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• ffmpeg in C# (ScrCpy)

  23 janvier 2020, par RunicSheep

  I’m trying to access the screen of my android device like ScrCpy does (https://github.com/Genymobile/scrcpy) but in C#.
  What I’ve done so far is pushing the jar (server) to my device and receiving the input. (Device resolution etc.)
  But I can’t re implement the decoding process in c#, there has to be some sort of error so far.
  C# library used for ffmpeg is ffmpeg.AutoGen (https://github.com/Ruslan-B/FFmpeg.AutoGen)

  Here’s the decoding code :

      using System;
  
  using System.Drawing;
  
  using System.Drawing.Imaging;
  
  using System.IO;
  
  using System.Linq;
  
  using System.Net;
  
  using System.Net.Sockets;
  
  using System.Runtime.InteropServices;
  
  using System.Runtime.InteropServices.ComTypes;
  
  using System.Threading;
  
  using FFmpeg.AutoGen;
  
  
  
  namespace Source.Android.Scrcpy
  
  {
  
      public unsafe class Decoder
  
      {
  
          private const string LD_LIBRARY_PATH = "LD_LIBRARY_PATH";
  
  
  
          private AVFrame* _decodingFrame;
  
          private AVCodec* _codec;
  
          private AVCodecContext* _codec_ctx;
  
          private AVFormatContext* _format_ctx;
  
  
  
          public Decoder()
  
          {
  
              RegisterFFmpegBinaries();
  
              SetupLogging();
  
  
  
              this.InitFormatContext();
  
          }
  
  
  
          private void InitFormatContext()
  
          {
  
              _decodingFrame = ffmpeg.av_frame_alloc();
  
              _codec = ffmpeg.avcodec_find_decoder(AVCodecID.AV_CODEC_ID_H264);
  
              if (_codec== null)
  
              {
  
                  throw new Exception("H.264 decoder not found");// run_end;
  
              }
  
  
  
              _codec_ctx = ffmpeg.avcodec_alloc_context3(_codec);
  
              if (_codec_ctx == null)
  
              {
  
                  throw new Exception("Could not allocate decoder context"); //run_end
  
              }
  
  
  
              if (ffmpeg.avcodec_open2(_codec_ctx, _codec, null) < 0)
  
              {
  
                  throw new Exception("Could not open H.264 codec");// run_finally_free_codec_ctx
  
              }
  
  
  
              _format_ctx = ffmpeg.avformat_alloc_context();
  
              if (_format_ctx == null)
  
              {
  
                  throw new Exception("Could not allocate format context");// run_finally_close_codec;
  
              }
  
          }
  
  
  
          private void RegisterFFmpegBinaries()
  
          {
  
              switch (Environment.OSVersion.Platform)
  
              {
  
                  case PlatformID.Win32NT:
  
                  case PlatformID.Win32S:
  
                  case PlatformID.Win32Windows:
  
                      var current = Environment.CurrentDirectory;
  
                      var probe = Path.Combine("FFmpeg", Environment.Is64BitProcess ? "x64" : "x86");
  
                      while (current != null)
  
                      {
  
                          var ffmpegDirectory = Path.Combine(current, probe);
  
                          if (Directory.Exists(ffmpegDirectory))
  
                          {
  
                              Console.WriteLine($"FFmpeg binaries found in: {ffmpegDirectory}");
  
                              RegisterLibrariesSearchPath(ffmpegDirectory);
  
                              return;
  
                          }
  
                          current = Directory.GetParent(current)?.FullName;
  
                      }
  
                      break;
  
                  case PlatformID.Unix:
  
                  case PlatformID.MacOSX:
  
                      var libraryPath = Environment.GetEnvironmentVariable(LD_LIBRARY_PATH);
  
                      RegisterLibrariesSearchPath(libraryPath);
  
                      break;
  
              }
  
          }
  
          private static void RegisterLibrariesSearchPath(string path)
  
          {
  
              switch (Environment.OSVersion.Platform)
  
              {
  
                  case PlatformID.Win32NT:
  
                  case PlatformID.Win32S:
  
                  case PlatformID.Win32Windows:
  
                      SetDllDirectory(path);
  
                      break;
  
                  case PlatformID.Unix:
  
                  case PlatformID.MacOSX:
  
                      string currentValue = Environment.GetEnvironmentVariable(LD_LIBRARY_PATH);
  
                      if (string.IsNullOrWhiteSpace(currentValue) == false && currentValue.Contains(path) == false)
  
                      {
  
                          string newValue = currentValue + Path.PathSeparator + path;
  
                          Environment.SetEnvironmentVariable(LD_LIBRARY_PATH, newValue);
  
                      }
  
                      break;
  
              }
  
          }
  
  
  
          [DllImport("kernel32", SetLastError = true)]
  
          private static extern bool SetDllDirectory(string lpPathName);
  
