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• FFmpeg.wasm demuxing - Get encodedChunks in Javascript

  16 mars 2023, par Kevin Baving

  I am building a video editor whose process looks like this :

  


  Demuxing -> Decoding -> Editing -> Encoding -> Muxing.

  


  The demuxing and muxing process is currently done with mp4box.js. I would like to replace mp4box.js with ffmpeg.wasm. Unfortunately, I can't get along with the process.

  


  What should FFmpeg.wasm do in the demuxing process ?

  


  

  • load a .mp4 file

  


  • extract the encodedVideoChunks and store them as EncodedVideoChunk objects in an array

  


  • extract the encodedAudioChunks and store them as EncodedAudioChunk objects in an array

  


  • get some metadata like : duration, timescale, fps, track_width, track_height, codec, audio_channel_count, sample_rate ....

  


  


  public async loadFile(file: File) {
    let data = await fetchFile(file)
    let blob = new Blob();
    await this.ffmpeg.setProgress(({ratio }) => console.log(`Extracting frames: ${Math.round(ratio * 100)}%`));
    this.ffmpeg.FS('writeFile', 'videoTest.mp4', data);
    //Here is where I am struggling
    //Should look like this: 
    //const command = '-i videoTest.mp4 -c:v copy .... '
    //await this.ffmpeg.run(command);
    //....
}


  


  Lets get deeper into my problem :

  


  Because FFmpeg.wasm is still a cli tool, I have no idea what the best way to safe the encodedChunks into a file is (and what kind of filetype I should use). Further I would like to know how to read that file propertly so that i can safe the input of the file into seperate EncodedVideo- and AudioChunks.

  


• Getting Error message Unknown encoder 'libx264' , any help appreciated

  16 janvier 2022, par Alex.Foster

  I am trying to compress videos files to a target size within python using ffmpeg-python for an A level project as part of my coursework, I keep getting this error saying it doesn't know the encoder. Not sure what I'm meant to do as this is literally an entirely new space to me. Am I meant to have installed the codec or something, or is there an alternative I can use ?

  


  import os, ffmpeg
##import section:this part is where I import all of the modules I will use
import  tkinter
import shutil
from tkinter import filedialog
import os


def fileSelect():                                                                           #start of fileSelect function
    global startingLocation                                                                 #declares startingLocation as global variable
    global originalName                                                                     #declares originalName as global variable
    global fileType                                                                         #declares fileType as global variable
    startingLocation = filedialog.askopenfilename(initialdir="/", title="Select file",      #tkinter function that opens file explorer, lets user select file saves the file path as a variable
                    filetypes=(("video files", "*.mp4"),("images", "*.jpg*")))
    originalName = os.path.basename(startingLocation)                                       #os function that gets the actaul file name from the path string
    print (originalName)                                                                    #print statement to check if originalName has been found
    fileType = startingLocation.split('.')                                                  #splits original name where any full stop in found and saves array as variable
    fileType = fileType[-1]                                                                 #changes variable to have the str value of the final item in the array; the file type
    fileType = '.' + fileType                                                               #adds fullstop to the start of the file type so i dont have to repeatedly do it
    print (fileType)                                                                        #print statement to check file type is found correctly

def outputSelect():                                                                         #start of outputSelect function
     global outputLocation                                                                  #declares outputLocation as global variable
     outputLocation = filedialog.askdirectory(initialdir="/", title="Select folder")        #tkinter function that opens file explorer, lets the user select of folder as saves the folder path as a variable

def fileNewName():                                                                          #start of fileNewName function
    global customName                                                                       #declares customName as global variable
    customName = input("Enter the end name of your file")                                   #simple code assigning user input to the custom name vairable
    customName = customName + fileType                                                      #add the fileType onto the end of the custom name

