Recherche avancée

Sur d’autres sites (8336)

• VB.NET - frame capture issue and syncing audio with video using ffmpeg issue

  1er décembre 2013, par Sunny D'Souza

  I have a code in VB.NET that capture fullscreen images of the desktops at regular intervals (code runs in timer tick event of 20ms) Within the same ticker event I even capture the audio.
  Code to capture the screenshots

      Filenum.Text = Filenum.Text + 1
  
      Dim screensize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
  
      Dim BMP As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
  
      Dim ga As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(BMP)
  
      ga.CopyFromScreen(New Point(0, 0), New Point(0, 0), screensize)
  
      Cursor.Draw(ga, New Rectangle(Cursor.Position, Cursor.Size))
  
      Dim fileDiro As String = My.Computer.FileSystem.CurrentDirectory + "\Recorder\VidShots-" + DT + "\img"
  
  
  
      Dim frame As String = Filenum.Text
  
      BMP.Save(fileDiro + frame + ".png")

  I notice the above code runs OK (not too much as expected) when doing regular recording of desktop but when recording a video or fast motion capture, it fails to generate enough frames to create a decent clip.

  '''' Code exclusively for Audio recording - Start audio recording - added 22/09/2013
  
  
  
   mciSendString("open new Type waveaudio Alias recsound", "", 0, 0)
  
      mciSendString("record recsound", "", 0, 0)
  
  
  
   '''' Code exclusively for Audio recording - Stop audio recording - added 22/09/2013
  
      Using w As New IO.FileStream( _
  
                      My.Computer.FileSystem.CurrentDirectory + "\Recorder\sound.mp3", _
  
                      IO.FileMode.Create _
  
                  )
  
          w.SetLength(64000)
  
      End Using
  
  
  
      Dim fP As String
  
      fP = My.Computer.FileSystem.CurrentDirectory & "\Recorder\sound.mp3"
  
      mciSendString("save recsound " & Chr(34) & fP & Chr(34), "", 0, 0)
  
      mciSendString("close recsound", "", 0, 0)
  
      My.Computer.Audio.Stop()

  The problem is when I try to mux together the audio and video using ffmpeg.exe, more often than not, the audio is out of sync with the video generated. Below are examples of the two ffmpeg statements that are executed.

   Dim startInfo As New ProcessStartInfo(My.Computer.FileSystem.CurrentDirectory & "\ffmpeg.exe")
  
         startInfo.Arguments = "-r " + max.ReadLine + " -analyzeduration 2147483647 -probesize 2147483647 -i Recorder/" + x + "/img%d.png -r 12 -b:v 900K Recorder/" + x + "/video.avi"
  
          Debug.Print(startInfo.Arguments.ToString)
  
  
  
          p = Process.Start(startInfo)
  
          p.WaitForExit()
  
          'Process.Start(My.Computer.FileSystem.CurrentDirectory & "\ffmpeg.exe", "-r 10 -analyzeduration 2147483647 -probesize 2147483647 -i Recorder/" + x + "/img%d.png -r 50 Recorder/" + x + "/video.avi"))
  
          Process.Start(My.Computer.FileSystem.CurrentDirectory & "\ffmpeg.exe", "-i Recorder/" + x + "/video.avi -i Recorder/sound.mp3 -map 0 -map 1 -codec copy -shortest Recorder/" + x + "/video1.avi")
  
          Debug.Print("-i Recorder/" + x + "/video.avi -i Recorder/sound.mp3 -map 0 -map 1 -codec copy -shortest Recorder/" + x + "/video1.avi")

  Could someone please help in getting the audio and video in sync ?

• flacdsp_lpc_template : add comment to explain the CONFIG_SMALL code

  14 février 2014, par James Darnley

  flacdsp_lpc_template : add comment to explain the CONFIG_SMALL code
  I found the optimisation of 2 samples per iteration obscured the
  
  underlying algorithm.  I had to write it out on paper and translate into
  
  a mathematical sum to see that the two samples are unconnected.  I hope
  
  that if anyone else is struggling to understand the code that this will
  
  be useful.
  Reviewed-by : Christophe Gisquet <christophe.gisquet@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/flacdsp_lpc_template.c

• ffmpeg display only video in Android

  19 février 2014, par Whoami

  I am Writing video player in android. So far i could able to capture the frames, with the help of av_read_frame and avcodec_decode_video2, and updating to SDL2.0. I have followed dranger tutorial02.c http://dranger.com/ffmpeg/ .

  Sudo Code is :

   while (1)
  
  
  
     {
  
           1. Read packet
  
           2. check if video frame; if not Go to Step 3.
  
                  2.1  if video frame, then update with SDL_UpdateYUVTexture,
  
           3. Handle SDL Event
  
           4. Clear the Renderer.
  
           5. Present Renderer. 
  
     }

  I wonder, do i need to take care of synchronization of video, dts/pts calculation while i need only to display video ?

  This scenario works well in the samsung, but not in other mobiles.

  What woud be your advice ?