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• Slicing an AVI file

  7 novembre 2014, par Peter Lur

  I am trying to upload only a certain part of an AVI file on the server without having to upload the whole file first.

  If I set the slice to the beginning (byte : 0), I can read the resulting file no problem even if I slice it in any size. However if the slice start anywhere but not at byte 0, the file become unreadable. I guess this has something to do with the avi header/index being messed up. I was wondering maybe I could use ffmpeg to move the header or something ?

  HTML Source

      
  
          
  
          <code class="echappe-js">&lt;script type=&quot;text/javascript&quot;&gt;<br />
  
  <br />
  
              window.BlobBuilder = window.MozBlobBuilder || window.WebKitBlobBuilder || window.BlobBuilder;<br />
  
  <br />
  
              function sendRequest() {<br />
  
                  var blob = document.getElementById('fileToUpload').files[0];<br />
  
  <br />
  
  <br />
  
                  //Slicing parameters<br />
  
  <br />
  
  <br />
  
                  //#1: Starting at byte:0 = WORKING WELL<br />
  
                  var start = 0;<br />
  
                  var end = 1048576;  // 1MB chunk sizes.<br />
  
  <br />
  
  <br />
  
                  //#2: Slicing the video file somewhere else (FAIL)<br />
  
  <br />
  
                  /*<br />
  
                  var start = 1048576*3;<br />
  
                  var end = 1048576*4;<br />
  
                  */<br />
  
  <br />
  
  <br />
  
                  var chunk = blob.slice(start, end, 'video/avi');<br />
  
                  uploadFile(chunk);<br />
  
  <br />
  
              }<br />
  
  <br />
  
              function fileSelected() {<br />
  
                  var file = document.getElementById('fileToUpload').files[0];<br />
  
                  if (file) {<br />
  
                      var fileSize = 0;<br />
  
                      if (file.size &gt; 1024 * 1024)<br />
  
                          fileSize = (Math.round(file.size * 100 / (1024 * 1024)) / 100).toString() + 'MB';<br />
  
