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• Creating a video from data of server-side script

  8 mars 2016, par Peter Leupold

  My plan is to display the data that a server-side script generates in a video displayable on my web page. So far my approach is the following :

  1. A three dimensional integer array in a C script is use to accumulate the image data. Dimensions are width, breadth and color (R, G and B).
  2. The array is written to a ppm-file.
  3. The next picture is accumulated and written and so on.
  4. With ffmpeg a script merges the ppm-files to a mp4-video.

  Basically this works, but of course faster would be nicer. I would appreciate proposals for fundamentally different approaches as well as help on the following details :

  • Is there a file format simple as ppm that uses the HEX code for colors instead of triplets ? This would reduce the size of my array as well a the number of write operations.
  • Do I loose much time if I print every single value to the file with an fprintf operation instead of accumulating lines into a string ? Or do compilers optimize this kind of sequences of writes ?

• generating a video mosaic in client-side js

  1er novembre 2020, par redbrain

  I'm writing a web app for the creation of mosaic videos, where multiple videos can tiled next to each other, like a virtual meeting or grid of surveillance cameras. I'd like the user to be able to download their creation as an video file.

  


  I've currently been accomplishing this using a Node.js server to serve the rest of the site (which is static html/js) and then having one route execute ffmpeg and return the result. However, if this can be accomplished on the client side, the app would be easier to scale since I'd only have to serve static files, and nicer to write with only the client-side in mind.

  


  Does anyone know of a proper or clean way to do this ? I've looked at the following methods so far :

  


  

  • using ffmpeg ported to webassembly - this seems to be used constantly for any sort of client-side video editing ; however it seems overkill and clunky for this purpose

  


  • tiling all the videos in a <canvas></canvas> and rendering its output to an mp4 via the MediaStreamAPI - could be the best way, but it's not well documented

  


  


  If I'm missing something obvious, please let me know. I figured I would look further for the best method before writing further. Thanks in advance.

  


• Using ffmpeg with Flash Media Server and HDS

  20 avril 2012, par Jonathan

  I want to use ffmpeg to encode and publish a live stream to Flash Media Server. In order to support iOS devices, I need to implement HTTP Live Streaming as well. The video needs to be in H.264 format and the audio should be AAC. I don't have much experience working with ffmpeg, and I'm having a hard time getting this to work. This is the command that I've tried (and some variations as well) :

  ffmpeg.exe -threads 15 -f dshow -i video="USB2.0 UVC WebCam":audio="Microphone (Realtek High Defini" \
  
        -map_channel 0.1.1 -r 24 -acodec libvo_aacenc -ar 22050 -ab 128k -vcodec libx264 \
  
        -s vga -vb 100k -f flv "rtmp:///livepkgr/livestream1?adbe-live-event=liveevent" \
  
        -r 24 -acodec libvo_aacenc -ar 22050 -ab 128k -vcodec libx264 -s qvga -vb 200k \
  
        -f flv "rtmp:///livepkgr/livestream2?adbe-live-event=liveevent" \
  
        -r 24 -acodec libvo_aacenc -ar 22050 -ab 128k -vcodec libx264 -s vga -vb 350k 
  
        -f flv "rtmp:///livepkgr/livestream3?adbe-live-event=liveevent"

  When I run this, it appears to connect to FMS, but then I get a lot of error messages about dropped frames - I'm not sure if ANY frames get encoded successfully. My CPU usage is very high as well. I get a 404 error from FMS when I enter the URL of the *.m3u8 file for one of the individual streams (the main livestream.m3u8 file is accessible though). I have also tried outputting to a file instead of FMS, with no success. All I get is some very garbled sound and no video.

  Any suggestions for what options/commands I should use to get this working ? Is anyone using ffmpeg with FMS to do HTTP Dynamic Streaming / HLS with MP4 video ? I've been struggling to get HDS/HLS working for some time now, and any help would be much appreciated ! It shouldn't make a difference, but I'm using FMS on Amazon EC2 with their AMI image.

  Thanks !