodec/simple_idct.c