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• What resolution would be best for processing videos in firebase functions ? [closed]

  11 janvier 2020, par Nathan

  I’m making an app that is mainly used for sharing videos of maximum 30 seconds long. One video example could be a screen recording of someone’s computer screen or a game. I have this code that checks whether the uploaded video that has just been uploaded to firebase storage has been processed or not and if it hasn’t then I use ffmpeg to process the video (change the resolution etc.) with this command :

  const promise = spawn('./ffmpeg', ['-i', tempFilePath, '-vf', 'scale=1280:720', targetTempFilePath]);

  Now with these commands, the firebase function is giving me a timeout error when I upload 30 second clips since I’m only converting the video to 720. I was just wondering what compression settings would be sufficient enough for the video to :

  1. Be still a high enough quality in my app
  2. Not take ages processing the video in the function (10-20 second clips works perfectly well).

  I know the better option would be to use Googles App engine or something similar to process videos but I’d prefer it to avoid that at the moment, if I can’t process videos to a good enough quality without sacrificing efficiency then I will go to something like Google’s App engine, just need some advice and some pointers for it otherwise.

  EDIT :

  I’ve seen instagram compresses their videos to a resolution of 640x640 ? Would that be reasonable or is it dependent on the original clip’s resolution ?

  Thanks

• lower latency LAN video streaming to Android ? [closed]

  8 janvier 2020, par LargeMoneyBanks

  I am trying to stream desktop video from windows to an Android device on the same network, but seeing huge latency even streaming windows to windows.

  Technically streaming to a unity game using this asset that doesnt support udp but DOES support HTTPS,HTTP,HLS,RTSP,RTMP. https://assetstore.unity.com/packages/tools/video/ump-android-ios-56044

  With some help from a friend I am using ffmpeg for capture, encoding, and streaming with this command :

  .\ffmpeg -threads 8 -f gdigrab -framerate 60 -i desktop -c:v libx264 -refs 3 -g 60 -loglevel debug -pix_fmt yuv420p -slices 8 -an -preset ultrafast -tune zerolatency -f mpegts -listen 1 tcp://0.0.0.0:1234

  Latency is still around 4 seconds even playing the stream on the same PC as hosting, and fiddling with the network cache. Lowering resolution, fps etc doesn’t change latency. This is my first endeavor into optimizing any kind of streaming so I am a little lost. Anyone know what I might be doing wrong or how I can get to at least under 1 second ?

  Thank you !

• ffmpeg convert variable framerate .webm to constant framerate video

  4 novembre 2019, par Dashadower

  I have a .webm file of a recording of a game at 16fps. However, upon trying to process the video with OpenCV, it seems the video is recorded with a variable framerate, so when I try to use OpenCV to get a frame every second by getting the every 16th frame, it won’t work since the video stream will end prematurely.

  Therefore, I’m trying to convert a variable-frame .webm video, which claims it has a framerate of 16 fps, to a video with a constant frame, so I can extract one frame for every second. I’ve tried the following ffmpeg command from https://ffmpeg.zeranoe.com/forum/viewtopic.php?t=5518 :

  ffmpeg -i input.webm -c:v copy -b:v copy -r 16 output.webm

  However, the following error will occur :

  [NULL @ 00000272ccbc0c40] [Eval @ 000000bc11bfe2f0] Undefined constant or missing '(' in 'copy'
  
  [NULL @ 00000272ccbc0c40] Unable to parse option value "copy"
  
  [NULL @ 00000272ccbc0c40] Error setting option b to value copy.
  
  
  
  Error setting up codec context options.

  Here’s is the code I’m trying to use to process a frame every second :

  video = cv2.VideoCapture(test_mp4_vod_path)
  
  print("Opened ", test_mp4_vod_path)
  
  print("Processing MP4 frame by frame")
  
  
  
  # forward over to the frames you want to start reading from.
  
  # manually set this, fps * time in seconds you wanna start from
  
  video.set(1, 0)
  
  success, frame = video.read()
  
  #fps = int(video.get(cv2.CAP_PROP_FPS))  # this will return 0!
  
  fps = 16  # hardcode fps
  
  total_frame_count = int(video.get(cv2.CAP_PROP_FRAME_COUNT))
  
  print("Loading video %d seconds long with FPS %d and total frame count %d " % (total_frame_count/fps, fps, total_frame_count))
  
  
  
  count = 1
  
  while video.isOpened():
  
      success, frame = video.read()
  
      if not success:
  
          break
  
  
  
      if count % fps == 0:
  
          print("%dth frame is %d seconds on video"%(count, count/fps))
  
      count += 1

  The code will finish before it gets near the end of the video, since the video isn’t at a constant FPS.
  How can I convert a variable-FPS video to a constant FPS video ?