                      else<br />
  
                          fileSize = (Math.round(file.size * 100 / 1024) / 100).toString() + 'KB';<br />
  
  <br />
  
                      document.getElementById('fileName').innerHTML = 'Name: ' + file.name;<br />
  
                      document.getElementById('fileSize').innerHTML = 'Size: ' + fileSize;<br />
  
                      document.getElementById('fileType').innerHTML = 'Type: ' + file.type;<br />
  
                  }<br />
  
              }<br />
  
  <br />
  
              function uploadFile(blobFile) {<br />
  
                  //var file = document.getElementById('fileToUpload').files[0];  <br />
  
                  var fd = new FormData();<br />
  
                  fd.append(&quot;fileToUpload&quot;, blobFile);<br />
  
  <br />
  
                  var xhr = new XMLHttpRequest();<br />
  
                  xhr.upload.addEventListener(&quot;progress&quot;, uploadProgress, false);<br />
  
                  xhr.addEventListener(&quot;load&quot;, uploadComplete, false);<br />
  
                  xhr.addEventListener(&quot;error&quot;, uploadFailed, false);<br />
  
                  xhr.addEventListener(&quot;abort&quot;, uploadCanceled, false);<br />
  
                  xhr.open(&quot;POST&quot;, &quot;upload.php&quot;);<br />
  
                  xhr.onload = function(e) {<br />
  
                    //alert(&quot;loaded!&quot;);<br />
  
                    };<br />
  
  <br />
  
                  xhr.send(fd);<br />
  
                  //alert(&quot;oen over&quot;);<br />
  
              }<br />
  
  <br />
  
              function uploadProgress(evt) {<br />
  
                  if (evt.lengthComputable) {<br />
  
                      var percentComplete = Math.round(evt.loaded * 100 / evt.total);<br />
  
                      document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';<br />
  
                  }<br />
  
                  else {<br />
  
                      document.getElementById('progressNumber').innerHTML = 'unable to compute';<br />
  
                  }<br />
  
              }<br />
  
  <br />
  
              function uploadComplete(evt) {<br />
  
                  /* This event is raised when the server send back a response */<br />
  
                  //alert(evt.target.responseText);<br />
  
              }<br />
  
  <br />
  
              function uploadFailed(evt) {<br />
  
                  alert(&quot;There was an error attempting to upload the file.&quot;);<br />
  
              }<br />
  
  <br />
  
              function uploadCanceled(evt) {<br />
  
                  xhr.abort();<br />
  
                  xhr = null;<br />
  
                  //alert(&quot;The upload has been canceled by the user or the browser dropped the connection.&quot;);<br />
  
              }<br />
  
          &lt;/script&gt;
  
              
  
                  Select a File to Upload
  
                  
                  
              
              
  
              
  
              
  
              
  
                  
              
              
  
          
  

  PHP Source (upload.php)

  <?php
  
  
  
  $tmp_name = $_FILES['fileToUpload']['tmp_name'];
  
  $size = $_FILES['fileToUpload']['size'];
  
  $name = $_FILES['fileToUpload']['name'];
  
  
  
  $target_file = basename($name);
  
  
  
  $complete = "complete.avi";
  
  $com = fopen($complete, "ab");
  
  
  
  // Open temp file
  
  $out = fopen($target_file, "wb");
  
  
  
  if ( $out ) {
  
      // Read binary input stream and append it to temp file
  
      $in = fopen($tmp_name, "rb");
  
      if ( $in ) {
  
          while ( $buff = fread( $in, 1048576 ) ) {
  
              fwrite($out, $buff);
  
              fwrite($com, $buff);
  
          }   
  
      }
  
      fclose($in);
  
      fclose($out);
  
  }
  
  fclose($com);
  
  
  
  ?>

• How to reduce size of moov atom of H.264 movies to improve streaming start for smartphones ?

  12 mars 2023, par Andrey Lebedev

  We run a video service streaming movies to smartphones (iOS&Android).
We are encoding in H.264+AAC and using the mp4 container.
We have a problem that long movies (60 minutes+) take a very long time to
start playing and have tracked this down to the large size of moov
atom for these movies.
For 110 minute movies the atom is as large as 4.2Mb which obviously takes a long
time to download to a smart-phone over 3G !

  



  Is there anyway to make the moov atom smaller ? We can reduce it bit
by dropping the audio sampling rate, but obviously anything below 22kHz
would not really be acceptable.

  



  We are using ffmpeg as the encoder, and MP4Box to move the metadata
to the front of the file. Is there any way to get it to make
a smaller moov ? Any other encoders out there which make a smaller moov ?

  



  For example...

  



  Big size (280 Mb, 1h 49min) streamable mp4 (h.264, AAC) file have a big header size (4.2 Mb). File was encoded by two pass ffmpeg and MP4Box for replacing metadata into beginning of the file :

  



  /usr/bin/ffmpeg -i /var/lib/encoder/incoming/2388 -aspect 320:210 -threads 8 -vcodec libx264 -profile baseline -level 13 -flags +loop+mv4 -cmp 256 -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -me_method hex -subq 7 -trellis 1 -refs 5 -bf 0 -me_range 16 -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10 -qmax 51 -qdiff 4 -b:v 270k -maxrate 270k -bufsize 270k -g 30 -passlogfile /tmp/mediaservice/3100/video-IPH.ffmpeg -an -f rawvideo -pass 1 -y /dev/null

/usr/bin/ffmpeg -i /var/lib/encoder/incoming/2388 -aspect 320:210 -threads 8 -vcodec libx264 -profile baseline -level 13 -flags +loop+mv4 -cmp 256 -partitions +parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 -me_method hex -subq 7 -trellis 1 -refs 5 -bf 0 -me_range 16 -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -qmin 10 -qmax 51 -qdiff 4 -b:v 270k -maxrate 270k -bufsize 270k -g 30 -passlogfile /tmp/mediaservice/3100/video-IPH.ffmpeg -acodec libfaac -ac 2 -b:a 32k -ar 44100 -f mp4 -pass 2 -y /var/lib/encoder/encoded/3100/video-IPH.mp4