  
  
          private AVPacket GetPacket()
  
          {
  
              var packet = ffmpeg.av_packet_alloc();
  
              ffmpeg.av_init_packet(packet);
  
  
  
              packet->data = null;
  
              packet->size = 0;
  
  
  
              return *packet;
  
          }
  
  
  
          private static int read_raw_packet(void* opaque, ushort* buffer, int bufSize)
  
          {
  
              var buffSize = 1024;
  
              var remaining = dt.Length - dtp - 1;
  
              var written = 0;
  
              for (var i = 0; i < buffSize && i+dtp < dt.Length; i++)
  
              {
  
                  buffer[i] = dt[i+dtp];
  
                  written++;
  
              }
  
  
  
              dtp += written;
  
  
  
              if (written <= 0)
  
              {
  
                  return ffmpeg.AVERROR_EOF;
  
              }
  
  
  
              return written;
  
          }
  
  
  
          [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
  
          public delegate int av_read_function_callback(void* opaque, ushort* endData, int bufSize);
  
  
  
          private static byte[] dt;
  
          private static int dtp;
  
  
  
          public Bitmap DecodeScrCpy(byte[] data)
  
          {
  
              if (data.Length == 0)
  
              {
  
                  return null;
  
              }
  
  
  
              byte* _buffer;
  
              ulong _bufferSize = 1024*2;
  
              _buffer = (byte*)ffmpeg.av_malloc(_bufferSize);
  
              if (_buffer == null)
  
              {
  
                  throw new Exception("Could not allocate buffer"); // run_finally_free_format_ctx;
  
              }
  
  
  
              fixed (byte* dataPtr = data)
  
              {
  
                  dt = data;
  
                  dtp = 0;
  
                  fixed (AVFormatContext** formatCtxPtr = &_format_ctx)
  
                  {
  
                      var mReadCallbackFunc = new av_read_function_callback(read_raw_packet);
  
                      AVIOContext* avio_ctx = ffmpeg.avio_alloc_context(_buffer, (int)_bufferSize, 0, null, //TODO: IntPtr.Zero nutzen?
  
                          new avio_alloc_context_read_packet_func{Pointer = Marshal.GetFunctionPointerForDelegate(mReadCallbackFunc) }, 
  
                          null, null);
  
                      if (avio_ctx == null)
  
                      {
  
                          ffmpeg.av_free(dataPtr);
  
                          throw new Exception("Could not allocate avio context"); //goto run_finally_free_format_ctx;
  
                      }
  
  
  
                      _format_ctx->pb = avio_ctx;
  
  
  
                      if (ffmpeg.avformat_open_input(formatCtxPtr, null, null, null) < 0)
  
                      {
  
                          throw new Exception("Could not open video stream"); // goto run_finally_free_avio_ctx;
  
                      }
  
  
  
                      var packet = GetPacket();
  
  
  
                      while (ffmpeg.av_read_frame(_format_ctx, &packet) == 0)
  
                      {
  
                          if (ffmpeg.LIBAVDEVICE_VERSION_INT >= ffmpeg.AV_VERSION_INT(57, 37, 0))
  
                          {
  
                              int ret;
  
                              if ((ret = ffmpeg.avcodec_send_packet(_codec_ctx, &packet)) < 0)
  
                              {
  
                                  throw new Exception($"Could not send video packet: {ret}"); //goto run_quit
  
                              }
  
  
  
                              ret = ffmpeg.avcodec_receive_frame(_codec_ctx, _decodingFrame);
  
                              if (ret == 0)
  
                              {
  
                                  // a frame was received
  
                              }
  
                              else if (ret != ffmpeg.AVERROR(ffmpeg.EAGAIN))
  
                              {
  
                                  ffmpeg.av_packet_unref(&packet);
  
                                  throw new Exception($"Could not receive video frame: {ret}"); //goto run_quit;
  
                              }
  
                          }
  
                      }
  
                  }
  
              }
  
  
  
              return null;
  
          }
  
      }
  
  }

  Entry is DecodeScrCpy with read data from network stream.
  Things I noticed :

  • read_raw_packet is called again after ffmpeg.AVERROR_EOF is returned
  • ffmpeg.avformat_open_input fails

  Question is, did I miss anything ?

• why am i getting very low encoding bitrate using vaapi in ffmpeg

  19 janvier 2021, par ohroblot

  I am using this command :

  


  ffmpeg -y \
-vaapi_device /dev/dri/renderD128 \
-loop 1 -r 1 -i ./image.jpg -pix_fmt vaapi_vld \                                          
-b:v 18000k -minrate 18000k \
-vf 'format=nv12|vaapi,hwupload,scale_vaapi=w=1280:h=720' \ 
-rc_mode 3 \
-r 30 -g 60 \
-c:v h264_vaapi -f flv /dev/null


  


  I am getting very low bitrate with this, the bitrate is as low as 100Kbits/s. I get faster encoding using libx264 and my cpu. Is it an underpowered GPU ? am I missing some ffmpeg arguments ?

