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• How to change the stream info and codec info of mp4 via Ffmpeg mux/remux code ?

  2 avril 2017, par Gohan1987

  Is it really possible to change stream information and video codec information using FFMPEG muxing / remixing code ?

  Consider this example :
  Major brand : isom
  Minor version : 0
  Compatible brand : isommp41
  Resolution : 1280 x 780

  Convert into another mp4 file
  Major brand : mp42
  Minor version : 512
  Compatible brand : isomavc1mp41
  Resolution : 359 x 288

  Note : without command line. Like using decode, sws_scale code wise ?.

• ffmpeg audio video synchronisation mux

  19 juillet 2013, par Rahul Kumar

  I am trying to mux audio and video but the resultant is not what expected. The video is not shown in the output.

  rahul@hp : $ ffmpeg -i /Desktop/a.m4a -i /Desktop/a.mp4 -acodec copy -vcodec copy /Desktop/output.mkv
  ffmpeg version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
    built on Apr  2 2013 17:00:59 with gcc 4.6.3
  *** THIS PROGRAM IS DEPRECATED ***
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/home/rahul/Desktop/a.m4a' :
    Metadata :
      major_brand : dash
      minor_version : 0
      compatible_brands : iso6mp41
      creation_time : 2013-05-17 06:34:22
    Duration : 00:16:41.01, start : 500.506122, bitrate : 127 kb/s
      Stream #0.0(und) : Audio : aac, 44100 Hz, stereo, s16
      Metadata :
        creation_time : 2013-05-17 06:34:22
  Seems stream 0 codec frame rate differs from container frame rate : 47.95 (48000/1001) -> 23.97 (45000/1877)
  
  Input #1, mov,mp4,m4a,3gp,3g2,mj2, from '/home/rahul/Desktop/a.mp4' :
  
    Metadata :
  
      major_brand : dash
  
      minor_version : 0
  
      compatible_brands : iso6avc1mp41
  
      creation_time : 2013-05-17 06:34:22
  
    Duration : 00:16:40.61, start : 500.316311, bitrate : 675 kb/s
  
      Stream #1.0(und) : Video : h264 (Main), yuv420p, 1280x720, 23.97 tbr, 90k tbn, 47.95 tbc
  
      Metadata :
  
        creation_time : 2013-05-17 06:34:22
  
  Output #0, matroska, to '/home/rahul/Desktop/output.mkv' :
  
    Metadata :
  
      major_brand : dash
  
      minor_version : 0
  
      compatible_brands : iso6mp41
  
      creation_time : 2013-05-17 06:34:22
  
      encoder : Lavf53.21.1
  
      Stream #0.0(und) : Video : avc1 / 0x31637661, yuv420p, 1280x720, q=2-31, 1k tbn, 23.98 tbc
  
      Metadata :
  
        creation_time : 2013-05-17 06:34:22
  
      Stream #0.1(und) : Audio : aac, 44100 Hz, stereo
  
      Metadata :
  
        creation_time : 2013-05-17 06:34:22
  
  Stream mapping :
  
    Stream #1.0 -> #0.0
  
    Stream #0.0 -> #0.1
  
  Press ctrl-c to stop encoding
  
  frame=    0 fps=  0 q=-1.0 Lsize=   15643kB time=500.51 bitrate= 256.0kbits/s    
  
  video:0kB audio:15493kB global headers:0kB muxing overhead 0.967810%
  
  rahul@hp : $
  

  i tried using

  -map 0:v:0

  -map 1:v:0

  -map 0:v:1

  but all showed

  Number of stream maps must match number of output streams
  

• Why when recording video using ffmpeg command line when playing the video it's running very fast ?

