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• FFMPEG xstack not recognizing inputs

  12 août 2020, par Josh

  I'm trying to arrange three input videos into a single output video using ffmpeg's xstack. I currently have the operations working with a vstack followed by an hstack, but would like to combine them into an xstack for performance.

  


  I've tried copying the syntax from multiple locations such as :

  


  https://trac.ffmpeg.org/wiki/Create%20a%20mosaic%20out%20of%20several%20input%20videos%20using%20xstack

  


  Vertically or horizontally stack (mosaic) several videos using ffmpeg ?

  


  My command is as follows :

  


  


  C :\ffmpeg\bin\ffmpeg.exe -i states_full.mp4 -i title.mp4 -i graphs.mp4" -filter_complex "[0:v] setpts=PTS-STARTPTS, scale=qvga [a0] ; [1:v] setpts=PTS-STARTPTS, scale=qvga [a1] ; [2:v] setpts=PTS-STARTPTS, scale=qvga [a2] ; [a0][a1][a2]xstack=inputs=3:layout=0_0|w0_0|w0_h0[out] " -map "[out]" -c:v libx264 -t '30' -f matroska output.mp4

  


  


  The command always errors out at the same spot, with the same error message :

  


  


  'w0_0' is not recognized as an internal or external command,
operable program or batch file.

  


  


  Some odd behavior is that even when I change the layout section to :

  


  layout=w0_0|0_0|w0_h0


  


  The error message is still on the middle '0_0' meaning it may be an error in formatting.

  


  This issue is very strange, as the vstack and hstack still work, only the xstack fails.

  


• Ffmpeg : Encoding images with audio [duplicate]

  10 février 2015, par Dries

  This question is an exact duplicate of :

  • Ffmpeg : writing audio and video to a stream in an mpeg format

  I’m tryng to encode video and audio at the same time using Ffmpeg.
  At the moment I’m using this command :

  ffmpeg -r 24 -pix_fmt rgba -s 1280x720 -f rawvideo -y -i -f s16le -ac 1 -ar 44100 -i - -acodec pcm_s16le -ac 1 -b:a 320k -ar 44100 -vf vflip -vcodec mpeg1video -qscale 4 -bufsize 500KB -maxrate 5000KB OUTPUT_FILE

  At first I had this without the information and input from the audio. So, without the audio this works fine :

  ffmpeg -r 24 -pix_fmt rgba -s 1280x720 -f rawvideo -y -i -vf vflip -vcodec mpeg1video -qscale 4 -bufsize 500KB -maxrate 5000KB OUTPUT_FILE

  To write the frames to the encoder (still not using audio) I’m using the following code :

  fwrite(frame, sizeof(unsigned char*) * frameWidth * frameHeight, 1, ffmpeg); 

  Now, I want to add audio to this encoder (see the first command). I added a new input and added the information about the audio to the command but I have no idea how I should write, and when, the audio to the encoder (together with the video).

  I’ve tried this by adding the following code :

  for (int t = 0; t < 44100/24; ++t)
  
      fwrite(&audio, sizeof(short int), 1, ffmpeg);

  This should write 2000 samples of audio per video frame to the encoder. This code is called right after the fwrite() for the video frame.

  This does give weird results however. The image is not rendered in the right spot, gives green flashes and there is no audio.

  I can’t really figure out how (or when) to write the audio to the encoder.

  Thanks in advance !

• Optimizing conversion of video files to texture-atlas

  7 novembre 2017, par Malu05

  I am working on some code that converts a video file into a 1d texture atlas (a single JPG file containing all of the frames stacked on top of each other).
  I do this by reading in the frames using FFMPEG’s image2pipe, and read the pipe into a 3d numpy array. Then use numpy’s concatenate function to add them on top of each other.
  The code itself works fine, but it is somewhat slow. In this example 100 frames of a video takes roughly 15-20 seconds.

  Reading the frames into the pipe is somewhat fast, but reading from the pipe, converting to array and concatenating takes some time.
  I am not too familiar with ways to optimize numpy array handling, but
  I expect that I might be doing something very inefficient here but i can’t seem to spot it. Is there anything i can do to make this process faster ?

  import subprocess as sp
  
  import numpy
  
  import datetime
  
  import matplotlib.pyplot as plt #Only for test plotting.
  
  
  
  FFMPEG_BIN = "ffmpeg" #link to the ffmpeg executeable
  
  
  
  
  
  #Number of images in the texture-atlas
  
  images = 100
  
  
  
  for x in range(0,images): #Loop for each frame to read
  
      res = [596,336,3] #The output format
  
  
  
      #Setup the command for reading 1 frame in the video.
  
      command = [ FFMPEG_BIN,
  
                  '-ss', '%s'%(x),
  
                  '-i', '340114063.mp4',
  
                  '-f', 'image2pipe',
  
                  '-vframes', '1',
  
                  '-vf','scale=%s:%s'%(res[0],res[1]),
  
                  '-pix_fmt', 'rgb24',
  
                  '-vcodec', 'rawvideo', '-']
  
      pipe = sp.Popen(command, stdout = sp.PIPE,stderr=sp.PIPE, bufsize=-1)
  
  
  
      #Read out the image data from the pipe
  
      raw_image = pipe.stdout.read(res[0]*res[1]*res[2])
  
      #Convert to numpy array
  
      image =  numpy.fromstring(raw_image, dtype='uint8')
  
      #Clear the pipe
  
      pipe.stdout.flush()
  
      if x>0:
  
          #Add the image below the last image(s) so that they form a 1d texture atlas
  
          image = numpy.concatenate((last_image,image), axis=0)    
  
      last_image = image
  
  
  
  
  
  #not needed, just for plotting example.
  
  image = image.reshape((res[1]*images,res[0],res[2]))
  
  imgplot = plt.imshow(image)
  
  plt.savefig('foo.png')