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• Speeding up videocomposing in pymovie

  10 février 2024, par rawlung

  I'm trying to resize videos similarly to what this api provides
https://creatomate.com/docs/json/quick-start/blur-video-background
I accomplished the result more or less but the problem is it takes ages to render out.
I'm a total beginner when it comes to video processing and for the life of me i can't figure out how to speed it up. When the rendering is running python only uses CPU at about 20% utilization.

  


  from moviepy.editor import VideoFileClip, concatenate_videoclips,CompositeVideoClipimport datetimefrom skimage.filters import gaussian

def _blur(image):
  return gaussian(image.astype(float), sigma=25,preserve_range=True,channel_axis=-1)

def blurVideos(filenames):
  clips = [VideoFileClip(c) for c in filenames]
  overlay_clips = [VideoFileClip((c), has_mask=True) for c in filenames]
  overlay = concatenate_videoclips(overlay_clips,"chain")
  output = concatenate_videoclips(clips, method="chain")
  print("Bluring video")
  blured_output = output.fl_image( _blur )
  print("Done")
  print("Resizing video")
  resized_output = blured_output.resize((1920,1080))
  print("Done")
  composited_output = CompositeVideoClip([resized_output.without_audio(),overlay.set_position("center","center")])
  composited_output.write_videofile(f"output/out_{datetime.datetime.today().strftime('%Y-%m-%d')}.mp4",fps=20,threads=16,codec="h264_nvenc",preset="fast")


  


  I've tried to use GPU accelerated codecs like h264_nvenc, I've tried to modify ffmpeg arguments under the hood of moviepy to use cuda also no succses
What can i do to speed this up ?

  


• Calling ffmpeg from command line does not wait until file was fully written do hard drive

  10 octobre 2020, par Stefan Falk

  I am currently working on a service to allower conversion of audio files. I am using ffmpeg under the hood and use the Runtime in order to make the call.

  


  After the call I read the converted file and upload it to a cloud storage.

  


  The problem :

  


  The problem is, that reading the file back from the drive gives me only a few bytes. After investigating, it actually has like 5 MB on the drive but readFileToByArray() reads only a few kb. I assume this is because the file was not completely persisted at the point where I want to read it back.

  


  Is there any way I can make sure that ffmpeg is done writing to the hard drive ? It seems that the main process that ffmpeg was running in finishes before a parallel process that is responsible for writing. Maybe ?

  


  Below is the relevant code that converts an arbitrary file to AAC-format :

  


  File tempFile = File.createTempFile("input-", ".tmp", new File("/tmp"));
OutputStream outStream = new FileOutputStream(tempFile);
outStream.write(bytes);

String convertedFilePath = String.format("/tmp/output-%s.aac", UUID.randomUUID().toString());

String command = String.format(
        "ffmpeg -i %s -c:a aac -b:a 256k %s",
        tempFile.getAbsolutePath(),
        convertedFilePath
);

LOGGER.debug(String.format("Converting file to AAC; Running %s", command));

Runtime runtime = Runtime.getRuntime();
Process process = runtime.exec(command);
try {
    process.waitFor(200, TimeUnit.MILLISECONDS);
} catch (InterruptedException e) {
    throw new RuntimeException("Time out");
}

File convertedFile = new File(convertedFilePath);
byte[] result = FileUtils.readFileToByteArray(convertedFile);

// Upload "result" to cloud storage ..


  


• FFmpeg/OpenCV force ignore input frame duration with rtsp ?

  6 août 2019, par ZisIsNotZis

  I was experiencing a ~5 sec delay when playing a rtsp stream from an IP camera. After a bunch of googling (especially this question), I reduced the delay to ~1 sec using the following command :

  ffplay -fflags nobuffer -flags low_delay -framedrop -strict experimental \
  
         -probesize 32 -sync ext rtsp://xxx.xxx.xxx.xxx

  But when I tried mplayer -benchmark command from the same question, I found the delay immediately goes away (i.e. almost 0 delay).

  In the man page of mplayer, it sais :

  -benchmark

  Prints some statistics on CPU usage and dropped frames at the end of playback. Use in combination with -nosound and -vo null for benchmarking only the video codec.

  NOTE : With this option MPlayer will also ignore frame duration when playing only video (you can think of that as infinite fps).

  I feel this "ignore frame duration" is the key to the question, but after a bunch of googling, I didn’t find any flag related to this in ffmpeg. I’m wondering how to force ignore input frame duration in ffmpeg ?

  On the other hand, the reason I’m using ffmpeg is because I need to do image processing using opencv, while I found it seems to be using some part of ffmpeg under-the-hood when doing

  cv.VideoCapture('rtsp://xxx.xxx.xxx.xxx')

  A solution that directly solves the problem in opencv would be even more appreciated. I did try reading the VideoCapture repeatedly in a separate thread, that didn’t help.

  ---

  Some info about the RTSP stream : h264, 1920x1080, 15fps, 1 key frame per 4s

  Some other solutions I tried :

  ffmpeg -r 99999 -i ...
  
  # didn't work
  
  
  
  mplayer ... -dumpstream
  
  # it core dumped