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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.

  


• I am trying to save frames from a webcam via Python and ffmpeg, but the video becomes way to fast

  10 mai 2022, par Matthias

  I get a stream of cv2 images from my webcam and want to save it to a video file. After playing a bit with cv2.VideoWriter() it turned out that using ffmpeg would provide more options and - apparently, following a few threads here on SO - lead to better results. So I gave the VidGear Python library a try, and it seems to work fine.

  


  There is one catch though : My webcam provides a variable framerate, most of the time between 10 and 30 FPS. When saving these frames the video file becomes way too fast, like watching in fast-forward. One real-time minute becomes only a few seconds in the video.

  


  I tried to play with various combinations of the ffmpeg's -framerate and/or -r parameters, but without luck. Here is the command I am using right now :

  


  ffmpeg -y -f rawvideo -vcodec rawvideo -s 1920x1080 -pix_fmt bgra -framerate 25.0 -i - -vcodec libx265 -crf 25 -r 25 -preset fast 


  


  For the records, I am creating the WriteGear class from the VidGear library like this :

  


  video_params = {
    "-vcodec": "libx265",
    "-crf": 25,
    "-input_framerate": 25,
    "-r": 25,
}
WriteGear(output_filename=video_file, logging=True, **video_params)


  


  Any ideas what I am doing wrong here and how I need to call ffmpeg ?

  


• avfilter/vf_fftdnoiz : Remove redundant ' ;'

  6 mai 2022, par Andreas Rheinhardt

  avfilter/vf_fftdnoiz : Remove redundant ' ;'
  These are actually null statements here and therefore lead
  
  to -Wdeclaration-after-statement warnings.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavfilter/vf_fftdnoiz.c