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• Ream-time watermarking with MPEG-DASH

  14 juillet 2016, par Calvin W.

  In the system, I want to add a unique watermark (e.g. IP address of client and time stamp) into the video that he/she want to watch.

  But when I handled it with OpenCV, it spent 25 minute with a 15-min video. And I need to transcode to mp4 with ffmpeg.

  Now I’m trying the watermark function of ffmpeg, bit it still needs some time.

  It it possible to send the video to client side with MPEG-DASH while transcoding it with ffmpeg ?

  System spec :(Amazon EC2 c3.xlarge)
  Intel Xeon E5-2680 v2 (Ivy Bridge) - 4 vCPU
  7.5G RAM
  40GB SSD
  Ubuntu 14.04 LTS
  OpenCV2.4.13
  ffmpeg 3.1.1
  

  code :

  import cv2
  
  import sys
  
  import time
  
  from datetime import datetime as dt
  
  
  
  # frame of input video
  
  fps = float(sys.argv[4])
  
  # encode to AVC
  
  fourcc = cv2.cv.CV_FOURCC('A', 'V', 'C', '1')
  
  # transparency of text
  
  alpha = 0.1
  
  beta = 1 - alpha
  
  
  
  # input video
  
  cap = cv2.VideoCapture(sys.argv[3])
  
  
  
  # current frame index, start from 0
  
  frameIndex = 0
  
  
  
  # get input video's width/height
  
  width = int(cap.get(cv2.cv.CV_CAP_PROP_FRAME_WIDTH))
  
  height = int(cap.get(cv2.cv.CV_CAP_PROP_FRAME_HEIGHT))
  
  
  
  # config output (error using .mp4)
  
  out = cv2.VideoWriter('output.avi', fourcc, fps, (width, height))
  
  
  
  # access time
  
  timeStr = dt.fromtimestamp(time.time()).strftime('%Y-%m-%d %H:%M:%S')
  
  
  
  requestIP = sys.argv[1]
  
  username = sys.argv[2]
  
  text = "%s %s %s" % (requestIP, username, timeStr)
  
  
  
  
  
  # start loading video
  
  while(cap.isOpened()):
  
      ret, frame = cap.read()
  
      if ret:
  
          # add text between 10s - 20s
  
          if frameIndex > time10 and frameIndex < time20:
  
              # clone a new frame to add text
  
              overlay = frame.copy()
  
              cv2.putText(overlay, text, (100, 100), cv2.FONT_HERSHEY_PLAIN, 0.5, (255, 255, 255))
  
              # combine both frame and make text transparent
  
              cv2.addWeighted(overlay, alpha, frame, beta, 0, frame)
  
          # write frame to output
  
          out.write(frame)
  
          frameIndex += 1
  
      # wait for next frame
  
      if cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES) == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
  
          break
  
  # End of video
  
  # release
  
  cap.release()
  
  out.release()

• How to record (and process ?) a video that is streamable from Android

  13 mai 2016, par afollestad

  My company’s app relies heavily on video recording and playback of web-based videos. I use the MediaRecorder API to record videos, through this library designed by me : https://github.com/afollestad/material-camera.

  For playback, I use this library which is basically a wrapper around Google’s ExoPlayer library : https://github.com/brianwernick/ExoMedia.

  It works fine for the most part with small videos, especially if I decrease bit rates for audio and video. However, larger and higher quality videos have many issues. Sometimes they seem to buffer forever, sometimes playback doesn’t even start successfully, etc. Again, these videos are being streamed over HTTP from Amazon S3.

  ---

  I’ve read a little bit about FFMPEG, and how it can process MP4’s for "faststart", splitting the files into chunks for DASH, etc. However, FFMPEG solutions for Android seem a bit complex, so...

  Is there anyway to record MP4’s from Android, with MediaRecorder, MediaCodec, or some other API which results in a video file that is fast to stream ? It amazes me how well Snapchat has figured this out.

• rails streamio-ffmpeg does not find uploaded video files

  26 avril 2016, par Felix

  I try to make a screenshot as thumbnail of a movie while uploading.

  My code looks like this at the moment

  require 'rubygems'
  
  require 'streamio-ffmpeg'
  
  
  
   def uploadMovie
  
     @channels = Channel.all
  
     @vid = Movie.new(movies_params)
  
  
  
     @channel = Channel.find(params[:vid][:channel_id])
  
     @vid.channel = @channel
  
  
  
     if @vid.save
  
       flash[:notice] = t("flash.saved")
  
       movieFile = FFMPEG::Movie.new(@vid.video.to_s)
  
       screenshot = movieFile.screenshot("uploads/screenshot", :seek_time => 10)
  
       render :add
  
     else
  
       render :add
  
     end
  
   end

  But when I do this I got this error :

    No such file or directory - the file 'http://.s3.amazonaws.com/uploads/movie/video/7/2016-04-24_16.26.10.mp4' does not exist

  That should be okay because I upload the movies to Amazon S3 with carrierwave ...

  What’s going wrong in this case ?