/usr/bin/MP4Box -quiet -tmp /tmp/mediaservice/3100/ -inter 500 /var/lib/encoder/encoded/3100/video-IPH.mp4


  



  Media info (audio sample rate = 44100) :

  



  General
Count                                    : 278
Count of stream of this kind             : 1
Kind of stream                           : General
Kind of stream                           : General
Stream identifier                        : 0
Count of video streams                   : 1
Count of audio streams                   : 1
Video_Format_List                        : AVC
Video_Format_WithHint_List               : AVC
Codecs Video                             : AVC
Audio_Format_List                        : AAC
Audio_Format_WithHint_List               : AAC
Audio codecs                             : AAC LC
Complete name                            : 1348645218_970458_2465.iph.mp4
File name                                : 1348645218_970458_2465.iph.mp4
File extension                           : mp4
Format                                   : MPEG-4
Format                                   : MPEG-4
Format/Extensions usually used           : mp4 m4v m4a m4b m4p 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma f4v
Commercial name                          : MPEG-4
Format profile                           : Base Media
Internet media type                      : video/mp4
Codec ID                                 : isom
Codec ID/Url                             : http://www.apple.com/quicktime/download/standalone.html
Codec                                    : MPEG-4
Codec                                    : MPEG-4
Codec/Extensions usually used            : mp4 m4v m4a m4b m4p 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma f4v
File size                                : 272703970
File size                                : 260 MiB
File size                                : 260 MiB
File size                                : 260 MiB
File size                                : 260 MiB
File size                                : 260.1 MiB
Duration                                 : 6556027
Duration                                 : 1h 49mn
Duration                                 : 1h 49mn 16s 27ms
Duration                                 : 1h 49mn
Duration                                 : 01:49:16.027
Overall bit rate                         : 332767
Overall bit rate                         : 333 Kbps
Stream size                              : 4230761
Stream size                              : 4.03 MiB (2%)
Stream size                              : 4 MiB
Stream size                              : 4.0 MiB
Stream size                              : 4.03 MiB
Stream size                              : 4.035 MiB
Stream size                              : 4.03 MiB (2%)
Proportion of this stream                : 0.01551
HeaderSize                               : 4230683
DataSize                                 : 268473217
FooterSize                               : 70
IsStreamable                             : Yes
File last modification date              : UTC 2012-09-26 12:38:19
File last modification date (local)      : 2012-09-26 21:38:19
Writing application                      : Lavf54.6.100

