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• DXGI Desktop Duplication : encoding frames to send them over the network

  13 novembre 2016, par prazuber

  I’m trying to write an app which will capture a video stream of the screen and send it to a remote client. I’ve found out that the best way to capture a screen on Windows is to use DXGI Desktop Duplication API (available since Windows 8). Microsoft provides a neat sample which streams duplicated frames to screen. Now, I’ve been wondering what is the easiest, but still relatively fast way to encode those frames and send them over the network.

  The frames come from AcquireNextFrame with a surface that contains the desktop bitmap and metadata which contains dirty and move regions that were updated. From here, I have a couple of options :

  1. Extract a bitmap from a DirectX surface and then use an external library like ffmpeg to encode series of bitmaps to H.264 and send it over RTSP. While straightforward, I fear that this method will be too slow as it isn’t taking advantage of any native Windows methods. Converting D3D texture to a ffmpeg-compatible bitmap seems like unnecessary work.
  2. From this answer : convert D3D texture to IMFSample and use MediaFoundation’s SinkWriter to encode the frame. I found this tutorial of video encoding, but I haven’t yet found a way to immediately get the encoded frame and send it instead of dumping all of them to a video file.

  Since I haven’t done anything like this before, I’m asking if I’m moving in the right direction. In the end, I want to have a simple, preferably low latency desktop capture video stream, which I can view from a remote device.

  Also, I’m wondering if I can make use of dirty and move regions provided by Desktop Duplication. Instead of encoding the frame, I can send them over the network and do the processing on the client side, but this means that my client has to have DirectX 11.1 or higher available, which is impossible if I would want to stream to a mobile platform.

• avcodec : Remove libstagefright

  3 janvier 2016, par Derek Buitenhuis

  avcodec : Remove libstagefright
  It serves absolutely no purpose other than to confuse potentional
  
  Android developers about how to use hardware acceleration properly
  
  on the the platform. The stagefright "API" is not public, and the
  
  MediaCodec API is the proper way to do this.
  Furthermore, stagefright support in avcodec needs a series of
  
  magic incantations and version-specific stuff, such that
  
  using it actually provides downsides compared just using the actual
  
  Android frameworks properly, in that it is a lot more work and confusion
  
  to get it even running. It also leads to a lot of misinformation, like
  
  these sorts of comments (in [1]) that are absolutely incorrect.
  [1] http://stackoverflow.com/a/29362353/3115956
  Signed-off-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] Changelog
  • [DH] MAINTAINERS
  • [DH] configure
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/libstagefright.cpp
  • [DH] libavcodec/version.h
  • [DH] tools/build_libstagefright

• Swift Process Fails to Properly Send Metadata Args to FFMPEG

  30 avril 2019, par Ryan Stone

  I’m writing a Swift Process that concatenates a series of audio files using FFMPEG and libfdk_aac. The concatenation works, but when I pass metadata information through the process I get a Unrecognized option 'metadata artist="ff"' ... Option not found error.

  When debugging, if I use a breakpoint and print using e print(args.joined(separator: " ")) I’m able to take the exact output and paste it in the console, FFMPEG runs and doesn’t throw an error.

  I’m assuming there’s an oddity with how Swift process works, but even there I’ve tested and I’m stumped. I created a ruby script that took the args and looped over them and printed them and there is nothing given to the script that is unexpected. (Output below)

  Swift Process

  private func export() {
  
          guard let ffmpegPath = Bundle.main.path(forResource: "ffmpeg", ofType: "") else { return }
  
  
  
  
  
          var task = Process()
  
          task.launchPath = ffmpegPath
  
  
  
          let args: [String] = [
  
              "-i",
  
              #"concat:"\#(fileContents)""#,
  
              title(),
  
              artist(),
  
              narrator(),
  
              "-c:a",
  
              "libfdk_aac",
  
              "-vn",
  
              #"\#(exportPath)\#(exportFilename)"#
  
          ].compactMap { $0 }
  
  
  
          task.arguments = args
  
  
  
          var pipe = Pipe()
  
          setStdErrPipe(pipe: &pipe, task: &task)
  
          setTerminationNotification(task: task)
  
  
  
          task.launch()
  
      }
  
  
  
      func title() -> String? {
  
          guard metadata.titleText != "" else {
  
              return nil
  
          }
  
          return #"-metadata title="\#(metadata.titleText)""#
  
      }
  
  
  
      func artist() -> String? {
  
          guard metadata.authorText != "" else { return nil }
  
          return #"-metadata artist="\#(metadata.authorText)""#
  
      }
  
  
  
      func narrator() -> String? {
  
          guard metadata.narratorText != "" else { return nil }
  
          return #"-metadata album_artist="\#(metadata.narratorText)""#
  
      }

  Arg tester Output

  -i
  
  concat:"/Users/sharkmaul/Downloads/Bringing Up BÈbÈ/Bringing Up BÈbÈ-Part01.mp3|/Users/sharkmaul/Downloads/Bringing Up BÈbÈ/Bringing Up BÈbÈ-Part02.mp3"
  
  -metadata title="title"
  
  -metadata artist="author"
  
  -metadata album_artist="narrator"
  
  -c:a
  
  libfdk_aac
  
  -vn
  
  /Users/sharkmaul/Desktop/068F4F43-89EE-47F6-838D-7AD3E02E7F8A.m4a