Newest 'ffmpeg' Questions - Stack Overflow

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• How does record functionality in vlc works [on hold]

  14 décembre 2013, par quartz

  I am curious about how does "record" functionality of vlc works.
  1) Does it work like screen capture software like "recordmydesktop" ?
  or
  2) Does it save in-memory the frames and latter combine it with tools like ffmpeg?
  or
  3) Does it simply copy the required information from original video to new video file?

  Or something else?

  I want to know these informations because I am developing some simulation tool using a rendering engine. I want my render output to be stored directly in a video file rather than displayed on monitor. If I know these informations, I think it will help.

  Just give me hints, I don't need complete answer. This question is not too broad, since I asked specifically about record functionality of vlc media player.

• C# Desktop recorder h.264 cross-"computer"

  14 décembre 2013, par rodi

  I was looking for a method with "least requirements" for a maximum compatibility.

  I have seen that there are mainly 2 ways: through directx, through .NET ( only >Win7) but both requires Win7 Or DirectX 9 installed.

  could ffmpeg be useful? I have tried following this Wiki, but it prompts me:

  > ffmpeg -f dshow -i video="UScreenCapture":audio="Microphone" output.flv
  
  [dshow @ 00000000003ea700] Could not find video device.
  video=UScreenCapture: Input/output error
  

  Any advice?

• Killing infinite ffmpeg on the command line from an application

  14 décembre 2013, par bhupinder

  I am using

  ffmpeg.exe -f dshow -i audio=virtual-audio-capturer -q 4 -y -tune zerolatency outfile.mp3
  

  to grap sound from speakers. This command runs infinitely. I have to use

  Process->kill();
  

  command to stop execution of this command in my application.

  I want to know if it is safe to kill it the way I am killing, or is there any better way?

• Using openssl with FFmpeg on Android with NDK

  14 décembre 2013, par William Seemann

  I cross compiled FFmpeg with openssl support using the scripts from the Guardian project however my code crashes whenever I execute the following:

  System.loadLibrary("crypto");    // loads OK
  System.loadLibrary("ssl");       // loads OK
  System.loadLibrary("avformat");  // crashes
  

  The error:

  dlopen("/data/data/wseemann.media.demo/lib/libavformat.so") failed: dlopen failed: cannot locate symbol "SSL_library_init" referenced by "libavformat.so"...
  

  I build libavformat with a toolchain and then run ndk-build using the following Android.mk file to create the .so files:

  LOCAL_PATH := $(call my-dir)
  
  include $(CLEAR_VARS)
  LOCAL_MODULE := libswscale
  LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
  LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
  include $(PREBUILT_SHARED_LIBRARY)
  
  include $(CLEAR_VARS)
  LOCAL_MODULE := libavcodec
  LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
  LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
  include $(PREBUILT_SHARED_LIBRARY)
  
  include $(CLEAR_VARS)
  LOCAL_MODULE := libavformat
  LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
  LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
  include $(PREBUILT_SHARED_LIBRARY)
  
  include $(CLEAR_VARS)
  LOCAL_MODULE := libavutil
  LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
  LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
  include $(PREBUILT_SHARED_LIBRARY)
  
  LOCAL_PATH:= $(call my-dir)
  

  It would seem that libavformat needs libcrypto and libssl when it is loaded but it can't find them or isn't loading them. Does anyone know how to fix this issue?

• How to extract stream of images from video file using ffmpeg

  13 décembre 2013, par user3032143

  I want to extract stream of images from a video file using ffmpeg.

  I know I can extract them straight to the hard drive using these arguments:

  -i - -qscale 1 h:\out\img-%05d.jpg

  But i would like to extract directly to a stream.

  This is my code so far:

  private void ExtractImagesFromVideo(byte[] data,string _args)
      {
          try
          {
              serverBuild = new Process();
              serverBuild.StartInfo.WorkingDirectory = Environment.CurrentDirectory;
              serverBuild.StartInfo.Arguments = _args;
              serverBuild.StartInfo.FileName = Environment.CurrentDirectory + @"\ffmpeg.exe";
              serverBuild.StartInfo.UseShellExecute = false;
              serverBuild.StartInfo.RedirectStandardOutput = true;
              serverBuild.StartInfo.RedirectStandardError = true;
              serverBuild.StartInfo.RedirectStandardInput = true;
              serverBuild.StartInfo.CreateNoWindow = true;
              serverBuild.StartInfo.LoadUserProfile = false;
              serverBuild.EnableRaisingEvents = true;
              serverBuild.Start();
  
              using (BinaryWriter bw = new BinaryWriter(serverBuild.StandardInput.BaseStream))
              {
                  bw.Write(data);
              }
  
              mStandardOutput = serverBuild.StandardOutput.BaseStream;
              mStandardOutput.BeginRead(mReadBuffer, 0, mReadBuffer.Length, StandardOutputReadCallback, null);
              serverBuild.WaitForExit();
              byte[] _data = mStandardOutputMs.ToArray();
              mStandardOutput.Close();
  
          }
          catch (Exception _ex)
          {
  
          }
          finally
          {               
              serverBuild.Dispose();
          }
      }
  

  and I call like like this:

       string _argsOut = @"-i pipe:0 -qscale 1 -f mjpeg pipe:1 ";
       ExtractImagesFromVideo(data, _argsOut);
  

  and it hangs on this line:

  bw.Write(data);
  

  thanks