Video
Count                                    : 201
Count of stream of this kind             : 1
Kind of stream                           : Video
Kind of stream                           : Video
Stream identifier                        : 0
ID                                       : 1
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format/Url                               : http://developers.videolan.org/x264.html
Commercial name                          : AVC
Format profile                           : Baseline@L1.3
Format settings                          : 5 Ref Frames
Format settings, CABAC                   : No
Format settings, CABAC                   : No
Format settings, ReFrames                : 5
Format settings, ReFrames                : 5 frames
Format settings, GOP                     : M=1, N=30
Internet media type                      : video/H264
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Codec ID/Url                             : http://www.apple.com/quicktime/download/standalone.html
Codec                                    : AVC
Codec                                    : AVC
Codec/Family                             : AVC
Codec/Info                               : Advanced Video Codec
Codec/Url                                : http://developers.videolan.org/x264.html
Codec/CC                                 : avc1
Codec profile                            : Baseline@L1.3
Codec settings                           : 5 Ref Frames
Codec settings, CABAC                    : No
Codec_Settings_RefFrames                 : 5
Duration                                 : 6556017
Duration                                 : 01:49:16.017
Bit rate                                 : 270000
Bit rate                                 : 270 Kbps
Width                                    : 480
Width                                    : 480 pixels
Height                                   : 270
Height                                   : 270 pixels
Pixel aspect ratio                       : 1.000
Display aspect ratio                     : 1.778
Display aspect ratio                     : 16:9
Rotation                                 : 0.000
Frame rate mode                          : CFR
Frame rate mode                          : Constant
FrameRate_Mode_Original                  : VFR
Frame rate                               : 29.970
Frame rate                               : 29.970 fps
Frame count                              : 196484
Resolution                               : 8
Resolution                               : 8 bits
Colorimetry                              : 4:2:0
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8
Bit depth                                : 8 bits
Scan type                                : Progressive
Scan type                                : Progressive
Interlacement                            : PPF
Interlacement                            : Progressive
Bits/(Pixel*Frame)                       : 0.070
Stream size                              : 220159060
Stream size                              : 210 MiB (81%)
Stream size                              : 210 MiB
Stream size                              : 210 MiB
Stream size                              : 210 MiB
Stream size                              : 210.0 MiB
Stream size                              : 210 MiB (81%)
Proportion of this stream                : 0.80732
Writing library                          : x264 - core 125
Writing library                          : x264 core 125
Writing library/Name                     : x264
Writing library/Version                  : core 125
Encoding settings                        : cabac=0 / ref=5 / deblock=1:0:0 / analyse=0x1:0x131 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=8 / lookahead_threads=1 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=30 / keyint_min=16 / scenecut=40 / intra_refresh=0 / rc_lookahead=30 / rc=2pass / mbtree=1 / bitrate=270 / ratetol=1.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=270 / vbv_bufsize=270 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Tagged date                              : UTC 2012-09-25 07:21:37

Audio
Count                                    : 169
Count of stream of this kind             : 1
Kind of stream                           : Audio
Kind of stream                           : Audio
Stream identifier                        : 0
ID                                       : 2
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Commercial name                          : AAC
Format profile                           : LC
Codec ID                                 : 40
Codec                                    : AAC LC
Codec                                    : AAC LC
Codec/Family                             : AAC
Codec/CC                                 : 40
Duration                                 : 6556027
Duration                                 : 1h 49mn
Duration                                 : 1h 49mn 16s 27ms
Duration                                 : 1h 49mn
Duration                                 : 01:49:16.027
Bit rate mode                            : VBR
Bit rate mode                            : Variable
Bit rate                                 : 58955
Bit rate                                 : 59.0 Kbps
Maximum bit rate                         : 270000
Maximum bit rate                         : 270 Kbps
Channel(s)                               : 2
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Channel positions                        : 2/0/0
Sampling rate                            : 44100
Sampling rate                            : 44.1 KHz
Samples count                            : 289120791
Compression mode                         : Lossy
Compression mode                         : Lossy
Stream size                              : 48314149
Stream size                              : 46.1 MiB (18%)
Stream size                              : 46 MiB
Stream size                              : 46 MiB
Stream size                              : 46.1 MiB
Stream size                              : 46.08 MiB
Stream size                              : 46.1 MiB (18%)
Proportion of this stream                : 0.17717
Tagged date                              : UTC 2012-09-25 07:21:37


  



  Moov atom info (/moov/trak[0] - video, /moov/trak[1] - audio) sample rate 44100 :
(look stsz and stts nodes in trak)

  



  Atom ftyp @ 0 of size: 32, ends @ 32
Atom moov @ 32 of size: 4230651, ends @ 4230683
     Atom mvhd @ 40 of size: 108, ends @ 148
     Atom trak @ 148 of size: 868970, ends @ 869118
         Atom tkhd @ 156 of size: 92, ends @ 248
         Atom edts @ 248 of size: 36, ends @ 284
             Atom elst @ 256 of size: 28, ends @ 284
         Atom mdia @ 284 of size: 868834, ends @ 869118
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Total size: 272703970 bytes; 50 atoms total. AtomicParsley version: 0.9.0 (utf8)
Media data: 268473217 bytes; 4230753 bytes all other atoms (1.551% atom overhead).
Total free atom space: 70 bytes; 0.000% waste. Padding available: 0 bytes.
------------------------------------------------------


