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• Imageio python converts GIF to MP4 incorrectly

  1er juin 2018, par Apurva Koti

  I am writing a function to speed up/down a given GIF (or .gifv) file, and save the resulting animation as an .mp4 file.

  I’m using the python imageio package (and its ffmpeg plugin) to do this - download the raw binary data from the gif, write each frame to an mp4, and set the fps of the mp4 to whatever.

  My code is -

  def changespeed(vid, mult):
  
      vid = vid.replace('.gifv', '.gif')
  
      data = urllib2.urlopen(vid).read()
  
      reader = imageio.get_reader(data, 'gif')
  
      dur = (float(reader.get_meta_data()['duration']))
  
      oldfps = 1000.0 / (10 if dur == 0 else dur)
  
  
  
  
  
      writer = imageio.get_writer('output.mp4', fps=(oldfps*mult), quality=8.0)
  
  
  
      for frame in reader:
  
          writer.append_data(frame)
  
      writer.close()

  The problem is, at times the output colors will be heavily corrupted, and there doesn’t seem to be any predictability. This happens with some gifs and doesn’t happen with others. I have tried setting a high quality parameter in the writer but this doesn’t help.

  Here is an example of a problematic GIF -

  Input : https://i.imgur.com/xFezNYK.gif

  Output : https://giant.gfycat.com/MelodicShimmeringBarb.mp4

  I can see this issue locally in output.mp4, so the issue isn’t with uploading to Gfycat.

  Is there anything I can do to avoid this behavior ? Thanks.

• Cannot stream properly on YouTube using ffmpeg with Python

  1er mars 2018, par Francesco

  I have a few problems related to sending ffmpeg stream to YouTube.
  1. If I comment out "time.sleep(sleep_time)" the stream goes 3x fast(basing on what ?) ;
  2. If I uncomment the ’-r’ args the stream lags ;
  3. If I don’t add the background music the stream doesn’t start on YouTube, the problem persists if I uncomment the ’-an’ args.
  4. When the background music ends the stream stops working on YouTube.

  frame = cv2.imread('STATIC_IMAGE.jpg')
  
  fps = 25
  
  sleepTime = 1 / fps
  
  
  
  height, width, channels = frame.shape
  
  
  
  command = [
  
      'ffmpeg',
  
  
  
      #OpenCV image.
  
      #'-re',
  
      #'-threads', '0',
  
      '-f', 'rawvideo', #image2pipe
  
      '-vcodec','rawvideo',
  
      '-s', str(width) + 'x' + str(height),
  
      '-pixel_format', 'bgr24',
  
      #'-r', str(fps),
  
      #'-an',
  
      '-i', '-',
  
  
  
      #Background music
  
      #'-stream_loop', '-1',
  
      #'-re',
  
      #'-r', str(fps),
  
      '-i', 'music.mp3',
  
  
  
      #Output (actual stream)
  
      #'-r', str(fps),
  
      #'-crf', '25',
  
      #'-g', '39',
  
      #'-g', '2',
  
      #'-ac', '2',
  
      #'-c:a', 'aac',
  
      #'-b:a', '128k',
  
      #'-ar', '44100',
  
      #'-an',
  
      #'-b:v', '300k',
  
      #'-c:v', 'libx264',
  
      #'-bufsize', '600k',
  
      #'-maxrate', '300k',
  
      #'-qmin', '32',
  
      #'-qmax', '64',
  
      #'-vcodec', 'libx264',
  
      #'-pixel_format', 'yuv420p',
  
      '-vcodec', 'h264',
  
      '-pixel_format', 'h264',
  
      '-f', 'flv',
  
      'rtmp://a.rtmp.youtube.com/live2/STREAM_KEY'
  
  ]
  
  
  
  import subprocess as sp
  
  proc = sp.Popen(command, stdin=sp.PIPE, shell=False)
  
  
  
  while True:
  
      proc.stdin.write(frame.tostring())
  
  
  
      time.sleep(sleepTime)

  Any idea of why these problems happen ?
  May the "while True" be the problem ?

• FFmpeg GPU build runs slower in Java Runtime

  22 mars 2018, par Raju

  I am writing a Java utility within which I am executing GPU based FFmpeg command (mentioned below). I am using Java Runtime.getRuntime().exec() to achieve this. But the command in Java runtime runs much (4-5 times) slower than executing the same in Linux terminal.

  I couldn’t find the bottleneck in what I am trying to achieve. What is the best way to run an FFmpeg command in Java code ? Any suggestion, guidelines here will be very helpful.

  GPU based FFmpeg command :

  /opt/FFmpeg_GPU/ffmpeg -y -hwaccel cuvid -c:v h264_cuvid -hwaccel_output_format nv12 -vsync 0 -copyts -i sample.mov -map 0 -acodec copy -dn -sn  -vf hwdownload,format=nv12,drawtext=fontfile=/opt/fonts/arial.ttf:text=sample-watermark:fontcolor=white:fontsize=25:box=1:boxcolor=black@0.2:boxborderw=5:x=(w-text_w)/2:y=(h-text_h)/2,format=nv12,hwupload -vcodec h264_nvenc -vprofile main -b:v 1000k -minrate 1000k -maxrate 1000k -bufsize 2000k -sc_threshold 0 -g 50 -keyint_min 50 -cbr 1 -bf 0 -force_key_frames 0 sample.mp4

  Java Code snippet :

  String ffmpegCmd = "/opt/FFmpeg_GPU/ffmpeg -y -hwaccel cuvid -c:v h264_cuvid -hwaccel_output_format nv12 -vsync 0 -copyts -i sample.mov -map 0 -acodec copy -dn -sn  -vf hwdownload,format=nv12,drawtext=fontfile=/opt/fonts/arial.ttf:text=sample-watermark:fontcolor=white:fontsize=25:box=1:boxcolor=black@0.2:boxborderw=5:x=(w-text_w)/2:y=(h-text_h)/2,format=nv12,hwupload -vcodec h264_nvenc -vprofile main -b:v 1000k -minrate 1000k -maxrate 1000k -bufsize 2000k -sc_threshold 0 -g 50 -keyint_min 50 -cbr 1 -bf 0 -force_key_frames 0 sample.mp4"
  
  
  
  Process process = Runtime.getRuntime().exec(ffmpegCmd);
  
  process.waitFor();