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• Record Sound on Ubuntu Docker Image

  21 avril 2020, par Daniel Rasmuson

  I would like record audio with ffmpeg when I capture my screen. The error I'm getting when using alsa is that is that my image does not have a sound card -f alsa -ac 2 -i hw:0

  



  Here is how to reproduce on a fresh version of Ubuntu

  



  Start a session in a new ubuntu docker image.

  



  docker pull ubuntu
docker run -it --rm ubuntu


  



  Setup alsa (Advanced Linux Sound Architecture)

  



  apt-get update
apt-get install alsa-utils


  



  List the sound cards

  



  aplay -l
# aplay: device_list:268: no soundcards found...


  



  And playing this sound will fail because this image doesn't have any sound cards

  



  sudo aplay /usr/share/sounds/alsa/Front_Center.wav


  


• configure : Do not abort when cross-compiling to the native CPU

  1er avril 2020, par David Michael

  configure : Do not abort when cross-compiling to the native CPU
  Using a compiler with a different host triplet is considered
  
  cross-compiling, even when it is for the same architecture as the
  
  build system.  With such a cross-compiler, it is still valid to
  
  optimize builds with —cpu=host.  Make the condition that aborts in
  
  this case into a warning instead, since a cross-compiler for an
  
  incompatible architecture will fail with -mtune=native anyway.
  Signed-off-by : David Michael <fedora.dm0@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] configure

• 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.