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• images->video->web canvas : RGB/YUV issues

  5 février 2016, par nrob

  We’ve written an web app which :

  1. takes 3D, time dependent weather data
  2. tiles each 3D time point to make a 2D frame (written out as a png image)
  3. stitches these frames together into a video (using ffmpeg/avconv)
  4. streams this video into a web app
  5. polls the canvas for frames
  6. sends the frames to the GPU where they are converted back to 3D and ray traced

  You can see the app here, code here and you can see the data video here

  Currently the pngs are written as RGB images, the video codec is in YUV and getting frames from the canvas returns RGB. As such there is a significant loss of information due to the conversion between image spaces.

  Does anyone have suggestions what is the best way round this ?

  I’ve tried a bunch of RGB video codecs, but I can’t get any to work, and I don’t know if the web browser will support it anyway. Can anyone suggest a good RGB codec (both lossy and lossless would be great)

  Also, is it possible to write to YUV images/read them from a video canvas in HTML5 ?

  Ultimately, I don’t even want anything to do with images/videos, I’m just hacking the codecs to stream/compress large animated 3D data volumes

• Stream video and commands on same connection or split connections ?

  10 mai 2013, par bizzehdee

  Background

  I am in the middle of writing a client/server app that i will install on every machine within my office (roughly 30 - 35 machines). I currently have the client connecting to the server and it has an ability to send mouse movement, mouse clicks, key strokes and execute certain commands. The next step is to stream back a video output of the screen, i am using the GDI method from Fastest method of screen capturing to capture the entire screen and will be using the x264 encoder to compress the frames and transmit them back to the client which will then decode and display the stream.

  Question

  is it best (by means of reducing lag, ensuring all commands are delivered as fast as possible and that streaming is as live as possible) that i transmit back along the same connection that i established for the commands, or, should i establish a separate connection on the same port, or on a different port to stream back the video ?

  P.S.

  i am aware that VNC, RD and other things such as TeamViewer already exist and already do this sort of thing, but none of these support all the requirements needed for what we need within this system.

• batch FOR loop with FFMPEG

  27 décembre 2014, par user3604398

  I want to divide a .mp4 file into smaller .mp4 clips using ffmpeg.

  This is the code without a loop :

  ffmpeg -i source-file.mp4 -ss 0 -t 600 first-10-min.mp4
  
  ffmpeg -i source-file.mp4 -ss 600 -t 600 second-10-min.mp4
  
  ffmpeg -i source-file.mp4 -ss 1200 -t 600 third-10-min.mp4
  
  ...

  How do I make it into a loop in Microsoft DOS ? So far I have this :

  for /r $i in (*.mp4) do "C:\Program Files\FFMPEG\bin\ffmpeg.exe" -i "C:\Users\Name\Videos\2014-12-27-0926-45.mp4" -ss 0 -t 600

  Also someone said to put -codec copy in somewhere but I don’t know where.