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• FFMpeg Command work in command line, but not in python script

  20 février 2015, par Fooldj

  Okay, kind of a weird problem. But I’m not sure whether it’s python, ffmpeg, or some stupid thing I’m doing wrong.

  I’m trying to take a video, and take 1 frame a second, and output that frame to an image. Right now, if i use the command line with ffmpeg :

  ffmpeg -i test.avi -r 1 -f image2 image-%3d.jpeg -pix_fmt rgb24 -vcodec rawrvideo

  It outputs about 10 images, the images look fine, awesome. Now I have this code (right now some code from some github, as I wanted stuff that i was relatively sure would work, and mine is allll convoluted)

  import subprocess as sp
  
  import numpy as np
  
  import re
  
  import cv2
  
  import time
  
  
  
  FFMPEG_BIN = r'ffmpeg.exe'
  
  INPUT_VID = 'test.avi'
  
  
  
  def getInfo():
  
      command = [FFMPEG_BIN,'-i', INPUT_VID, '-']
  
      pipe = sp.Popen(command, stdout=sp.PIPE, stderr=sp.PIPE)
  
      pipe.stdout.readline()
  
      pipe.terminate()
  
      infos = pipe.stderr.read()
  
      infos_list = infos.split('\r\n')
  
      res = re.search(' \d+x\d+ ',infos)
  
      res = [int(x) for x in res.group(0).split('x')]
  
      return res
  
  res = getInfo()
  
  command = [ FFMPEG_BIN,
  
          '-i', INPUT_VID,
  
          '-f', 'image2pipe',
  
          '-pix_fmt', 'rgb24',
  
          '-vcodec', 'rawvideo', '-']
  
  pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=10**8)
  
  n = 0
  
  im2 = []
  
  try:
  
      mog = cv2.BackgroundSubtractorMOG2(120,2,True)
  
      while True:
  
          raw_image = pipe.stdout.read(res[0]*res[1]*3)
  
          # transform the byte read into a numpy array
  
          image =  np.fromstring(raw_image, dtype='uint8')
  
          image = image.reshape((res[1],res[0],3))
  
          rgbImg = image.copy()
  
  
  
          fname = ('_tmp%03d.png'%time.time())
  
          cv2.imwrite(fname, rgbImg)
  
          # throw away the data in the pipe's buffer.
  
          #pipe.stdout.flush()
  
          n += 1
  
          print n
  
  except:
  
      print 'done',n
  
      pipe.kill()
  
      cv2.destroyAllWindows()

  When I run this, I get 10 images, but they all have a Blue Tint ! I cannot for the life of me figure out why. I’ve done tons of searches, I’ve tried quite a few different codecs (usually just messes things up worse). The media info for the video file is here :

   General
  
   Complete name                            : test.avi
  
  Format                                   : AVI
  
  Format/Info                              : Audio Video Interleave
  
  File size                                : 85.0 KiB
  
  Duration                                 : 133ms
  
  Overall bit rate                         : 5 235 Kbps
  
  
  
  Video
  
  ID                                       : 0
  
  Format                                   : JPEG
  
  Codec ID                                 : MJPG
  
  Duration                                 : 133ms
  
  Bit rate                                 : 1 240 Kbps
  
  Width                                    : 640 pixels
  
  Height                                   : 480 pixels
  
  Display aspect ratio                     : 4:3
  
  Frame rate                               : 30.000 fps
  
  Color space                              : YUV
  
  Chroma subsampling                       : 4:2:2
  
  Bit depth                                : 8 bits
  
  Compression mode                         : Lossy
  
  Bits/(Pixel*Frame)                       : 0.135
  
  Stream size                              : 20.1 KiB (24%)

  Any suggestions ? It seems like it should be an RGB mixup...just not sure where at...

• FFmpeg : encoding in webm (vp9) for windows

  2 juillet 2015, par Seltymar

  I’m trying to encode jpegs to a webm video in vp9 on windows 7.

  I followed the instructions from webmproject in 2 pass.
  I changed \dev\nul by NUL.

  ffmpeg.exe -i %4d.jpg -c:v libvpx-vp9 -pass 1 -b:v 1000K -threads 8 -speed 4 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -an -f webm NUL
  
  
  
  ffmpeg.exe -i %4d.jpg  -c:v libvpx-vp9 -pass 2 -b:v 1000K -threads 8 -speed 1 -tile-columns 6 -frame-parallel 1 -auto-alt-ref 1 -lag-in-frames 25 -c:a libopus -b:a 64k -f webm out.webm

  but after the first pass, it tells me "output file is empty, nothing was encoded". But the second pass create the video.

