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• Best approach to set up live video streaming between HoloLens2 and Desktop PC

  19 mai 2021, par SilverLife

  First of all, I am sorry for this question. I know its more asking for an advice than asking about any coding problems. Unfortunately I don´t know where else I should ask such a question, so please be patient. (I am open for any recommendations)

  


  Since a while I am searching for a promising approach to stream live videos from a desktop PC via network to my HoloLens 2 unity application. The video transfer should be within a encapsulated network without internet access. Therefore a direct connection between both devices without any signaling- or web-servers would be desirable, if possible. For now we are thinking about sending the stream via ffmpeg and receiving it somehow in the unity application.
So far I came across MixedReality-WebRTC and ffmpegInterop. Unfortunately as I read, WebRTC needs at least some kind of signaling server which manages the connection between the clients. ffmpegInterop seems to be really difficult to integrate into unity.

  


  I am completely new to the topic of low latency video streaming and a bit lost in this complex environment. Can anybody give me an advice about a promising and extendable way to receive a low latency video stream ?

  


• What version of ffmpeg is bundled inside electron ?

  7 août 2020, par greghmerrill

  The prebuilt electron binaries for Windows include the file ffmpeg.dll. How can I determine what version of the underlying ffmpeg library is actually compiled to produce this dll ? I need this information to understand what known vulnerabilities (CVE's, etc) might be in a given version of electron via ffmpeg.

  



  As I understand it, the ffmpeg dll itself is taken from https://github.com/electron/nightlies/releases/ when I download my dependencies (I'm using electron-prebuilt-compile). But I'm not getting a clear picture of what the source for that binary is. I think it might be from https://chromium.googlesource.com/chromium/third_party/ffmpeg/ but then I'm not clear on the relationship of that repo with the original ffmpeg repo (e.g. how often are fixes merged from the ffmpeg repo to the chromium third-party repo, etc.)

  



  I tried searching the content of the dll as per cody's suggestion, but no luck :

  



  $ strings ffmpeg.dll  | grep -i ffmp
FFmpeg video codec #1
Huffyuv FFmpeg variant
Not yet implemented in FFmpeg, patches welcome
C:\projects\libchromiumcontent\src\out-x64\static_library\ffmpeg.dll.pdb
ffmpeg.dll


$ strings ffmpeg.dll  | grep -i version
H.263 / H.263-1996, H.263+ / H.263-1998 / H.263 version 2
MPEG-4 part 2 Microsoft variant version 1
MPEG-4 part 2 Microsoft variant version 2
MPEG-4 part 2 Microsoft variant version 3
H.263+ / H.263-1998 / H.263 version 2
On2 VP6 (Flash version)
On2 VP6 (Flash version, with alpha channel)
old standard qpel (autodetected per FOURCC/version)
direct-qpel-blocksize bug (autodetected per FOURCC/version)
edge padding bug (autodetected per FOURCC/version)
strictly conform to a older more strict version of the spec or reference software
minor_version
premiere_version
quicktime_version
Assume this x264 version if no x264 version found in any SEI


  


• ffmpeg stream videos from two cams have a same device name

  21 novembre 2020, par junsang

  There are two cameras have a same device name Microsoft® LifeCam Studio(TM).
  
ffmpeg -list_deivces true -f dshow -i dummy prints the below output.

  



  C:\Users\user>ffmpeg -list_devices true -f dshow -i dummy
ffmpeg version git-2020-02-05-e6891d1 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 9.2.1 (GCC) 20200122
  configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libdav1d --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-libvo-amrwbenc --enable-libmysofa --enable-libspeex --enable-libxvid --enable-libaom --enable-libmfx --enable-ffnvcodec --enable-cuvid --enable-d3d11va --enable-nvenc --enable-nvdec --enable-dxva2 --enable-avisynth --enable-libopenmpt --enable-amf
  libavutil      56. 39.100 / 56. 39.100
  libavcodec     58. 67.101 / 58. 67.101
  libavformat    58. 37.100 / 58. 37.100
  libavdevice    58.  9.103 / 58.  9.103
  libavfilter     7. 74.100 /  7. 74.100
  libswscale      5.  6.100 /  5.  6.100
  libswresample   3.  6.100 /  3.  6.100
  libpostproc    55.  6.100 / 55.  6.100
[dshow @ 000001d5c5108dc0] DirectShow video devices (some may be both video and audio devices)
[dshow @ 000001d5c5108dc0]  "Microsoft┬« LifeCam Studio(TM)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_pnp_\\?\usb#vid_045e&pid_0811&mi_00#8&6ae46e6&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001d5c5108dc0]  "Microsoft┬« LifeCam Studio(TM)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_pnp_\\?\usb#vid_045e&pid_0811&mi_00#8&e544916&0&0000#{65e8773d-8f56-11d0-a3b9-00a0c9223196}\global"
[dshow @ 000001d5c5108dc0] DirectShow audio devices
[dshow @ 000001d5c5108dc0]  "Desktop Microphone (6- Microsoft┬« LifeCam Studio(TM))"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{D5F4881A-6E88-4563-8BA0-081CFD50E353}"
[dshow @ 000001d5c5108dc0]  "Desktop Microphone (5- Microsoft┬« LifeCam Studio(TM))"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{84674B28-DC68-4AC0-8331-D687C7B7D69C}"
[dshow @ 000001d5c5108dc0]  "Digital Audio (S/PDIF) (High Definition Audio Device)"
[dshow @ 000001d5c5108dc0]     Alternative name "@device_cm_{33D9A762-90C8-11D0-BD43-00A0C911CE86}\wave_{CDD24485-59D2-4BED-B6FC-B7447251C7E2}"


  



  Because the two cameras have a same device name, I couldn't stream two videos using this simple command at a same time : ffplay -f dshow -i video=Microsoft® LifeCam Studio(TM).
  
So I used pin names following the ffmpeg dshow example.
The only thing I could check was Could not find video device with name [video=~~pin name~~] among source devices of type video.

  



  What ffplay command makes enable to stream both videos ?