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• Registration free (sxs) COM DirectShow filter

  21 septembre 2015, par caesay

  There are questions asking on how to get Registration free COM working, and this is not one of those. I have a DirectShow video source filter (catagory 860BB310-5D01-11d0-BD3B-00A0C911CE86) implemented in .Net with the help of an edited version of the code available here : Pure .Net DirectShow Filters by Maxim Kartavenkov.

  I need to get ffmpeg to recognize my .Net DirectShow filter as a video source using Registration Free COM (Side by Side / sxs). Built into the .Net framework is support for COM component servers, so theoretically as long as the manifests are correct, ffmpeg should detect the filters.

  Here is a snippet of the relevant sections of my manifest files currently.

  <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
  
  <assembly manifestversion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
  
  <assemblyidentity version="1.0.0.0" type="win32" processorarchitecture="*"></assemblyidentity>
  
  <dependency>
  
   <dependentassembly>
  
    <assemblyidentity version="1.0.0.0" publickeytoken="26A05D7C90FBA3E8"></assemblyidentity>
  
   </dependentassembly>
  
  </dependency>
  
  </assembly>

  <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
  
  <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestversion="1.0">
  
     <assemblyidentity version="1.0.0.0" publickeytoken="26A05D7C90FBA3E8"></assemblyidentity>
  
     <clrclass clsid="{65722BE6-3449-4628-ABD3-74B6864F9739}" progid="DShowVideoFilter.VideoCaptureFilter" threadingmodel="Both" runtimeversion="v2.0.50727"></clrclass>
  
     <file>
  
     </file>
  
     <file>
  
       <typelib tlbid="{B618E67B-64C8-48E9-9F94-F13214B76808}" version="1.0" helpdir="" flags="hasdiskimage"></typelib>
  
     </file>
  
  </assembly>

  So, I get no errors when running ffmpeg (like you would if there was a manifest error) - and I am confident that everything that is configured correctly (related to traditional sxs com loading), the problem I think (unconfirmed) is that ffmpeg loads DShow filters via DirectShow’s intelligent connect system, which requires the filter and pins to be registered. Here are some documents that talk about how filters need to be registered that I’ve found :

  • #1 Registering DirectShow Filters
  • #2 Implementing DllRegisterServer

  Now, in Maxim Kartavenkov’s DShow base classes, he takes care of #2 automatically. Here is a significantly shortened version of the method that registers the filters implementing BaseFilter.

  [ComRegisterFunction]
  
  public static void RegisterFunction(Type _type)
  
  {
  
      AMovieSetup _setup = (AMovieSetup)Attribute.GetCustomAttribute(_type, typeof(AMovieSetup));
  
      BaseFilter _filter = (BaseFilter)Activator.CreateInstance(_type);
  
      string _name = _filter.Name;
  
      DsGuid _category = new DsGuid(_setup.Category);
  
      IFilterMapper2 _mapper2 = (IFilterMapper2)new FilterMapper2();
  
  
  
      RegFilter2 _reg2 = new RegFilter2();
  
      _reg2.dwVersion = (int)_setup.Version;
  
      _reg2.dwMerit = _setup.FilterMerit;
  
      _reg2.rgPins = IntPtr.Zero;
  
      _reg2.cPins = 0;
  
  
  
      IntPtr _register = Marshal.AllocCoTaskMem(Marshal.SizeOf(_reg2));
  
      Marshal.StructureToPtr(_reg2, _register, true);
  
  
  
      hr = _mapper2.RegisterFilter(_type.GUID, _name, IntPtr.Zero, _category, _instance, _register);
  
  
  
      Marshal.FreeCoTaskMem(_register);
  
  }

  That is the method (particularly mapper2.RegisterFilter) that allows ffmpeg to find the DShow filter when it is registered traditionally (with RegAsm) into the registry, which creates registry keys for the filter and pins as described by #2 link.

  tldr ;
  So the question is, how to emulate the function of RegisterFilter or the intelligent connect registry entries this within a manifest file as to allow the sxs context to find my DirectShow filter when ffmpeg searches for it.

• Raspberry Pi HLS streaming [on hold]

  5 mars 2015, par Razvan-Catalin Olaru

  I have a rev. B Raspberry Pi and want to stream from my Microsoft Lifecam VX-800 to a web server using HLS protocol and avconv/ffmpeg, preferably without using raspivid because it’s not working (couldn’t figure out why). The stream needs to be fed to jwplayer. I went through a lot of guides but none seem to be fitting my needs. Could you give me detailed instructions on how to do the live streaming or give me links to detailed tutorials that you tried and worked ?

  Thanks.

• How to generate pcm audio file by setting 20 bit depth ?

  6 juillet 2015, par vip007

  No option using ffmpeg

  I am using ffmpeg to generate audio data. I am using following command

  ffmpeg.exe -i in.wav -ar 44100  -acodec pcm_s16le  -ac 1 out.wav

  but there is no option to convert to 20 bit depth pcm audio. (something like pcm_s20le).

  I want to perform some operations on apple codec (e.g. encoding pcm audio data to alac).

  On ALAC source : http://alac.macosforge.org/trac/browser/trunk/ReadMe.txt , it has been mentioned like this ;

  Apple Lossless supports the following features
  1. Bit depths 16, 20, 24 and 32 bits.

  Media Foundation on windows throwing exception for 20 bit depth

  I tried sample encoding and transcoding application mentioned on MSDN https://code.msdn.microsoft.com/windowsapps/media-transcode-sample-f7ba5269

  with following configuration but it failed

  spTypeOut->SetUINT32(MF_MT_AUDIO_BITS_PER_SAMPLE, 20);  

  NOTE : but i put 16 instead of 20 ; it created smoothly.

  Is there any way to generate such 20 bit PCM audio ? What is so special about 20 bit depth that it is not being considered on ffmpeg and media foundation but on apple codec ?