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• Use a video editing library (not executable) via Node [on hold]

  25 septembre 2018, par Merc

  I need to edit clips using node. I am looking around, and most (if not all) libraries seem (like Fluent FFMpeg) seem to be based on the fact that they run FFMPEG as an executable and get the resulting output.

  That’s not what I want. I worked with FFMPEG executable in the past, and I know how flaky it is in terms of return codes and error codes.

  Ideally, I would love to find a native library for video editing and make calls using node.

  In terms of libraries :

  • Gstreamer
  • FFmpeg/LibAV (does they come with C libraries to bind to ?)
  • libVLC

  In terms of binding with them :

  • node-gir. Gstreamer seems to have updated git files

  • native bindings. For example Gstreamer has gstreamer-superficial. I couldn’t find any javascript bindings forFFMPEG — only "run the executable and hope for the best" libraries

  • VLC has a bindings library that is quite old and had its last commit years ago.

  Am I getting this all wrong ?
  My ideal outcome is to have a nice, robust library that I use directly using node, but my lack of experience in terms of using native libraries, and the somehow fragmented world of video editing libraries.

• Elixir long running background task doesn't complete, sometimes crashes

  29 mars 2018, par Kulix

  As a little bit of background, I have an endpoint that is responsible for video upload. What I want to do, is copy the video file to a temporary location from the request, and spin up an asynchronous task (ffmpeg shell process) to transcode that video in the background so that my endpoint can return a 200 in a timely manner, and the response does not wait for ffmpeg to finish transcoding that video.

  Here is my code from the controller.

  def create(conn, %{"file" => file ... })
  
      uuid = Video.uuid()
  
      tmp_path = Application.get_env(:myapp, :video_tmp_path) <> "/" <> uuid
  
      :ok = File.cp(file.path, tmp_path)
  
      VideoService.process(tmp_path, final_path)

  The inside of VideoService looks like the following.

  defmodule MyApp.Services do
  
    defmodule VideoService do
  
      def process(tmp_path, final_path) do
  
        Task.start_link fn ->
  
          System.cmd("ffmpeg", ["-i", tmp_path, final_path, "-hide_banner"])
  
          File.rm(tmp_path)
  
        end
  
      end
  
    end
  
  end

  The problem I am having here is that no matter what, nothing past the System.cmd("ffmpeg") call executes in the VideoService, and sometimes the System.cmd call doesn’t even spin up an ffmpeg process. Am I doing something wrong here ? What I need is a way to spin this ffmpeg shell process out in the background from the controller / service and respond with a 200 on video upload. Thanks for help in advance. I am new to elixir / OTP, so I’m sure I’m doing something stupid.

  I also randomly see the following error

  erl_child_setup: failed with error 32 on line 240

• How to get iOS App Preview video bitrate in range

  29 avril 2019, par JKaz

  Creating new App Previews for App Store Connect has always been difficult. Time to do it again (new app version) and running into same issue without resolution this time.

  Making the video is easy enough, recording it with Quicktime and either a connected device or through Simulator (and the xcrun simctl io booted recordVideo <filename>.<file extension="extension"></file></filename> Terminal command).

  I can open that in iMovie, create a new App Preview, and export/share the preview with proper size, length, frame rate per Apple specs. But the bit rate is always too low ( 4 mbps) and it’s required to be 10-12 mbps (and I’ve had video reject be/c of that). In the past I could always make some change to the .mp4, in conjunction with something like ffmpeg -i ~/appVideo.mp4 -b:v 11M ~/appPreview.mp4 to get the file into the target range, but that’s not helping today, and neither is Developer Tech Support.

  Apple’s documentation says :

  To export the final video, click Share in the toolbar, then choose App
  Preview. The export settings are automatically configured to meet App
  Store requirements. iMovie exports the final video at the correct
  resolution based on the device from which your clips were captured.

  I’ve done that and more, and bit rate is still out of range (every other attribute is in spec). I’ve tried the recommendations from a bunch of other threads here for http://video.online-convert.com/convert-to-mp4 and others, and none seem to do the trick. Am I missing something obvious re bitrate ? Is it this hard for everyone ?

  Thank you.