  



  After reencoding this movie with audio sample rate 11025 header size much less :

  



  Media info (audio sample rate = 11025) : (crop duplicate info)

  



  General
***
HeaderSize                               : 1276359

Video
***

Audio
Count                                    : 169
Count of stream of this kind             : 1
Kind of stream                           : Audio
Kind of stream                           : Audio
Stream identifier                        : 0
ID                                       : 2
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Commercial name                          : AAC
Format profile                           : LC
Codec ID                                 : 40
Codec                                    : AAC LC
Codec                                    : AAC LC
Codec/Family                             : AAC
Codec/CC                                 : 40
Duration                                 : 6556132
Duration                                 : 1h 49mn
Duration                                 : 1h 49mn 16s 132ms
Duration                                 : 1h 49mn
Duration                                 : 01:49:16.132
Bit rate mode                            : VBR
Bit rate mode                            : Variable
Bit rate                                 : 37991
Bit rate                                 : 38.0 Kbps
Maximum bit rate                         : 128000
Maximum bit rate                         : 128 Kbps
Channel(s)                               : 2
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Channel positions                        : 2/0/0
Sampling rate                            : 11025
Sampling rate                            : 11.025 KHz
Samples count                            : 72281355
Compression mode                         : Lossy
Compression mode                         : Lossy
Stream size                              : 31134257
Stream size                              : 29.7 MiB (12%)
Stream size                              : 30 MiB
Stream size                              : 30 MiB
Stream size                              : 29.7 MiB
Stream size                              : 29.69 MiB
Stream size                              : 29.7 MiB (12%)
Proportion of this stream                : 0.12327
Tagged date                              : UTC 2012-09-25 13:20:28


  



  Moov atom info (/moov/trak[0] - video, /moov/trak[1] - audio) sample rate 11025 :

  



  Atom ftyp @ 0 of size: 32, ends @ 32
Atom moov @ 32 of size: 1276327, ends @ 1276359
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     Atom trak @ 148 of size: 821662, ends @ 821810
         Atom tkhd @ 156 of size: 92, ends @ 248
         Atom edts @ 248 of size: 36, ends @ 284
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------------------------------------------------------
Total size: 252569754 bytes; 50 atoms total. AtomicParsley version: 0.9.0 (utf8)
Media data: 251293325 bytes; 1276429 bytes all other atoms (0.505% atom overhead).
Total free atom space: 70 bytes; 0.000% waste. Padding available: 0 bytes.
------------------------------------------------------


  



  On slow connection this movie start playing after 30-40 seconds until header info (4.2 Mb) downloading. I need that movie start playing fast as it possible. And i have next questions :

  



  


  1. How reduce size of movie header ?

  


  2. How reduce size of
/moov[0]/trak[1]/mdia[0]/minf[0]/stbl[0] and why it so big when
sample rate 44100 ?

  


  


• Parallelize Youtube video frame download using yt-dlp and cv2

  4 mars 2023, par zulle99

  My task is to download multiple sequences of successive low resolution frames of Youtube videos.

  


  I summarize the main parts of the process :

  


  

  • Each bag of shots have a dimension of half a second (depending on the current fps)

  


  • In order to grab useful frames I've decided to remove the initial and final 10% of each video since it is common to have an intro and outro. Moreover

  


  • I've made an array of pair of initial and final frame to distribute the load on multiple processes using ProcessPoolExecutor(max_workers=multiprocessing.cpu_count())

  


  • In case of failure/exception I completly remove the relative directory

  


  


  The point is that it do not scale up, since while running I noticesd that all CPUs had always a load lower that the 20% more or less. In addition since with these shots I have to run multiple CNNs, to prevent overfitting it is suggested to have a big dataset and not a bounch of shots.

