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• Rails 5 - Concurrent large Video uploads and FFMPEG encoding in the background is making the server very slow

  8 septembre 2022, par Milind

  I have a working Rails 5 apps using Reactjs for frontend and React dropzone uploader to upload video files using carrierwave.

  



  So far, what is working great is listed below -

  



  

  1. User can upload videos and videos are encoded based on the selection made by user - HLS or MPEG-DASH for online streaming.

  


  2. Once the video is uploaded on the server, it starts streaming it by :-


     

     • FIRST,copying video on /tmp folder.

     


     • Running a bash script that uses ffmpeg to transcode uploaded video using predefined commands to produce new fragments of videos inside /tmp folder.

     


     • Once the background job is done, all the videos are uploaded on AWS S3, which is how the default carrierwave works

     


  


  3. So, when multiple videos are uploaded, they are all copied in /tmp folder and then transcoded and eventually uploaded to S3.

  


  



  My questions, where i am looking some help are listed below -

  



  1- The above process is good for small videos, BUT what if there are many concurrent users uploading 2GB of videos ? I know this will kill my server as my /tmp folder will keep on increasing and consume all the memory, making it to die hard.How can I allow concurrent videos to upload videos without effecting my server's memory consumption ?

  



  2- Is there a way where I can directly upload the videos on AWS-S3 first, and then use one more proxy server/child application to encode videos from S3, download it to the child server, convert it and again upload it to the destination ? but this is almost the same but doing it on cloud, where memory consumption can be on-demand but will be not cost-effective.

  



  3- Is there some easy and cost-effective way by which I can upload large videos, transcode them and upload it to AWS S3, without effecting my server memory. Am i missing some technical architecture here.

  



  4- How Youtube/Netflix works, I know they do the same thing in a smart way but can someone help me to improve this ?

  



  Thanks in advance.

  


• 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.

• avcodec/nvdec : Round up odd width/height values

  24 novembre 2017, par Philip Langdale

  avcodec/nvdec : Round up odd width/height values
  nvdec will not produce odd width/height output, and while this is
  
  basically never an issue with most codecs, due to internal alignment
  
  requirements, you can get odd sized jpegs.
  If an odd-sized jpeg is encountered, nvdec will actually round down
  
  internally and produce output that is slightly smaller. This isn't
  
  the end of the world, as long as you know the output size doesn't
  
  match the original image resolution.
  However, with an hwaccel, we don't know. The decoder controls
  
  the reported output size and the hwaccel cannot change it. I was
  
  able to trigger an error in mpv where it tries to copy the output
  
  surface as part of rendering and triggers a cuda error because
  
  cuda knows the output frame is smaller than expected.
  To fix this, we can round up the configured width/height passed
  
  to nvdec so that the frames are always at least as large as the
  
  decoder's reported size, and data can be copied out safely.
  In this particular jpeg case, you end up with a blank (green) line
  
  at the bottom due to nvdec refusing to decode the last line, but
  
  the behaviour matches cuviddec, so it's as good as you're going to
  
  get.
  

  • [DH] libavcodec/nvdec.c