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• Media conversion on AWS

  27 juin 2022, par Gurmeet Singh

  I have an API written in nodeJS (/api/uploadS3) which is a PUT request and accepts a video file and a URL (AWS s3 URL in this case). Once called its task is to upload the file on the s3 URL.

  


  Now, users are uploading files to this node API in different formats (thanks to the different browsers recording videos in different formats) and I want to convert all these videos to mp4 and then store them in s3.

  


  I wanted to know what is the best approach to do this ?

  


  I have 2 solutions till now

  


  1. Convert on node server using ffmpeg -

  


  The issue with this is that ffmpeg can only execute a single operation at a time. And since I have only one server I will have to implement a queue for multiple requests which can lead to longer waiting times for users who are at the end of the queue. Apart from that, I am worried that during any ongoing video conversion if my node's traffic handling capability will be affected.

  


  Can someone help me understand what will be the effect of other requests coming to my server while video conversion is going on ? How will it impact the RAM, CPU usage and speed of processing other requests ?

  


  2. Using AWS lambda function -

  


  To avoid load on my node server I was thinking of using an AWS lambda server where my node API will upload the file to S3 in the format provided by the user. Once, done s3 will trigger a lambda function which can then take that s3 file and convert it into .mp4 using ffmpeg or AWS MediaConvert and once done it uploads the mp4 file to a new s3 path. Now I don't want the output path to be any s3 path but the path that was received by the node API in the first place.

  


  Moreover, I want the user to wait while all this happens as I have to enable other UI features based on the success or error of this upload.

  


  The query here is that, is it possible to do this using just a single API like /api/uploadS3 which —> uploads to s3 —> triggers lambda —> converts file —> uploads the mp4 version —> returns success or error.

  


  Currently, if I upload to s3 the request ends then and there. So is there a way to defer the API response until and unless all the operations have been completed ?

  


  Also, how will the lambda function access the path of the output s3 bucket which was passed to the node API ?

  


  Any other better approach will be welcomed.

  


  PS - the s3 path received by the node API is different for each user.

  


• record screen with high quality and minimum size in ElectronJS (Windows)

  4 avril 2022, par Seyed Ali Roshan

  as I said in the title, I need to record my screen from an electron app.

  


  my needs are :

  


  

  • high quality (720p or 1080p)

  


  • minimum size

  


  • record audio + screen + mic

  


  • low impact on PC hardware while recording

  


  • no need for any wait after the recorder stopped

  


  


  


  by minimum size I mean about 400MB on 720p and 700MB on 1080p for a 3 to 4 hours recording. we already could achieve this by bandicam and obs and it's possible

  


  


  I already tried :

  


  

  • the simple MediaStreamRecorder API using RecordRTC.Js ; produces huge file sizes, like 1GB per hour for 720p video.

  


  • compressing the output video using FFmpeg ; it can take up to 1 hour for 3 hours recording

  


  • save every chunk with 'ondataavailable' event and right after, run FFmpeg and convert and reduce the size and append all the compressed files (also by FFmpeg) ; there are two problems. 1, because of different PTS but it can be fixed by tunning compress command args. 2, the main problem is the audio data headers are only available in the first chunk and this approach causes a video that only has audio for the first few seconds

  


  • recording the video with FFmpeg itself ; the end-users need to change some things manually (Stereo Mix), the configs are too complex, it causes the whole PC to work slower while recording (like fps drop ; even if I set -threads to 1), in some cases after recording is finished it needs many times to wrap it all up

  


  • searched through the internet to find applications that can be used from the command line ; I couldn't find much, the famous applications like bandicam and obs have command line args but there are not many args to play with and I can't set many options which leads to other problems

  


  


  I don't know what else I can do, please tell me if u know a way or simple tool that can be used through CLI to achieve this and guide me through this

  


• FFmpeg vidstab generates jerky wiggling video

  27 mars 2022, par praet0ri4n

  I run Kdenlive 21.12.3 on Ubuntu 20.04.
Recently I stared editing footage from my Nikon D3100 DSLR. Source videos are 1920:1080 24fps in MOV format (camera set to PAL system).

  


  After trying to stabilize a video where I am walking I noticed that the result is kind of stabilized but the image is distorted and contains some strange wiggling effect. Changing the stabilization settings doesn't have any impact on this effect. I haven't seen this before. Previously I stabilized footage from other cameras without problems. This is the first time I use that DSLR.

  


  To me it looks like stabilization is doing some strange interpolation and it is stretching and skewing the image or pixel aspect ratio.
For convenience I tried the vidstab filter with ffmpeg, played around with the interpol option too, but the result ist exactly the same.

  


  Here the source MOV and stabilized mp4 file for comparison
https://nc.p1p0.eu/index.php/s/tTQgPj9rDbmReYn

  


  Thank you !