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• FFMPEG Encoding MP4 for iOS

  3 août 2015, par Ryan K

  I am using the gem streamio-ffmpeg to convert an .mp4 file to another .mp4 file that conforms to iOS standards. I want to put that file in an HTML5 video tag. The video plays well on desktop and Android devices. However, no matter what I do, the iPad Mini 2 that I’m using will not play the video.

  My options hash looks like this :

  options = {video_codec: "libx264", resolution: "480x320", frame_rate: 30, video_bitrate: 500,
  
               x264_vprofile: "baseline", x264_preset: "slow", audio_codec: "aac", audio_bitrate: 56, aspect: 1.333333,
  
               audio_sample_rate: 44100, audio_channels: 1, custom: "-strict -2"}

  When I load the new .mp4 file back into streamio-ffmpeg, this is the object (and metadata) returned :

  #

  I’ve tried just about everything I could find, with different bit rates, codecs, resolutions, etc. What are the correct options to play an .mp4 on an iOS device ?

  BTW, streamio-ffmpeg allows pure ffmpeg options, so I’m ok with that.

• 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.

• Simulating MPEG1/2 transmission over a noisy channel [on hold]

  17 novembre 2015, par StepTNT

  The question may sound out of scope here but this is my last resource.

  I need to write a software that does :

  1. Get an uncompressed video from disk
  2. Compress it into MPEG-1 or MPEG-2 being able to change quantization matrix, GOP size and/or macroblock size for DCT/motion search
  3. Apply a repetition code to add redundancy
  4. Simulate transmission over a noisy channel with given error rate
  5. Reconstruct the original stream from the repetition code
  6. Decode the video and compare it with the original one by gathering stats like frame-by-frame difference, file size and stuff like that

  This should by done by a nice GUI to show the input and output videos, alongside their frame difference.

  Given what I need to do, I can write some requirements :

  • An encoder which allows me to change some of the parameters (needed for point 2)
  • A language that allows me to work at bit level (needed for points 3 and 5)
  • A language that allows me to build a nice GUI using a designer (GUI is not the core of the project so I can’t afford wasting time by writing one)

  So far my searches have led to mixed results that are not giving me enough resources to start.

  My first find was this MATLAB project which implements MPEG and has some parameters that can be tweaked (like quantization matrix and GOP pattern for example).
  The problem here is that I don’t know MATLAB at all, so I have no idea on how to link everything and build a GUI.

  So the next step was to move to JAVA, and I found a LOT of FFMPEG wrappers, but none seems to allow me to set the parameters that I need. My last try was with Xuggler but the Wiki is down and the documentation does not talk about what I need. Plus, JAVA doesn’t work at bit level so I’d have issues applying the repetition code.

  Failing with JAVA led me to C# and DirectShowNet, but the documentation is quite lacking and I don’t know how to start because I didn’t find anything related to setting the parameters that I need using Filters.

  The question now is : is there any language/framework/platform that allows me to do what I need without having to deal with pure C/C++ ?
  I’d expect a lot of stuff on this matter since we’re talking about well known codecs, still I’m having a hard time finding what I need.