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• How to live video stream using node API (Read file with chunk logic)

  28 septembre 2023, par Mukesh Singh Thakur

  I want to make a live video streaming API and send the video buffer chunk data to an HTML.
I am using rtsp URL.
The chunk logic does not work. The video only plays for 5 seconds then stops.

  


  index.js file

  


  const express = require('express');
const ffmpeg = require('fluent-ffmpeg');
const fs = require('fs');
const path = require('path');

const app = express();
const port = 3000;

app.get('/', (req, res) => {
  res.sendFile(__dirname + "/index.html");
});

const rtspUrl = 'rtsp://zephyr.rtsp.stream/movie?streamKey=64fd08123635440e7adc17ba31de2036';
const chunkDuration = 5; // Duration of each chunk in seconds


app.get('/video', (req, res) => {
  const outputDirectory = path.join(__dirname, 'chunks');
  if (!fs.existsSync(outputDirectory)) {
    fs.mkdirSync(outputDirectory);
  }

  const startTime = new Date().getTime();
  const outputFileName = `chunk_${startTime}.mp4`;
  const outputFilePath = path.join(outputDirectory, outputFileName);

  const command = ffmpeg(rtspUrl)
    .inputFormat('rtsp')
    // .inputOptions(['-rtsp_transport tcp'])
    .videoCodec('copy')
    .output(outputFilePath)
    .duration(chunkDuration)
    .on('start', () => {
      console.log(`start ${outputFileName}`);
    })
    .on('end', () => {
      console.log(`Chunk ${outputFileName} saved`);
      res.setHeader('Content-Type', 'video/mp4');
      res.sendFile(outputFilePath, (err) => {
        if (err) {
          console.error('Error sending file:', err);
        } else {
          fs.unlinkSync(outputFilePath); // Delete the chunk after it's sent
        }
      });
    })
    .on('error', (error) => {
      console.error('Error: ', error);
    });

  command.run();
});

app.listen(port, () => {
  console.log(`API server is running on port ${port}`);
});


  


  index.html

  


  &#xA;&#xA;&#xA;&#xA;  &#xA;  &#xA;  &#xA;  &#xA;&#xA;&#xA;&#xA;  <video width="50%" controls="controls" autoplay="autoplay">&#xA;    <source src="/video" type="video/mp4"></source>&#xA;    Your browser does not support the video tag.&#xA;  </video>&#xA;&#xA;&#xA;&#xA;

  


  package.json

  


  {
.....
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "nodemon index.js"
  },
.....
}


  


• ffmpeg - stretched pixel issue

  5 juin 2023, par Adunato

  Context

  


  I'm converting a PNG sequence into a video using FFMPEG. The images are semi-transparent portraits where the background has been removed digitally.

  


  Issue

  


  The edge pixels of the subject are stretched all the way to the frame border, creating a fully opaque video.

  


  Cause Analysis

  


  The process worked fine in the previous workflow using rembg from command line however, since I started using rembg via python script using alpha_matting to obtain higher quality results, the resulting video has these issues.

  


  The issue is present in both webm format (target) and mp4 (used for testing).

  


  Command Used

  


  Command used for webm is :

  


  ffmpeg -thread_queue_size 64 -framerate 30 -i <png sequence="sequence" location="location"> -c:v libvpx -b:v 0 -crf 18 -pix_fmt yuva420p -auto-alt-ref 0 -c:a libvorbis <png output="output">&#xA;</png></png>

  


  Throubleshooting Steps Taken

  


  

  1. PNG Visual inspection The PNG images have a fully transparent background as desired.

  


  2. PNG Alpha Measurement I have created a couple of python scripts to look at alpha level in pixels and confirmed that there is no subtle alpha level in the background pixels

  


  3. Exported MP4 with AE Using the native AE renderer the resulting MP4/H.265 has a black background, so not showing the stretched pixel issue

  


  


  Image of the Issue

  


  

  


  Sample PNG Image from sequence


  


  Code Context

  


  rembg call via API using alpha_matting seems to generate a premultiplied alpha which uses non black pixels for 0 alpha pixels.

  


  remove(input_data, alpha_matting=True, alpha_matting_foreground_threshold=250,
                    alpha_matting_background_threshold=250, alpha_matting_erode_size=12)


  


  A test using a rough RGB reset of 0-alpha pixels confirms that the images are being played with their RGB value ignoring Alpha.

