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• ffmpeg : how to save h264 raw data as mp4 file

  15 avril 2016, par monkid

  I encode h264 data by libavcodec.
  ex.

  while (1) {
  
    ...
  
    avcodec_encode_video(pEnc->pCtx, OutBuf, ENC_OUTSIZE, pEnc->pYUVFrame);
  
    ...
  
  }

  If I directly save OutBuf data as a .264 file, it can`t be play by player. Now I want to save OutBuf

  as a mp4 file. Anyone know how to do this by ffmpeg lib ? thanks.

• Workflow and data format for sending MediaRecorder output to express server

  30 avril 2021, par Max

  I've been trying to figure this out for a while but got lost between different ways of sending files and different data formats.

  


  I am recording the stream of a canvas animation with MediaRecorder. As far as I understand this returns a blob with the video in binary format. Now I want to send this data to my express server and convert it to an h264 encoded mp4 file. My first impulse was to use ffmpeg on the server. Unfortunately I'm struggling with the details of the implementation. I am unsure on how to best transmit the data and in what format and how to feed it to ffmpeg.

  


  This is what I have on the client side :

  


  // Get stream from element
stream = element.captureStream(30)

// Create media recorder with stream
const recorder = new MediaRecorder(stream)

// Save to file
recorder.ondataavailable = ({ data }) => {
                
    const formData = new FormData()
    formData.append("file", data)

    const options = {
        method: "POST",
        body: formData,
    }

    fetch("http://localhost:3001/api/blob_to_mp4", options).then(
        (res) => {
            console.log(res)
        }
    )
}


  


  And this is what I have on the server side :

  


  "use strict";

const express = require("express");
const cors = require("cors");
const ffmpeg = require("fluent-ffmpeg");
const fs = require("fs");

const port = process.env.PORT || 3001;
const app = express();
var command = ffmpeg();

app.use(cors());
app.use(express.urlencoded({ extended: true }));
app.use(express.json());

app.post("/api/blob_to_mp4", function (req, res) {
  var data = Buffer.from("");

  // Add data
  req.on("data", function (chunk) {
    data = Buffer.concat([data, chunk]);
  });

  // Full data available
  req.on("end", () => {
    req.rawBody = data;
  });

  res.send("hello world");
});

app.listen(port);
console.log(`Server running on port ${port}`);


  


• ffmpeg AVFrame get full decoded data to char*

  28 mars 2012, par mmmaaak

  I get Frames in loop and decode it with ffmpeg getting AVFrame as e result of it.

  So I must get neccessary pixel data of frame into char* and give as a callback function's parameter. So how I can generete such char* array ? In internet I saw some examples such as :

  for(y=0; ydata[0]+y*pFrame->linesize[0], 1, width*3, pFile);}

  or something like this. Is it true ? And which size would be my char* ? As I see we write width*3 *height bytes ?