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• How to process video stream ?

  27 avril 2016, par sharpener

  I would like to ask some experienced multimedia professional how to proceed with following task :

  Given URL provides video stream and we would like to get access to decoded frames (byte stream in memory) in managed Win7+ application (C#). We don’t want to render/present the frames the standard way. The video format is known but not fixed (might get changed between two successive sessions, but we will know the parameters).

  So far, I have found there are several methods and I have build following picture in my mind :

  1. ffmpeg wrapper
     • Pros
       1. Self contained (no dependency to windows technologies)
       2. Powerful
     • Cons
       1. Little more complex to understand
       2. Lot of different wrapping variants (FFmpeg.NET, ffmpeg-sharp, ffmpeg-shard, FFmpeg.AutoGen, ...)
  2. DirectShow wrapper
     • Pros
       1. Widely used/supported technology (variaous filters freely available)
       2. Nice/detailed documentation on MSDN
     • Cons
       1. Quite old
       2. Considered obsolete from the point of author’s view (available only for desktop model on runtime >= Win8)
  3. MediaFoundation wrapper
     • Pros
       1. Theoretical successor of DirectShow, so should be available in the future
     • Cons
       1. Seems to be not as good as DirectShow
       2. Not very popular, limited "community" support
  4. FFmpegInterop wrapper
     • Pros
       1. Microsoft’s open source wrapper alternative
     • Cons
       1. Not available for runtime < Win8

• FFMPEG can't find audio device for webcam on one computer

  13 mars 2018, par David

  I am building a webcam recording app. I am using FFMPEG to capture the audio and video. I have a Logitech C930 webcam.

  >ffmpeg -list_devices true -f dshow -i dummy
  ffmpeg version N-90155-g28924f4b48 Copyright (c) 2000-2018 the FFmpeg developers
    built with gcc 7.3.0 (GCC)
    configuration : —enable-gpl —enable-version3 —enable-sdl2 —enable-bzlib —enable-fontconfig —enable-gnutls —enable-iconv —enable-libass —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-libmfx —enable-amf —enable-cuda —enable-cuvid —enable-d3d11va —enable-nvenc —enable-dxva2 —enable-avisynth
    libavutil      56.  7.101 / 56.  7.101
    libavcodec     58. 12.102 / 58. 12.102
    libavformat    58.  9.100 / 58.  9.100
    libavdevice    58.  2.100 / 58.  2.100
    libavfilter     7. 12.100 /  7. 12.100
    libswscale      5.  0.101 /  5.  0.101
    libswresample   3.  0.101 /  3.  0.101
    libpostproc    55.  0.100 / 55.  0.100
  [dshow @ 0000024786c38680] DirectShow video devices (some may be both video and audio devices)
  [dshow @ 0000024786c38680]  "Microsoft Camera Front"
  [dshow @ 0000024786c38680]     Alternative name "@device_pnp_~?\display#int3470#4&1835d135&0&uid13424#65e8773d-8f56-11d0-a3b9-00a0c9223196bf89b5a5-61f7-4127-a279-e187013d7caf"
  [dshow @ 0000024786c38680]  "Microsoft Camera Rear"
  [dshow @ 0000024786c38680]     Alternative name "@device_pnp_~?\display#int3470#4&1835d135&0&uid13424#65e8773d-8f56-11d0-a3b9-00a0c92231967c9bbcea-909c-47b3-8cf9-2aa8237e1d4b"
  [dshow @ 0000024786c38680]  "Logitech Webcam C930e"
  [dshow @ 0000024786c38680]     Alternative name "@device_pnp_~?\usb#vid_046d&pid_0843&mi_00#8&dd2d9e1&0&0000#65e8773d-8f56-11d0-a3b9-00a0c9223196\global"
  [dshow @ 0000024786c38680]  "ChromaCam"
  [dshow @ 0000024786c38680]     Alternative name "@device_sw_860BB310-5D01-11D0-BD3B-00A0C911CE863403512D-FE5D-4D68-B053-E86D662E4D58"
  [dshow @ 0000024786c38680] DirectShow audio devices
  [dshow @ 0000024786c38680]  "Microphone (2- Logitech Webcam C930e)"
  [dshow @ 0000024786c38680]     Alternative name "@device_cm_33D9A762-90C8-11D0-BD43-00A0C911CE86\wave_1AF7CBFB-477F-44D9-B8C4-E178F036B5D1"
  dummy : Immediate exit requested

  Notice the "Microphone (2- Logitech Webcam C930e)" audio device. I can capture from it using FFMPEG.