  I also tryed in one pass :

  ffmpeg -i %4d.jpg -c:v libvpx-vp9 -crf 10 -b:v 0 output.webm

  Then I want to use the output video using html5 video and canvas tags as below.

      
  
  
  
  
  
  
  
  
  
  <canvas>
  
          Your browser does not support the canvas tag.
  
  </canvas> 
  
  <code class="echappe-js">&lt;script&gt;<br />
  
  <br />
  
  <br />
  
          var videos = document.createElement('video');<br />
  
          videos.src = &quot;output.webm&quot;;<br />
  
          videos.type = &quot;video/webm&quot;;<br />
  
          videos.load(); <br />
  
          videos.play();<br />
  
          videos.playbackRate = 1;<br />
  
          var videoImage0 = document.getElementById('canvas');        <br />
  
          videoImage0.width = 2700;<br />
  
          videoImage0.height = 1350;<br />
  
  <br />
  
          var videoImageContexts =videoImage0.getContext('2d');<br />
  
          //// background color if no video present<br />
  
          videoImageContexts.fillStyle = '#0000ff';<br />
  
          videoImageContexts.fillRect(0, 0, videoImage0.width, videoImage0.height);       <br />
  
          animate();<br />
  
  <br />
  
      function animate() {<br />
  
          requestAnimationFrame(animate);<br />
  
          update();<br />
  
  <br />
  
      }<br />
  
  <br />
  
      function update() {<br />
  
  <br />
  
          if (videos.readyState === videos.HAVE_ENOUGH_DATA) {<br />
  
              videoImageContexts.drawImage(videos, 0, 0);<br />
  
          }<br />
  
      }<br />
  
  &lt;/script&gt;
  

  result :

  1. With both methods the output video can’t be read in VLC but it can be read if I drag and drop in firefox or chrome or using the video tag only.
  2. The html page above works correctly on chrome but not in firefox. In firefox, the color is not correct like if the blue channel was translated.
     

  I think the problem is the encoding with FFmpeg. I’m using the static build from zeranoe. Here is the version

  and libvpx is enable.

  My questions :

  • Is there a problem on my command line ?

  • Is there a problem in my JS code that could lead to error in the decoding process ?

• Trying to encode video file as hevc error in python

  29 juin 2022, par jatt

  I am getting a syntax error when trying to run this code with it saying the end quotes being the error. process = sp.Popen(shlex.split(f'usr/bin/ffmpeg -y -s {width}x{height} -pixel_format bgr24 -f rawvideo -r {fps} -i pipe: -vcodec libx265 -pix_fmt yuv420p -crf 24 {output_filename}') stdin=sp.PIPE)

  


  I don't know why because the end quote is supposed to be there and I am not sure how to fix it.
The original code is from here : How to output x265 compressed video with cv2.VideoWriter

  


  import cv2
import numpy as np
import subprocess as sp
import shlex

width, height, n_frames, fps = 1344, 756, 50, 25  # 50 frames, resolution 1344x756, and 25 fps

output_filename = 'output.mp4'

# Open ffmpeg application as sub-process
# FFmpeg input PIPE: RAW images in BGR color format
# FFmpeg output MP4 file encoded with HEVC codec.
# Arguments list:
# -y                   Overwrite output file without asking
# -s {width}x{height}  Input resolution width x height (1344x756)
# -pixel_format bgr24  Input frame color format is BGR with 8 bits per color component
# -f rawvideo          Input format: raw video
# -r {fps}             Frame rate: fps (25fps)
# -i pipe:             ffmpeg input is a PIPE
# -vcodec libx265      Video codec: H.265 (HEVC)
# -pix_fmt yuv420p     Output video color space YUV420 (saving space compared to YUV444)
# -crf 24              Constant quality encoding (lower value for higher quality and larger output file).
# {output_filename}    Output file name: output_filename (output.mp4)
process = sp.Popen(shlex.split(f'usr/bin/ffmpeg -y -s {width}x{height} -pixel_format bgr24 -f rawvideo -r {fps} -i pipe: -vcodec libx265 -pix_fmt yuv420p -crf 24 {output_filename}') stdin=sp.PIPE)

# Build synthetic video frames and write them to ffmpeg input stream.
for i in range(n_frames):
    # Build synthetic image for testing ("render" a video frame).
    img = np.full((height, width, 3), 60, np.uint8)
    cv2.putText(img, str(i+1), (width//2-100*len(str(i+1)), height//2+100), cv2.FONT_HERSHEY_DUPLEX, 10, (255, 30, 30), 20)  # Blue number

    # Write raw video frame to input stream of ffmpeg sub-process.
    process.stdin.write(img.tobytes())

# Close and flush stdin
process.stdin.close()

# Wait for sub-process to finish
process.wait()

# Terminate the sub-process
process.terminate()