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• avformat/riffenc : don't force WAVEFORMATEXTENSIBLE for flt/dbl LPCM

  21 décembre 2023, par Gyan Doshi

  avformat/riffenc : don't force WAVEFORMATEXTENSIBLE for flt/dbl LPCM
  2c2a167ca7 forced WAVEFORMATEXTENSIBLE for all LPCM streams with greater
  
  than 16 bits per sample. However, WAVEFORMATEX allows IEEE Float samples
  
  or any depth where raw depth == coded depth, see Remarks section at
  
  https://learn.microsoft.com/en-us/windows/win32/api/mmreg/ns-mmreg-waveformatex
  
  and samples M1F1-float32-AFsp, M1F1-float64-AFsp at
  
  https://www.mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Samples.html
  There are hardware devices and likely software players requiring float samples
  
  that fail to qualify files with WAVEFORMATEXTENSIBLE headers.
  

  • [DH] libavformat/riffenc.c
  • [DH] tests/ref/acodec/pcm-f32le
  • [DH] tests/ref/acodec/pcm-f64le
  • [DH] tests/ref/seek/acodec-pcm-f32le
  • [DH] tests/ref/seek/acodec-pcm-f64le

• lavc/rawdec : Use AV_PIX_FMT_PAL8 for raw 1 bpp video in AVI

  28 janvier 2016, par Mats Peterson

  lavc/rawdec : Use AV_PIX_FMT_PAL8 for raw 1 bpp video in AVI
   From
  
  https://msdn.microsoft.com/en-us/library/windows/desktop/dd318229%28v=vs.85%29.aspx:
  "If biCompression equals BI_RGB and the bitmap uses 8 bpp or less, the
  
  bitmap has a color table immediatelly following the BITMAPINFOHEADER
  
  structure. The color table consists of an array of RGBQUAD values. The
  
  size of the array is given by the biClrUsed member. If biClrUsed is
  
  zero, the array contains the maximum number of colors for the given
  
  bitdepth ; that is, 2^biBitCount colors."
  Nothing about "monochrome" here. Unfortunately, pal8 to monow conversion
  
  seems a bit flaky, but that’s another story.
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/raw.c
  • [DH] tests/ref/vsynth/vsynth1-bpp1
  • [DH] tests/ref/vsynth/vsynth2-bpp1
  • [DH] tests/ref/vsynth/vsynth3-bpp1
  • [DH] tests/ref/vsynth/vsynth_lena-bpp1

• .NET Process - Redirect stdin and stdout without causing deadlock

  21 juillet 2017, par user1150856

  I’m trying to encode a video file with FFmpeg from frames generated by my program and then redirect the output of FFmpeg back to my program to avoid having an intermediate video file.

  However, I’ve run into what seems to be a rather common problem when redirecting outputs in System.Diagnostic.Process, mentioned in the remarks of the documentation here, which is that it causes a deadlock if run synchronously.

  After tearing my hair out over this for a day, and trying several proposed solutions found online, I still cannot find a way to make it work. I get some data out, but the process always freezes before it finishes.

  ---

  Here is a code snippet that produces said problem :

  static void Main(string[] args)
  
      {
  
  
  
          Process proc = new Process();
  
  
  
          proc.StartInfo.FileName = @"ffmpeg.exe";
  
          proc.StartInfo.Arguments = String.Format("-f rawvideo -vcodec rawvideo -s {0}x{1} -pix_fmt rgb24 -r {2} -i - -an -codec:v libx264 -preset veryfast -f mp4 -movflags frag_keyframe+empty_moov -",
  
              16, 9, 30);
  
          proc.StartInfo.UseShellExecute = false;
  
          proc.StartInfo.RedirectStandardInput = true;
  
          proc.StartInfo.RedirectStandardOutput = true;
  
  
  
          FileStream fs = new FileStream(@"out.mp4", FileMode.Create, FileAccess.Write);
  
  
  
          //read output asynchronously
  
          using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
  
          {
  
              proc.OutputDataReceived += (sender, e) =>
  
              {
  
                  if (e.Data == null)
  
                  {
  
                      outputWaitHandle.Set();
  
                  }
  
                  else
  
                  {
  
                      string str = e.Data;
  
                      byte[] bytes = new byte[str.Length * sizeof(char)];
  
                      System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
  
                      fs.Write(bytes, 0, bytes.Length);
  
                  }
  
              };
  
          }
  
  
  
  
  
          proc.Start();
  
          proc.BeginOutputReadLine();
  
  
  
          //Generate frames and write to stdin
  
          for (int i = 0; i < 30*60*60; i++)
  
          {
  
              byte[] myArray = Enumerable.Repeat((byte)Math.Min(i,255), 9*16*3).ToArray();
  
              proc.StandardInput.BaseStream.Write(myArray, 0, myArray.Length);
  
          }
  
  
  
          proc.WaitForExit();
  
          fs.Close();
  
          Console.WriteLine("Done!");
  
          Console.ReadKey();
  
  
  
      }

  Currently i’m trying to write the output to a file anyway for debugging purposes, but this is not how the data will eventually be used.

  If anyone knows a solution it would be very much appreciated.