  Now, I move the same camera to a different computer (Intel Compute Stick) running nearly the same build of windows (16299.251 on the stick, 16299.248 on the laptop). Stick is 32-bit home and laptop is 64-bit Pro (shouldn’t matter, should it ?).
  I run the same command with the exact same camera and same drivers installed :

  >ffmpeg -list_devices true -f dshow -i dummy
  ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
    built with gcc 7.3.0 (GCC)
    configuration : —enable-gpl —enable-version3 —enable-sdl2 —enable-bzlib —enable-fontconfig —enable-gnutls —enable-iconv —enable-libass —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-libmfx —enable-cuda —enable-cuvid —enable-d3d11va —enable-nvenc —enable-dxva2 —enable-avisynth
    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
    libswscale      4.  8.100 /  4.  8.100
    libswresample   2.  9.100 /  2.  9.100
    libpostproc    54.  7.100 / 54.  7.100
  [dshow @ 00797be0] DirectShow video devices (some may be both video and audio devices)
  [dshow @ 00797be0]  "Logitech Webcam C930e"
  [dshow @ 00797be0]     Alternative name "@device_pnp_~?\usb#vid_046d&pid_0843&mi_00#6&dd2d9e1&0&0000#65e8773d-8f56-11d0-a3b9-00a0c9223196\global"
  [dshow @ 00797be0] DirectShow audio devices
  [dshow @ 00797be0] Could not enumerate audio only devices (or none found).
  dummy : Immediate exit requested
  

  No Audio device listed ? What ? If I use python’s sounddevice module, it sees the audio device :

  > python -m sounddevice
  0 Microsoft Sound Mapper - Output, MME (0 in, 2 out)
   1 Remote Audio, MME (0 in, 2 out)
    2 Primary Sound Driver, Windows DirectSound (0 in, 2 out)
    3 Remote Audio, Windows DirectSound (0 in, 2 out)
    4 Remote Audio, Windows WASAPI (0 in, 2 out)
    5 Microphone (Logitech Webcam C930e), Windows WDM-KS (2 in, 0 out)
  

  I can capture from that audio device with sounddevice, but I can’t get FFMPEG to capture from it.

  >ffmpeg -report -rtbufsize 50000k-f dshow -i video="Logitech Webcam C930e":audio="Microphone (Logitech Webcam C930e)" -t 120 -y -s 1920x1080 -q 2 -video_pin_name 1 -audio_pin_name 5 -filter:v setpts=1*PTS Watchmen_20180312095119_c.avi
  ffmpeg started on 2018-03-12 at 17:07:08
  Report written to "ffmpeg-20180312-170708.log"
  ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
    built with gcc 7.3.0 (GCC)
    configuration : —enable-gpl —enable-version3 —enable-sdl2 —enable-bzlib —enable-fontconfig —enable-gnutls —enable-iconv —enable-libass —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-libmfx —enable-cuda —enable-cuvid —enable-d3d11va —enable-nvenc —enable-dxva2 —enable-avisynth
    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
    libswscale      4.  8.100 /  4.  8.100
    libswresample   2.  9.100 /  2.  9.100
    libpostproc    54.  7.100 / 54.  7.100
  video=Logitech Webcam C930e:audio=Microphone (Logitech Webcam C930e) : No such file or directory
  

  I have been trying to debug by removing and reinstalling drivers, etc, but to no avail. I also grabbed a Microsoft Lifecam webcam and got similar results. I can see the lifecam’s audio on the laptop but not the stick in just the same manner as the logitech camera.
  How can I get the audio device to show up on the stick so I can capture from it ?

• Why Can't i view a few of my mp4 files in my .erb but can in html file ?

  27 avril 2016, par Joseph McKenzie

  I have a site that I’m working on for a customer and the strangest thing is happening to me. I pull in a list of videos from a database table and it plays the video that I want it to, this all works fine.

  For some reason some of the video files will not play in either chrome nor Firefox when viewing my page from an .erb file,but they will work in Microsoft edge. They will all work in an .html file though in all my browsers they are raw .264 files converted to mp4 via ffmpeg .

  I would think if it was a file corruption it wouldn’t play fine in a .html file or Edge.

  <% links[0,1].each do |links|%>-->
  
  
  
  <% if  links[1] == "Not_Watched"%>
  
  
  
  <video width="320" height="240" controls="controls">
  
  <source src="../videos/&lt;%=links[0]%>" type="video/mp4">
  
  
  
  </source></video>
  
  &lt;%end%>
  
  &lt;%end%>
  
  
  
   get '/page1' do
  
  
  
  
  
  thing1= database.execute("select * from thing1");
  
  thing2= database.execute("select * from thing2")                
  
  links = database.execute("select * from links")                 
  
  
  
  
  
  
  
     erb :page1, :locals => {:thing1=> thing1, :thing2=> thing2, :links => links}
  
  
  
  
  
  
  
   end

  I had to change some of the code names up because i cant put up to much of this code online...... and there is a lot more I didn’t include because didn’t have anything to do with anything as far as I could imagine. If anyone thinks it could have a bearing ill post some of it but changed up so that I can