  


  I am not sure what's going on, could this be an issue with linux, mesa drivers, did i miss some options when I compiled ffmpeg ?

  


  vainfo

  


  error: can't connect to X server!
libva info: VA-API version 1.8.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/radeonsi_drv_video.so
libva info: Found init function __vaDriverInit_1_8
libva info: va_openDriver() returns 0
vainfo: VA-API version: 1.8 (libva 2.8.0)
vainfo: Driver version: Mesa Gallium driver 20.2.6 for AMD Radeon (TM) RX 480 Graphics (POLARIS10, DRM 3.38.0, 5.8.0-7630-generic, LLVM 11.0.0)
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            : VAEntrypointVLD
      VAProfileMPEG2Main              : VAEntrypointVLD
      VAProfileVC1Simple              : VAEntrypointVLD
      VAProfileVC1Main                : VAEntrypointVLD
      VAProfileVC1Advanced            : VAEntrypointVLD
      VAProfileH264ConstrainedBaseline: VAEntrypointVLD
      VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
      VAProfileH264Main               : VAEntrypointVLD
      VAProfileH264Main               : VAEntrypointEncSlice
      VAProfileH264High               : VAEntrypointVLD
      VAProfileH264High               : VAEntrypointEncSlice
      VAProfileHEVCMain               : VAEntrypointVLD
      VAProfileHEVCMain               : VAEntrypointEncSlice
      VAProfileHEVCMain10             : VAEntrypointVLD
      VAProfileJPEGBaseline           : VAEntrypointVLD
      VAProfileNone                   : VAEntrypointVideoProc


  


  ffmpeg -buildconf

  


  ffmpeg version N-100671-gc48110a4a4 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 10 (Ubuntu 10.2.0-13ubuntu1)
  configuration: --prefix=/home/_user/Dev/ffmpeg_build/build --extra-cflags='-I/home/_user/Dev/ffmpeg_build/build/include -I/usr/include' --extra-ldflags='-L/home/_user/Dev/ffmpeg_build/build/lib -L/home/_user/Dev/ffmpeg_build/build/lib/x86_64-linux-gnu -Wl,-rpath=/home/_user/Dev/ffmpeg_build/build/lib/x86_64-linux-gnu -ldrm -L/usr/lib' --pkg-config-flags=--static --extra-libs='-lpthread -lm' --bindir=/home/_user/Dev/ffmpeg_build/bin --arch=amd64 --disable-shared --disable-ffprobe --disable-ffplay --disable-gnutls --enable-openssl --enable-zlib --enable-librtmp --enable-static --enable-chromaprint --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree --enable-vdpau --enable-ladspa --enable-libaom --enable-libbs2b --enable-libcaca --enable-libcodec2 --enable-libdav1d --enable-libfontconfig --enable-libfribidi --enable-libgme --enable-libopenjpeg --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libwebp --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-libass --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-librabbitmq --enable-libvorbis --enable-libvpx --enable-libflite --enable-chromaprint --enable-frei0r
  libavutil      56. 63.101 / 56. 63.101
  libavcodec     58.117.101 / 58.117.101
  libavformat    58. 65.101 / 58. 65.101
  libavdevice    58. 11.103 / 58. 11.103
  libavfilter     7. 96.100 /  7. 96.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100