  


  Here it is the code :

  


  import yt_dlp
import os
from tqdm import tqdm
import cv2
import shutil
import time
import random
from concurrent.futures import ProcessPoolExecutor
import multiprocessing
import pandas as pd
import numpy as np
from pathlib import Path
import zipfile


# PARAMETERS
percentage_train_test = 50
percentage_bag_shots = 20
percentage_to_ignore = 10

zip_f_name = f'VideoClassificationDataset_{percentage_train_test}_{percentage_bag_shots}_{percentage_to_ignore}'
dataset_path = Path('/content/VideoClassificationDataset')

# DOWNOAD ZIP FILES
!wget --no-verbose https://github.com/gtoderici/sports-1m-dataset/archive/refs/heads/master.zip

# EXTRACT AND DELETE THEM
!unzip -qq -o '/content/master.zip' 
!rm '/content/master.zip'

DATA = {'train_partition.txt': {},
        'test_partition.txt': {}}

LABELS = []

train_dict = {}
test_dict = {}

path = '/content/sports-1m-dataset-master/original'

for f in os.listdir(path):
  with open(path + '/' + f) as f_txt:
    lines = f_txt.readlines()
    for line in lines:
      splitted_line = line.split(' ')
      label_indices = splitted_line[1].rstrip('\n').split(',') 
      DATA[f][splitted_line[0]] = list(map(int, label_indices))

with open('/content/sports-1m-dataset-master/labels.txt') as f_labels:
  LABELS = f_labels.read().splitlines()


TRAIN = DATA['train_partition.txt']
TEST = DATA['test_partition.txt']
print('Original Train Test length: ', len(TRAIN), len(TEST))

# sample a subset percentage_train_test
TRAIN = dict(random.sample(TRAIN.items(), (len(TRAIN)*percentage_train_test)//100))
TEST = dict(random.sample(TEST.items(), (len(TEST)*percentage_train_test)//100))

print(f'Sampled {percentage_train_test} Percentage  Train Test length: ', len(TRAIN), len(TEST))


if not os.path.exists(dataset_path): os.makedirs(dataset_path)
if not os.path.exists(f'{dataset_path}/train'): os.makedirs(f'{dataset_path}/train')
if not os.path.exists(f'{dataset_path}/test'): os.makedirs(f'{dataset_path}/test')


  


  Function to extract a sequence of continuous frames :

  


  def extract_frames(directory, url, idx_bag, start_frame, end_frame):
  capture = cv2.VideoCapture(url)
  count = start_frame

  capture.set(cv2.CAP_PROP_POS_FRAMES, count)
  os.makedirs(f'{directory}/bag_of_shots{str(idx_bag)}')

  while count < end_frame:

    ret, frame = capture.read()

    if not ret: 
      shutil.rmtree(f'{directory}/bag_of_shots{str(idx_bag)}')
      return False

    filename = f'{directory}/bag_of_shots{str(idx_bag)}/shot{str(count - start_frame)}.png'

    cv2.imwrite(filename, frame)
    count += 1

  capture.release()
  return True


  


  Function to spread the load along multiple processors :

  


  def video_to_frames(video_url, labels_list, directory, dic, percentage_of_bags):
  url_id = video_url.split('=')[1]
  path_until_url_id = f'{dataset_path}/{directory}/{url_id}'
  try:   

    ydl_opts = {
        'ignoreerrors': True,
        'quiet': True,
        'nowarnings': True,
        'simulate': True,
        'ignorenoformatserror': True,
        'verbose':False,
        'cookies': '/content/all_cookies.txt',
        #https://stackoverflow.com/questions/63329412/how-can-i-solve-this-youtube-dl-429
    }
    ydl = yt_dlp.YoutubeDL(ydl_opts)
    info_dict = ydl.extract_info(video_url, download=False)

    if(info_dict is not None and  info_dict['fps'] >= 20):
      # I must have a least 20 frames per seconds since I take half of second bag of shots for every video

      formats = info_dict.get('formats', None)