def compress():                                                                             #start of compress function
    fileSelect()                                                                            #calls the fileSelect function
    outputSelect()                                                                          #calls the outputSelect function
    fileNewName()
    global src
    global dst                                                                           #calls the fileNewName function
    src = startingLocation                                                                  #assigns startingLocation str as src, so the shutil module is able to use it in a cleaner way
    dst = outputLocation                                                                    #assigns outputLocation dst as src, so the shutil module is able to use it in a cleaner way
    shutil.copy(src, dst)                                                                   #shutil command that copies the file from src to dst
    src = outputLocation + '/' + originalName                                               #reassigns src as the location of the file copy
    dst = outputLocation + '/' + customName                                                 #reassigns dst as the location of the file copy but with a new name
    shutil.move(src,dst)


def compress_video(video_full_path, output_file_name, target_size):
    # Reference: https://en.wikipedia.org/wiki/Bit_rate#Encoding_bit_rate
    min_audio_bitrate = 32000
    max_audio_bitrate = 256000

    probe = ffmpeg.probe(video_full_path)
    # Video duration, in s.
    duration = float(probe['format']['duration'])
    # Audio bitrate, in bps.
    audio_bitrate = float(next((s for s in probe['streams'] if s['codec_type'] == 'audio'), None)['bit_rate'])
    # Target total bitrate, in bps.
    target_total_bitrate = (target_size * 1024 * 8) / (1.073741824 * duration)

    # Target audio bitrate, in bps
    if 10 * audio_bitrate > target_total_bitrate:
        audio_bitrate = target_total_bitrate / 10
        if audio_bitrate < min_audio_bitrate < target_total_bitrate:
            audio_bitrate = min_audio_bitrate
        elif audio_bitrate > max_audio_bitrate:
            audio_bitrate = max_audio_bitrate
    # Target video bitrate, in bps.
    video_bitrate = target_total_bitrate - audio_bitrate

    i = ffmpeg.input(video_full_path)
    ffmpeg.output(i, os.devnull,
                  **{'c:v': 'libx264', 'b:v': video_bitrate, 'pass': 1, 'f': 'mp4'}
                  ).overwrite_output().run()
    ffmpeg.output(i, output_file_name,
                  **{'c:v': 'libx264', 'b:v': video_bitrate, 'pass': 2, 'c:a': 'aac', 'b:a': audio_bitrate}
                  ).overwrite_output().run()

compress()
compress_video(dst, outputLocation, 3 * 1000)


  


• Rendering video by ffmpeg.wasm in browser occured an error

  15 septembre 2022, par James Bor

  When a local video renderer uses the ffmpeg.wasm library in the Chrome browser, very often an error with the SBOX_FATAL_MEMORY_EXCEEDED code occurs during the rendering process. The standard command set is used. The code below is half fake because it is very long, but describes an approximate action algorithm. Computer performance and RAM capacity do not affect the video, files used - minimal size. Has anyone experienced this and how can we solve it ?
Error screen

  


  const videoGenerate = async (project) => {
  const ffmpeg = createFFmpeg({
      corePath: 'ffmpeg/ffmpeg-core.js',
      workerPath: 'ffmpeg/ffmpeg-core.worker.js'
  });
  await loadFfmpeg(ffmpeg);
  project.projectName = "Default";
  project.fileType = "video/mp4";

  const resultVideo = {
    title: `${project.projectName}ConcatenatedVideo.mp4`,
  };
  // *For fetchFile method and ffmpeg.FS('writeFile', title, file);
  await uploadObjects(project.projectName, ffmpeg);
  // *
  const command = ['-i', project.video, resultVideo.title];
  await ffmpeg.run(...command);
  await ffmpeg.FS("unlink", resultVideo.title);
  resultVideo["blob"] = ffmpeg.FS('readFile', title);
  return resultVideo.blob;
};


  


  These dependencies are used : "@ffmpeg/core" : " 0.8.5", "@ffmpeg/ffmpeg" : " 0.9.7". Upgrading the library to the latest version does not work either.