  configuration:
    --prefix=/home/_user/Dev/ffmpeg_build/build
    --extra-cflags='-I/home/_user/Dev/ffmpeg_build/build/include -I/usr/include'
    --extra-ldflags='-L/home/_user/Dev/ffmpeg_build/build/lib -L/home/_user/Dev/ffmpeg_build/build/lib/x86_64-linux-gnu -Wl,-rpath=/home/_user/Dev/ffmpeg_build/build/lib/x86_64-linux-gnu -ldrm -L/usr/lib'
    --pkg-config-flags=--static
    --extra-libs='-lpthread -lm'
    --bindir=/home/_user/Dev/ffmpeg_build/bin
    --arch=amd64
    --disable-shared
    --disable-ffprobe
    --disable-ffplay
    --disable-gnutls
    --enable-openssl
    --enable-zlib
    --enable-librtmp
    --enable-static
    --enable-chromaprint
    --enable-gpl
    --enable-libass
    --enable-libfdk-aac
    --enable-libfreetype
    --enable-libmp3lame
    --enable-libopus
    --enable-libvorbis
    --enable-libvpx
    --enable-libx264
    --enable-libx265
    --enable-nonfree
    --enable-vdpau
    --enable-ladspa
    --enable-libaom
    --enable-libbs2b
    --enable-libcaca
    --enable-libcodec2
    --enable-libdav1d
    --enable-libfontconfig
    --enable-libfribidi
    --enable-libgme
    --enable-libopenjpeg
    --enable-librsvg
    --enable-librubberband
    --enable-libshine
    --enable-libsnappy
    --enable-libsoxr
    --enable-libspeex
    --enable-libsrt
    --enable-libssh
    --enable-libtheora
    --enable-libtwolame
    --enable-libvidstab
    --enable-libwebp
    --enable-libxml2
    --enable-libxvid
    --enable-libzmq
    --enable-libzvbi
    --enable-lv2
    --enable-omx
    --enable-openal
    --enable-opencl
    --enable-opengl
    --enable-sdl2
    --enable-pocketsphinx
    --enable-libdc1394
    --enable-libdrm
    --enable-libiec61883
    --enable-libass
    --enable-libfreetype
    --enable-libgsm
    --enable-libmp3lame
    --enable-libmysofa
    --enable-libopenjpeg
    --enable-libopenmpt
    --enable-libopus
    --enable-librabbitmq
    --enable-libvorbis
    --enable-libvpx
    --enable-libflite
    --enable-chromaprint
    --enable-frei0r


  


  a link to full logs : http://0x0.st/-i2j.txt

  


• Interfacing to an Xbox Optical Drive

  1er octobre 2013, par Multimedia Mike — xbox

  The next generation Xbox is going to hit the streets soon. But for some reason, I’m still interested in the previous generation’s unit (i.e., the original Xbox). Specifically, I’ve always wondered if it’s possible to use the original Xbox’s optical drive in order to read Xbox discs from Linux. I was never curious enough to actually buy an Xbox just to find out but I eventually came across a cast-off console on a recycle pile.

  I have long known that the Xbox has what appears to be a more or less standard optical drive with a 40-pin IDE connector. The only difference is the power adapter which I surmise is probably the easiest way to turn a bit of standardized hardware into a bit of proprietary hardware. The IDE and power connectors look like this :

  
  
  

  Thus, I wanted to try opening an Xbox and plugging the optical drive into a regular PC, albeit one that supports IDE cables, and allow the Xbox to supply power to the drive. Do you still have hardware laying around that has 40-pin IDE connectors ? I guess my Mac Mini PPC fits the bill, but I’ll be darned if I’m going to pry that thing open again. I have another IDE-capable machine buried in my closet, last called into service when I needed a computer with a native RS-232 port 3 years ago. The ordeal surrounding making this old computer useful right now can be another post entirely.

  Here’s what the monstrosity looks like thanks to characteristically short IDE cable lengths :

  
  

  

  Click for larger image

  
  

  Process :

  1. Turn on Xbox first
  2. Turn on PC

  Doing these things in the opposite order won’t work since the kernel really wants to see the drive when booting up. Inspecting the 'dmesg' log afterward reveals interesting items :
  

  <br />
hdd: PHILIPS XBOX DVD DRIVE, ATAPI CD/DVD-ROM drive<br />
hdd: host max PIO5 wanted PIO255(auto-tune) selected PIO4<br />
hdd: UDMA/33 mode selected<br />
[...]<br />
hdd: ATAPI DVD-ROM drive, 128kB Cache<br />

  Why is that interesting ? When is the last time to saw disk devices prefixed by ‘hd’ rather than ‘sd’ ? Blast from the past. Oh, and the optical drive’s vendor string clearly indicates that this is an Xbox drive saying ‘hi !’.

  Time To Read
  When I first studied an Xbox disc in a normal optical drive, I noticed that I was able to read 6992 2048-byte sectors — about 14 MB of data — as reported by the disc table of contents (TOC). This is just enough data to play a standard DVD video animation that kindly instructs the viewer to please use a proper Xbox. At this point, I estimated that there must be something special about Xbox optical drive firmware that knows how to read alternate information on these discs and access further sectors.

  I ran my TOC query tool with an Xbox Magazine demo disc in the optical drive and it reported substantially more than 6992 sectors, enough to account for more than 2 GB of data. That’s promising. I then tried running 'dd' against the device and it was able to read… about 14 MB, an exact quantity of bytes that, when divided by 2048 bytes/sector, yields 6992 sectors.

  Future (Past ?) Work
  Assuming Google is your primary window into the broader internet, the world is beginning to lose its memory of things pertaining to the original Xbox (Microsoft’s naming scheme certainly doesn’t help searches). What I’m saying is that it can be difficult to find information about this stuff now. However, I was able to learn that a host needs to perform a sort of cryptographic handshake with the drive at the SCSI level before it is allowed to access the forbidden areas of the disc. I think. I’m still investigating this and will hopefully post more soon.