      # excluding the initial and final 10% of each video to avoid noise
      video_length = info_dict['duration'] * info_dict['fps']

      shots = info_dict['fps'] // 2

      to_ignore = (video_length * percentage_to_ignore) // 100
      new_len = video_length - (to_ignore * 2)
      tot_stored_bags = ((new_len // shots) * percentage_of_bags) // 100   # ((total_possbile_bags // shots) * percentage_of_bags) // 100
      if tot_stored_bags == 0: tot_stored_bags = 1 # minimum 1 bag of shots

      skip_rate_between_bags = (new_len - (tot_stored_bags * shots)) // (tot_stored_bags-1) if tot_stored_bags > 1 else 0

      chunks = [[to_ignore+(bag*(skip_rate_between_bags+shots)), to_ignore+(bag*(skip_rate_between_bags+shots))+shots] for bag in range(tot_stored_bags)]
      # sequence of [[start_frame, end_frame], [start_frame, end_frame], [start_frame, end_frame], ...]


      # ----------- For the moment I download only shots form video that has 144p resolution -----------

      res = {
          '160': '144p',
          '133': '240p',
          '134': '360p',
          '135': '360p',
          '136': '720p'
      }

      format_id = {}
      for f in formats: format_id[f['format_id']] = f
      #for res in resolution_id:
      if list(res.keys())[0] in list(format_id.keys()):
          video = format_id[list(res.keys())[0]]
          url = video.get('url', None)
          if(video.get('url', None) != video.get('manifest_url', None)):

            if not os.path.exists(path_until_url_id): os.makedirs(path_until_url_id)

            with ProcessPoolExecutor(max_workers=multiprocessing.cpu_count()) as executor:
              for idx_bag, f in enumerate(chunks): 
                res = executor.submit(
                  extract_frames, directory = path_until_url_id, url = url, idx_bag = idx_bag, start_frame = f[0], end_frame = f[1])
                
                if res.result() is True: 
                  l = np.zeros(len(LABELS), dtype=int) 
                  for label in labels_list: l[label] = 1
                  l = np.append(l, [shots]) # appending the number of shots taken in the list before adding it on the dictionary

                  dic[f'{directory}/{url_id}/bag_of_shots{str(idx_bag)}'] = l.tolist()


  except Exception as e:
    shutil.rmtree(path_until_url_id)
    pass


  


  Download of TRAIN bag of shots :

  


  start_time = time.time()
pbar = tqdm(enumerate(TRAIN.items()), total = len(TRAIN.items()), leave=False)

for _, (url, labels_list) in pbar: video_to_frames(
  video_url = url, labels_list = labels_list, directory = 'train', dic = train_dict, percentage_of_bags = percentage_bag_shots)

print("--- %s seconds ---" % (time.time() - start_time))


  


  Download of TEST bag of shots :

  


  start_time = time.time()
pbar = tqdm(enumerate(TEST.items()), total = len(TEST.items()), leave=False)

for _, (url, labels_list) in pbar: video_to_frames(
  video_url = url, labels_list = labels_list, directory = 'test', dic = test_dict, percentage_of_bags = percentage_bag_shots)

print("--- %s seconds ---" % (time.time() - start_time))


  


  Save the .csv files

  


  train_df = pd.DataFrame.from_dict(train_dict, orient='index', dtype=int).reset_index(level=0)
train_df = train_df.rename(columns={train_df.columns[-1]: 'shots'})
train_df.to_csv('/content/VideoClassificationDataset/train.csv', index=True)

test_df = pd.DataFrame.from_dict(test_dict, orient='index', dtype=int).reset_index(level=0)
test_df = test_df.rename(columns={test_df.columns[-1]: 'shots'})
test_df.to_csv('/content/VideoClassificationDataset/test.csv', index=True)