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• how to pipe ffmpeg to ffmpeg ?

  4 juillet 2022, par imagesck

  How to pipe ffmpeg output frame by frame to ffmpeg ? i dont see any library either nodejs or python that as powerfull as the application directly. so what i need to do is take rawvideo from ffmpeg, then manipulate in middle stage, then push again that buffer to ffmpeg. i got inavlid buffer size after encode 24 frames. is stdin buffer push too fast ?

  


  const { spawn } = require('child_process');
const path = require('path');

const decArgs = [
    '-i', path.join(__dirname + '/public/blackpink.mp4'),
    '-c:v', 'copy',
    '-an',
    '-f', 'rawvideo',
    '-'
];

const decode = spawn('ffmpeg', decArgs);

const encArgs = [
    '-f', 'rawvideo',
    '-video_size', '854x480',
    '-i', '-',
    '-c:v', 'libx264',
    '-preset', 'ultrafast',
    '-crf', '30',
    '-pix_fmt', 'yuv420p',
    '-y',
    path.join(__dirname + '/public/output.mp4')
];

const encode = spawn('ffmpeg', encArgs, {
    stdio: [
        decode.stdout,
        null,
        null
    ]
})

encode.stderr.on('data', data => {
    console.log(data.toString())
})


  


• How to pipe FFmpeg output to C# System.Io.Stream ?

  26 juin 2022, par Maximilian Schüller

  I wrote a program using C# that downloads an audio file in WebM format from YouTube. Now I don't want to have the entire audio track, just a small section of it. I already found a thread explaining how to transfer the stream in FFmpeg. After this process I want to forward the cropped file to a client. How can I direct the output to a stream after FFmpeg is done ?

  


  From the answer of the thread mentioned above, I adapted the following code for myself :

  


  var inputArgs = "-ss 60 -t 10 -i -";
var outputArgs = "-f webm_chunk pipe:.webm";

var process = new Process()
{
    StartInfo =
    {
        FileName = "ffmpeg.exe",
        Arguments = $"{inputArgs} {outputArgs}",
        UseShellExecute = false,
        CreateNoWindow = true,
        RedirectStandardInput = true,
        RedirectStandardOutput = true,
        RedirectStandardError = true
    }
};
process.Start();

var ffmpegIn = process.StandardInput.BaseStream;
var ffmpegOut = process.StandardOutput.BaseStream;
var ffmpegErr = process.StandardError.BaseStream;

stream.Seek(0,SeekOrigin.Begin);
stream.CopyTo(ffmpegIn);

ffmpegIn.Flush();
ffmpegIn.Close();

process.WaitForExit();


  


  But when I try this way, I get an error :

  


    built with gcc 11.2.0 (crosstool-NG 1.24.0.533_681aaef)
  configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static --pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64 --target-os=mingw32 --enable-version3 --disable-debug --enable-shared --disable-static --disable-w32threads --enable-pthreads --enable-iconv --enable-libxml2 --enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp --enable-lzma --enable-fontconfig --enable-libvorbis --enable-opencl --disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib --enable-amf --enable-libaom --enable-libaribb24 --disable-avisynth --enable-libdav1d --disable-libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm --disable-frei0r --enable-libgme --enable-libass --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librist --enable-libtheora --enable-libvpx --enable-libwebp --enable-lv2 --enable-libmfx --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e --disable-librubberband --enable-schannel --enable-sdl2 --enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame --enable-libuavs3d --disable-libdrm --disable-vaapi --disable-libvidstab --enable-vulkan --enable-libshaderc --enable-libplacebo --disable-libx264 --disable-libx265 --disable-libxavs2 --disable-libxvid --enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC --extra-cxxflags= --extra-ldflags=-pthread --extra-ldexeflags= --extra-libs=-lgomp --extra-version=20220626
  libavutil      57. 17.100 / 57. 17.100
  libavcodec     59. 18.100 / 59. 18.100
  libavformat    59. 16.100 / 59. 16.100
  libavdevice    59.  4.100 / 59.  4.100
  libavfilter     8. 24.100 /  8. 24.100
  libswscale      6.  4.100 /  6.  4.100
  libswresample   4.  3.100 /  4.  3.100
Input #0, matroska,webm, from 'pipe:':
  Metadata:
    encoder         : google/video-file
  Duration: 00:03:14.16, start: -0.007000, bitrate: N/A
  Stream #0:0(eng): Audio: opus, 48000 Hz, stereo, fltp (default)
Output #0, webm_chunk, to 'pipe:.webm':
Output file #0 does not contain any stream


  


  I found a thread while searching that brought me to the RedirectStandardOutput option. But I don't understand this error.

  


• Pipe ffmpeg process with node js

  20 juin 2022, par Max

  When I make request to route, spawn process and pipe it directly to response, it works perfectly fine and creates livestream. However, it takes some time to start process and buffer some data to start playing video.

  


  app.get("/stream", async (req, res) => {
  const url = "rtsp://213.3.38.11/axis-media/media.amp";

  const cmd = [
    "-re",
    "-loglevel",
    "debug",
    "-reorder_queue_size",
    "5",
    "-rtsp_transport",
    "tcp",
    "-i",
    `${url}`,
    "-c:v",
    "copy",
    "-c:a",
    "aac",
    "-f",
    "mp4",
    "-movflags",
    "+frag_keyframe+empty_moov+default_base_moof",
    "pipe:1",
  ];

  const child = spawn("ffmpeg", cmd, {
    stdio: ["ignore", "pipe", process.stderr],
  });

  child.stdio[1].pipe(res)l

  res.on("close", () => {
    child.stdio[1].unpipe(res);
  });
});



  


  I would like to create process while starting server so I can pipe it whenever I make request to that route, but when I do so, process is living for a few seconds then stops using cpu. Sometimes it lives, but dies when I make request and try piping it.