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• Streaming audio file conversion process

  11 janvier 2017, par YAL

  I am integrating IBM Speech to Text API to my Django project. The problem that I have right now is that we allow users to upload audio files and majority of them are in the format of MP3 or MP4. However, the API only takes FLAC or WAV format.

  I am currently using FFMPEG for file conversion. However, this audio conversion library loads the entire audio file in memory as opposed to doing it in chunks.

  I wonder what would be a good solution to this problem or other packages that I should use ?

• No such file or directory Error with custom FFMPEG + CarrierWave method

  10 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'

• ffmpeg cut the video and get accurate begining time of the result

  1er décembre 2022, par Pavlo Sharhan

  I do the cut via :

  


  ffmpeg -i  long_clip.mp4 -ss 00:00:10.0 -c copy -t 00:00:04.0 short_clip.mp4


  


  I need to know the precise time where did the ffmpeg do the cut (Time of the closest keyframe before the 00:00:10.0)

  


  Currently, I'm using the following ffprobe command to list all the keyframes and select the closest before 00:00:10.0

  


  ffprobe -show_frames -skip_frame nokey long_clip.mp4


  


  It works extremely slow (I run It on Jetson Nano, and It is a few minutes to list the keyframes for 30 sec video, although the cutting is done in 0.2seconds)

  


  I hope there is the much faster way to know the time of the keyframe where ffmpeg does the cut, at least because ffmpeg seeks to this keyframe and cuts the video less than in half a second.

  


  So in other words the question is : How to get the time of the keyframe where ffmpeg does the cut not listing all the keyframes ?