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• Rails 5 - Video streaming using Carrierwave uploaded video size constraint on the server

  21 mars 2020, par Milind

  I have a working Rails 5 apps using Reactjs for frontend and React dropzone uploader to upload video files using carrierwave.

  So far, what is working great is listed below -

  1. User can upload videos and videos are encoded based on the selection made by user - HLS or MPEG-DASH for online streaming.
  2. Once the video is uploaded on the server, it starts streaming it by :-
     • FIRST,copying video on /tmp folder.
     • Running a bash script that uses ffmpeg to transcode uploaded video using predefined commands to produce new fragments of videos inside /tmp folder.
     • Once the background job is done, all the videos are uploaded on AWS S3, which is how the default carrierwave works
  3. So, when multiple videos are uploaded, they are all copied in /tmp folder and then transcoded and eventually uploaded to S3.

  My questions, where i am looking some help are listed below -

  1- The above process is good for small videos, BUT what if there are many concurrent users uploading 2GB of videos ? I know this will kill my server as my /tmp folder will keep on increasing and consume all the memory, making it to die hard.How can I allow concurrent videos to upload videos without effecting my server’s memory consumption ?

  2- Is there a way where I can directly upload the videos on AWS-S3 first, and then use one more proxy server/child application to encode videos from S3, download it to the child server, convert it and again upload it to the destination ? but this is almost the same but doing it on cloud, where memory consumption can be on-demand but will be not cost-effective.

  3- Is there some easy and cost-effective way by which I can upload large videos, transcode them and upload it to AWS S3, without effecting my server memory. Am i missing some technical architecture here.

  4- How Youtube/Netflix works, I know they do the same thing in a smart way but can someone help me to improve this ?

  Thanks in advance.

• Consume FFmpeg XCFramework from Objective-C, headers not found

  19 novembre 2020, par jamone

  I built FFmpeg for Apple's platforms as an XCFramework. I used the script in https://github.com/kewlbear/FFmpeg-iOS-build-script/pull/147 to do so.

  



  I'm trying to now consume that framework inside a traditional iOS/macOS framework (named VideoEditing), that then is used inside my iOS app (soon to try and be Catalyst).

  



  In VideoEditing I have linked to FFmpeg.xcframework and then in the app that uses VideoEditing I have linked & embedded FFmpeg.xcframework. Previously I was building FFmpeg as a standard static library, and using that from inside VideoEditing in a Objective-C++ wrapper so I can use it all from Swift.

  



  In that Objective-C++ file I would import FFmpeg headers like #import <libswscale></libswscale>swscale.h> To make that work, I had to set header search paths. How are you supposed to do it once you convert to the XCFramework ? I've tried @import FFmpeg, #import <ffmpeg></ffmpeg>libswscale/swscale.h>, #import <ffmpeg></ffmpeg>swscale.h> as well as #import <libswscale></libswscale>swscale.h>. In every case I just get a file not found error on the import line.

  



  All of Apple's examples are showing it just in Swift with the framework vending a module. If I was to try and still set a header search path, you now have different headers per architecture.

  



  

  


• How to create a virtual webcamera device with ability to stream a video file in linux

  27 février 2020, par Vlad

  I need to create a script, that will stream a video file to virtual webcam, and make a virtual webcam accessible not only with ffplay /dev/videoX etc. but also with different applications like Cheese(default Ubuntu webcam app), Chrome, Discord and others.
  I tried solutions that use v4l2loopback and ffmpeg, but this doesn’t work in Chrome/Discord/Cheese/...
  Now I have several webcams :

  1. /dev/video0 - Native laptop camera
  2. /dev/video1 - A camera created with DroidCamX to use phones camera
     as laptop camera
  3. /dev/video2 - v4l2loopback camera

  When I try to stream a video file to /dev/video2 with ffmpeg, this message is showing up :

  user@hostname:~/Videos$ sudo ffmpeg -re -i "video.mp4" -map 0:0 -f v4l2 /dev/video2
  
  ffmpeg version 3.4.6-0ubuntu0.18.04.1 Copyright (c) 2000-2019 the FFmpeg developers
  
    built with gcc 7 (Ubuntu 7.3.0-16ubuntu3)
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.18.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-librsvg --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  
    libavutil      55. 78.100 / 55. 78.100
  
    libavcodec     57.107.100 / 57.107.100
  
    libavformat    57. 83.100 / 57. 83.100
  
    libavdevice    57. 10.100 / 57. 10.100
  
    libavfilter     6.107.100 /  6.107.100
  
    libavresample   3.  7.  0 /  3.  7.  0
  
    libswscale      4.  8.100 /  4.  8.100
  
    libswresample   2.  9.100 /  2.  9.100
  
    libpostproc    54.  7.100 / 54.  7.100
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'video.mp4':
  
    Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.83.100
  
    Duration: 02:09:13.10, start: 0.000000, bitrate: 279 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 798x598 [SAR 1:1 DAR 399:299], 146 kb/s, 24 fps, 24 tbr, 12288 tbn, 48 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: mp3 (mp4a / 0x6134706D), 48000 Hz, stereo, s16p, 128 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> rawvideo (native))
  
  Press [q] to stop, [?] for help
  
  [v4l2 @ 0x5609f238c280] ioctl(VIDIOC_G_FMT): Invalid argument
  
  Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument
  
  Error initializing output  stream 0:0
  
  Conversion failed!

  But when I run that command with /dev/video0, a stream starts and shows with ffplay /dev/video0. But applications, except Mozilla Firefox cannot detect /dev/video0 stream.
  So how can I create a virtual camera device properly in order to stream a video file to it and use as a camera in various applications ?

  I have Linux Ubuntu 18.04.4 LTS, kernel version : 5.3.0-40-generic, architecture : x86-64.
  Any help appreciated !