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• FFMPG Concat two video quality issue

  14 novembre 2019, par Salah Hammouda

  I’m trying to concat two mp4 video files using ffmpg (with the below command), a main video and a secondary one, the main video always have 1080x1920 resolution and the resulting video should have the some resolution.

  val concat = "-i $mainVideoPath -i $secondVideoPath -filter_complex [0:v]scale=1080:1920:force_original_aspect_ratio=decrease,setsar=1:1,pad=1080:1920 :(ow-iw)/2 :(oh-ih)/2[s0] ;[1:v]scale=1080:1920:force_original_aspect_ratio=decrease,setsar=1:1,pad=1080:1920 :(ow-iw)/2 :(oh-ih)/2[s1] ;[s0][s1]concat=n=2:v=1[v] -map [v] $resultVideoPath"

  The concat work fine but the main part of my resulting video always lose quality although the resulting video has the same resolution.

  Any help will be appreciated.

• ffmpeg scaling nvenc maintaining aspect ratio

  3 novembre 2019, par Sambir

  I want to fully hw transcode mkv files to mp4 and up- /downscale the content maintaning the aspect ratio.

  With CPU based transcoding you just add :

  scale=1920:1080:force_original_aspect_ratio=decrease

  With HW (CUDA) transcoding either -resize on Decoding side or -scale_npp on encoding side is possible but both dont seem to be capable to force original acpect ratio.

  I want to for instance upscale 1920x800 file to 1920x1080 while filling the rest with black bars so I can overlay subtitles over the bars for instance...

  With this i can fully transcoding using GPU power reather than utilizing cpu. any ideas ?

• When using ffmpeg to compress and create in real time mpeg4 video file from bathc of images getting low quality video how can i improve quality ?

  30 juin 2015, par Brubaker Haim

  The goal here is to create a compressed mp4 video file in real time. I’m saving screenshots as bitmaps type on my hard disk. And i want to create mp4 file and compress the mp4 video file in real time.

  using System;
  
  using System.Windows.Forms;
  
  using System.Collections.Generic;
  
  using System.Linq;
  
  using System.Text;
  
  using System.Threading.Tasks;
  
  using System.Drawing;
  
  using System.IO.Pipes;
  
  using System.Runtime.InteropServices;
  
  using System.Diagnostics;
  
  using System.IO;
  
  using DannyGeneral;
  
  
  
  namespace Youtube_Manager
  
  {
  
      class Ffmpeg
  
      {
  
          NamedPipeServerStream p;
  
          String pipename = "mytestpipe";
  
          System.Diagnostics.Process process;
  
          string ffmpegFileName = "ffmpeg.exe";
  
          string workingDirectory;
  
  
  
          public Ffmpeg()
  
          {
  
              workingDirectory = Path.GetDirectoryName(Application.ExecutablePath);
  
              Logger.Write("workingDirectory: " + workingDirectory);
  
              if (!Directory.Exists(workingDirectory))
  
              {
  
                  Directory.CreateDirectory(workingDirectory);
  
              }
  
              ffmpegFileName = Path.Combine(workingDirectory, ffmpegFileName);
  
              Logger.Write("FfmpegFilename: " + ffmpegFileName);
  
          }
  
  
  
          public void Start(string pathFileName, int BitmapRate)
  
          {
  
              try
  
              {
  
  
  
                  string outPath = pathFileName;
  
                  p = new NamedPipeServerStream(pipename, PipeDirection.Out, 1, PipeTransmissionMode.Byte);
  
  
  
                  ProcessStartInfo psi = new ProcessStartInfo();
  
                  psi.WindowStyle = ProcessWindowStyle.Hidden;
  
                  psi.UseShellExecute = false;
  
                  psi.CreateNoWindow = false;
  
                  psi.FileName = ffmpegFileName;
  
                  psi.WorkingDirectory = workingDirectory;
  
                  psi.Arguments = @"-f rawvideo -vcodec rawvideo -pix_fmt rgb24 -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;
  
                  process = Process.Start(psi);
  
                  process.EnableRaisingEvents = false;
  
                  psi.RedirectStandardError = true;
  
                  p.WaitForConnection();
  
              }
  
              catch (Exception err)
  
              {
  
                  Logger.Write("Exception Error: " + err.ToString());
  
              }
  
          }
  
  
  
          public void PushFrame(Bitmap bmp)
  
          {
  
              try
  
              {
  
                  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);
  
              }
  
              catch(Exception err)
  
              {
  
                  Logger.Write("Error: " + err.ToString());
  
              }
  
  
  
          }
  
  
  
          public void Close()
  
          {
  
              p.Close();
  
          }
  
      }
  
  }

  The Bitmaps images files on my hard disk each one is 1920x1080 and Bit depth 32.

  The video file is on the hard disk at size 1.24MB

  This is a screenshot i took from the video file when playing it.
  You can see how bad the quality is.

  

  This is a link for 10 images of the screenshots i’m using creating from the video file. They are Bitmaps.

  Screenshots rar

  Its something with the arguments :
  This line dosen’t work when i run the program the command prompt window close at once. I can’t even see if there is any erorr/s the command prompt window close too fast.

  psi.Arguments = @"-f libx264 -vcodec libx264 -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;

  When i’m using this arguments it’s working but making bad quality video :

  psi.Arguments = @"-f rawvideo -pix_fmt bgra -video_size 1920x1080 -i \\.\pipe\mytestpipe -map 0 -c:v mpeg4 -r " + BitmapRate + " " + outPath;