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• No such file or directory Error with FFMPEG screenshot and CarrierWave custom model method

  9 juillet 2013, par dodgerogers747

  I am using AWS CORS to upload videos to my site, all of which works as planned.

  I have the following model method which runs as an after_create callback (for speed) to take a screenshot from the video file on AWS. I plan to move this out into a delayed job but I don't think this will solve this particular issue. Please advise if mistaken.

  I use FFMPEG to take a screenshot from the AWS self.file location, I then send the file to CarrierWave by saving the file to self.screenshot where it is uploaded to AWS.

  Approx. 50% of the time it errors out with Errno::ENOENT - No such file or directory for the location of the screenshot image.

  How can I rectify my code to remove this error and how come it only occurs around 50% of the time ? If anyone needs more code just shout.

  video.rb

  after_create :take_screenshot
  
  
  
  mount_uploader :screenshot, ImageUploader
  
  
  
    def take_screenshot
  
      location = "#{Rails.root}/public/uploads/tmp/screenshots/#{unique}_#{File.basename(file)}.jpg"
  
      system `ffmpeg #{log_level} -i #{self.file} -ss 00:00:0#{time_frame} -vframes 1 #{location}`
  
      logger.debug "Trying to take screenshot from #{self.file}"
  
      #pass the actual file to CarrierWave to handle the image upload
  
      self.screenshot = File.open(location)
  
      self.save
  
      logger.debug "Deleting tmp file: #{location}: #{File.delete(location)}" if self.screenshot.present?
  
    end
  
  
  
  def unique
  
      (0..6).map{(65+rand(26)).chr}.join
  
    end
  
  
  
  def log_level
  
      "-loglevel panic"
  
    end
  
  
  
    def time_frame
  
      rand(0..3)
  
    end

  Stack trace :

  Started POST "/videos" for 127.0.0.1 at 2013-07-10 03:58:49 +0800
  
  Processing by VideosController#create as JS
  
    Parameters: {"utf8"=>"✓", "authenticity_token"=>"6M1Ia+Ag2E3HVKH2PO/p7jewxSpMPdWeVHGA933Bzjw=", "video"=>{"file"=>"http://bucketname.s3.amazonaws.com/uploads/video/file/671a87fb-91de-4eaf-a38a-1b25c51798e5/Good_7iron.m4v"}}
  
    User Load (0.3ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 9 LIMIT 1
  
     (0.1ms)  BEGIN
  
    SQL (0.2ms)  INSERT INTO `videos` (`created_at`, `file`, `question_id`, `screenshot`, `updated_at`, `user_id`) VALUES ('2013-07-09 19:58:49', 'http://bucketname.s3.amazonaws.com/uploads/video/file/671a87fb-91de-4eaf-a38a-1b25c51798e5/Good_7iron.m4v', NULL, NULL, '2013-07-09 19:58:49', 9)
  
  Trying to take screenshot from http://bucketname.s3.amazonaws.com/uploads/video/file/671a87fb-91de-4eaf-a38a-1b25c51798e5/Good_7iron.m4v
  
     (0.8ms)  ROLLBACK
  
  Completed 500 Internal Server Error in 3550ms
  
  
  
  Errno::ENOENT - No such file or directory - /Users/me/rails/project/public/uploads/tmp/screenshots/WCACLIC_Good_7iron.m4v.jpg:
  
    app/models/video.rb:24:in `initialize'
  
    app/models/video.rb:24:in `open'
  
    app/models/video.rb:24:in `take_screenshot'

• Get frame from live video stream

  10 avril 2013, par rickster

  I am streaming live video from my camera on my android phone to my computer using the MediaRecorder class.

  recorder.setCamera(mCamera);
  
  recorder.setVideoSource(MediaRecorder.VideoSource.CAMERA);
  
  recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);          
  
  recorder.setOutputFile(uav_UDP_Client.pfd.getFileDescriptor());                     
  
  recorder.setVideoEncoder(MediaRecorder.VideoEncoder.H264);

  That's the basic idea. So I would like to show this stream in real time. My plan is to use FFMpeg to turn the latest frame into a .bmp and show the .bmp on my C# program every time there is a new frame.

  The problem is there is no header until I stop the recording. So I can not use FFMpeg unless there is a header. I've looked at spydroid and using RTP but I do not want to use this method for various reasons.

  Any ideas on how I can do this easily ?

• ffmpeg Live Input MP4 Error [migrated]

  3 mars 2013, par Brianjs

  Currently I have a mic and a webcam connected to my computer. I am running ffmpeg on CentOS 6.3.

  When I try to record a video without audio by :

  ffmpeg -y -f video4linux2 -t 15 -s 640x480 -r 25 -i /dev/video0 /home/irdb/Desktop/out2.mp4

  it runs perfectly and I get a nice video. However when I try to run with audio included by :

  ffmpeg -y -f video4linux2 -t 15 -s 640x480 -r 25 -i /dev/video0 -f alsa -ar 22050 -ab 64k -ac 2 -i default /home/irdb/Desktop/out2.mp4

  It errors out and prints :

  [NULL @ 0x1e33fc0] Codec is experimental but experimental codecs are not enabled,      see -strict -2
  
  Output #0, mp4, to '/home/irdb/Desktop/out2.mp4':
  
  Stream #0:0: Video: h264, yuv420p, 640x480, q=-1--1, 90k tbn, 25 tbc
  
  Stream #0:1: Audio: none, 22050 Hz, 2 channels, flt, 128 kb/s
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (rawvideo -> libx264)
  
  Stream #1:0 -> #0:1 (pcm_s16le -> aac)
  
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such    as bit_rate, rate, width or height

  I assume this has to do with the first error as when I use something like mpg it works just fine. However I plan on streaming this live and want mp4 format as that is pretty much supported by all browsers (Firefox with flash fallback).

  Does anyone know how to get the audio to work without additional processing (as I want to stream live and not write to a file eventually).