  31 mai 2013, par Revuen Ben Dror

  This is my code in Form1 :

  private void StartRecording_Click(object sender, EventArgs e)
  
          {
  
  
  
              ffmp.Start("test.avi", 25);
  
              timer1.Enabled = true;
  
          }

  The timer tick event :

  private void timer1_Tick(object sender, EventArgs e)
  
          {
  
              using (bitmap = (Bitmap)ScreenCapture.CaptureScreen(true))//(Bitmap)ScreenCapture.CaptureScreen(true))
  
              {
  
              ffmp.PushFrame(bitmap);
  
              }  
  
  
  
          }

  Then the code in the ffmpeg class i did :

  namespace ScreenVideoRecorder
  
  {
  
      class Ffmpeg
  
      {
  
          NamedPipeServerStream p;
  
          String pipename = "mytestpipe";
  
          byte[] b;
  
          //int i, j;
  
          System.Diagnostics.Process process;
  
          //IAsyncResult ar;
  
  
  
          public Ffmpeg()
  
          {
  
  
  
          }
  
  
  
          public void Start(string FileName, int BitmapRate)
  
          {
  
              p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
  
              b = new byte[1920 * 1080 * 3]; // some buffer for the r g and b of pixels of an image of size 720p 
  
              process = new System.Diagnostics.Process();
  
              //process.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
  
              process.StartInfo.FileName = @"D:\pipetest\pipetest\ffmpegx86\ffmpeg.exe";
  
              process.EnableRaisingEvents = false;
  
              process.StartInfo.WorkingDirectory = @"D:\pipetest\pipetest\ffmpegx86";
  
              process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;
  
              process.Start();
  
              process.StartInfo.UseShellExecute = false;
  
              process.StartInfo.CreateNoWindow = false;
  
              //ar = p.BeginWaitForConnection(EndWait,null);
  
              p.WaitForConnection();
  
          }
  
  
  
          public void PushFrame(Bitmap bmp)
  
          {
  
  
  
              int length;
  
              // Lock the bitmap's bits.
  
              //bmp = new Bitmap(1920, 1080);
  
              Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
  
              //Rectangle rect = new Rectangle(0, 0, 1280, 720);
  
              System.Drawing.Imaging.BitmapData bmpData =
  
                  bmp.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadOnly,
  
                  bmp.PixelFormat);
  
  
  
              int absStride = Math.Abs(bmpData.Stride);
  
              // Get the address of the first line.
  
              IntPtr ptr = bmpData.Scan0;
  
  
  
              // Declare an array to hold the bytes of the bitmap.
  
              //length = 3 * bmp.Width * bmp.Height;
  
              length = absStride * bmpData.Height;
  
              byte[] rgbValues = new byte[length];
  
  
  
              //Marshal.Copy(ptr, rgbValues, 0, length);
  
              int j = bmp.Height - 1;
  
              for (int i = 0; i < bmp.Height; i++)
  
              {
  
                  IntPtr pointer = new IntPtr(bmpData.Scan0.ToInt32() + (bmpData.Stride * j));
  
                  System.Runtime.InteropServices.Marshal.Copy(pointer, rgbValues, absStride * (bmp.Height - i - 1), absStride);
  
                  j--;
  
              }
  
  
  
              p.Write(rgbValues, 0, length);
  
  
  
              bmp.UnlockBits(bmpData);

  The ffmpeg command line is :

  process.StartInfo.Arguments = @"-f rawvideo -pix_fmt bgr0 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v libx264 -r " + BitmapRate + " " + FileName;

  And i checked with a breakpoint and saw that the variable BitmapRate is 25 .
  And the timer interval is 40 .

  So it should fit for 25 frames per seconds.
  But when i'm running the video file using MPC Media Player Class everything in the video is running very fast. I mean the video is 2,326KB size the video Length is 16 seconds .

  And everything in the video seems to mvoe very fast if i opend a new window or dragged a window somewhere in the screen i see it moving very fast and as it i moved and did everything in real .

  I see on the video file details that : length 16 seconds. 1920x1080 and 25 frames per second.

  So where is the problem ? i can't figure out.