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• How to add arbitrary or custom metadata in MP4 ?

  13 avril 2021, par 大大大大萝卜凉

  The MP4 muxer in ffmpeg only allows certain metadata by default. I would like to add :

  


  com.android.model: Mi 10 Pro
xyz: +22.9835+113.3621/
com.android.version: 1
com.android.manufacturer: Xiaomi


  


  How can I add this with ffmpeg ?

  


• replaygain : correctly parse peak values

  4 avril 2014, par Alessandro Ghedini

  replaygain : correctly parse peak values
  According to the ReplayGain spec, the peak amplitude may overflow and may result
  
  in peak amplitude values greater than 1.0 with psychoacoustically coded audio,
  
  such as MP3. Fully compliant decoders must allow peak overflows.
  Additionally, having peak values in the 0<->UINT32_MAX scale makes it more
  
  difficult for applications to actually use the peak values (e.g. when
  
  implementing clipping prevention) since values have to be rescaled down.
  This patch corrects the peak parsing by removing the rescaling of the decoded
  
  values between 0 and UINT32_MAX and the 1.0 upper limit.
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] doc/APIchanges
  • [DBH] libavformat/replaygain.c
  • [DBH] libavutil/replaygain.h
  • [DBH] libavutil/version.h

• Problems decoding a gstreamer pipeline into images using node.js

  18 septembre 2023, par JK2018

  I have this Gstreamer pipeline that launches a test video , encodes it in h264 and sends it via udp on localhost 5000.

  


  gst-launch-1.0 -v videotestsrc ! videoconvert ! x264enc tune=zerolatency ! h264parse ! queue ! rtph264pay ! udpsink host=127.0.0.1 port=5000


  


  I run this pipeline in my terminal.

  


  Then I have a minimalistic node.js server that is suposed to receive the udp stream coming from the gstreamer pipeline, decode the video into images.
Finally I emit each image (not a fragment of an image) over a socket.

  


  I have tried several approaches unsuccessfully.
My first attempt was using a node gstreamer library and use gstreamer to decode the udp and re encode as images.

  


  My second attempt was using ffmpeg library.
Here is the code below :

  


  const express = require("express");
const http = require("http");
const { Server } = require("socket.io");
const socketIO = require("socket.io");
const cors = require("cors");
const app = express();
const server = http.createServer(app);
const dgram = require("dgram");
const ffmpeg = require("fluent-ffmpeg");

const io = socketIO(server, {
  cors: {
    origin: "http://localhost:3001",
    methods: ["GET", "POST"],
  },
});

app.use(
  cors({
    origin: "http://localhost:3001",
    methods: ["GET", "POST"],
  })
);

const udpServer = dgram.createSocket("udp4");

io.on("connection", (socket) => {
  console.log("A client connected");

  socket.on("disconnect", () => {
    console.log("A client disconnected");
  });
});

// Function to decode an H.264 video frame
function decodeH264Video(inputData, callback) {
  const command = ffmpeg()
    .input(inputData)
    .inputFormat("h264")
    .inputOptions(["-c:v h264"])
    .toFormat("image2")
    .on("end", () => {
      console.log("Decoding complete");
    })
    .on("error", (err) => {
      console.error("Error decoding video:", err);
    })
    .pipe();

  callback(command);
}

// Function to convert a decoded video frame to an image (JPEG format)
function convertVideoFrameToImage(decodedData, callback) {
  const imageStream = decodedData.pipe();
  const imageBuffer = [];

  imageStream.on("data", (chunk) => {
    imageBuffer.push(chunk);
  });

  imageStream.on("end", () => {
    const imageData = Buffer.concat(imageBuffer);
    callback(imageData);
  });
}

udpServer.on("message", (message) => {
  // Decode the UDP packet containing H.264 encoded video
  decodeH264Video(message, (decodedVideo) => {
    // Process the decoded video frame and convert it to an image
    convertVideoFrameToImage(decodedVideo, (imageData) => {
      // Send the image data to connected clients
      io.sockets.emit("image", { imageData: imageData.toString("base64") });
    });
  });
});

udpServer.bind(5000);

server.listen(3000, () => {
  console.log("Server is running on port 3000");
});


  


  Any help is more than welcome