  


  def reset_alpha_pixels(img):
    # Open the image file
    # Process each pixel
    data = list(img.getdata())
    new_data = []
    for item in data:
        if item[3] == 0:
            new_data.append((0, 0, 0, 0))
        else:
            new_data.append((item[0], item[1], item[2], item[3]))
        # Replace the alpha value but keep the RGB
        

    # Update the image data
    img.putdata(new_data)

    return img


  


  Updates

  


  

  • Added python context to make the question more relevant within SO scope.

  


  


• How to prepare media stream to play using dash.js web player ?

  7 avril 2016, par Paweł Tobiszewski

  I want to stream media from nginx server to Android device and play it using web player embedded into web page. Player I want to use is dash.js.
  I play the same media also using different methods (MediaPlayer and ExoPlayer) and they are working great. But when I try to use dash.js, I faced problem with codecs - they are not supported.
  I prepare my streams using ffmpeg and MP4Box, I also tried different codecs, like libx264, x264, x265 - always with the same effect.
  My based media are video in Y4M format and audio in WAV.
  How to encode it to use it in dash.js player ?

  EDIT :
  I get error "Video Element Error : MEDIA_ERR_DECODE" while trying to decode video stream.

  Here is full log :

  [16] EME detected on this user agent! (ProtectionModel_21Jan2015) 
  
  [19] Playback Initialized 
  
  [28] [dash.js 2.0.0] MediaPlayer has been initialized 
  
  [102] Parsing complete: ( xml2json: 3ms, objectiron: 3ms, total: 0.006s) 
  
  [103] Manifest has been refreshed at Thu Apr 07 2016 22:02:52 GMT+0200 (CEST)[1460059372.696]  
  
  [107] SegmentTimeline detected using calculated Live Edge Time 
  
  [118] MediaSource is open! 
  
  [118] [object Event] 
  
  [119] Duration successfully set to: 18.58 
  
  [119] Added 0 inline events 
  
  [120] video codec: video/mp4;codecs="avc1.640032" 
  
  [132] Schedule controller stopping for video 
  
  [137] No audio data. 
  
  [137] No text data. 
  
  [137] No fragmentedText data. 
  
  [137] No embeddedText data. 
  
  [138] No muxed data. 
  
  [139] Start Event Controller 
  
  [141] Schedule controller starting for video 
  
  [143] Native video element event: play 
  
  [144] Schedule controller starting for video 
  
  [148] loaded video:InitializationSegment:NaN (200, 0ms, 7ms) 
  
  [149] Initialization finished loading 
  
  [154] Getting the request for video time : 0 
  
  [155] SegmentList: 0 / 18.58 
  
  [164] loaded video:MediaSegment:0 (200, 7ms, 1ms) 
  
  [169] Native video element event: loadedmetadata 
  
  [171] Starting playback at offset: 0 
  
  [175] Got enough buffer to start. 
  
  [175] Buffered Range: 0 - 0.999999 
  
  [179] Requesting seek to time: 0 
  
  [181] Prior to making a request for time, NextFragmentRequestRule is aligning index handler's currentTime with bufferedRange.end. 0  was changed to  0.999999 
  
  [182] Getting the request for video time : 0.999999 
  
  [183] SegmentList: 0 / 18.58 
  
  [183] Getting the next request at index: 1 
  
  [184] SegmentList: 1 / 18.58 
  
  [190] loaded video:MediaSegment:1 (200, 5ms, 0ms) 
  
  [192] Buffered Range: 0 - 0.999999 
  
  [195] Getting the request for video time : 2 
  
  [196] Index for video time 2 is 1 
  
  [197] SegmentList: 1 / 18.58 
  
  [197] Getting the next request at index: 2 
  
  [198] SegmentList: 2 / 18.58 
  
  [205] loaded video:MediaSegment:2 (200, 4ms, 1ms) 
  
  [207] Buffered Range: 0 - 0.999999 
  
  [207] Getting the request for video time : 3 
  
  [208] Index for video time 3 is 2 
  
  [208] SegmentList: 2 / 18.58 
  
  [209] Getting the next request at index: 3 
  
  [209] SegmentList: 3 / 18.58 
  
  [212] Video Element Error: MEDIA_ERR_DECODE 
  
  [212] [object MediaError] 
  
  [215] Schedule controller stopping for video 
  
  [219] Native video element event: pause