Recherche avancée

Sur d’autres sites (4599)

• Solving The XVD Puzzle

  15 avril 2012, par Multimedia Mike — General, multimedi archaeology, silicon valley, vg2, xvd, zygo

  I downloaded a multimedia file a long time ago (at least, I strongly suspected it was a multimedia file which is why I downloaded it). It went by the name of ‘lamborghini_850kbps.vg2′. I have had it in my collection for at least 7 years. I couldn’t remember where I found it. I downloaded it before it occurred to me to take notes about this sort of stuff.

  I found myself staring at the file again today and Googled the filename. This led me to a few Japanese sites which also contained working URLs for a few more .vg2 samples. Some other clues led me to a Russian language forum where someone had linked to a site that had Win32 codec modules that could process the files. The site was defunct but the Internet Archive Wayback Machine kept a copy for me, as well as copies of several more .vg2 samples from a defunct Japanese site previously involved with this codec.

  Sometimes this internet technology works really well. But I digress.

  Anyway, through all this, I finally found a clue : XVD. and wouldn’t you know, there is already a basic page on the MultimediaWiki describing the technology. In fact, while VG2 is a custom container, the MultimediaWiki states that the video component has a FourCC of VGMV, and there is already a file named VGMV.avi in the root V-codecs/ samples directory, something I vow to correct (that’s a big pet peeve of mine– putting samples in the root V-codecs/ or A-codecs/ directories).

  XVD… XVD… XVD… why does that sound so familiar ? Oh, of course ; there is a company named XVD and they have an office in the Bay Area which I have passed on numerous occasions, like this morning :

  
  <

  Someone originally connected with the multimedia technology in question operates a website which contains an unofficial history of the XVD tech. At first, I was wondering if the technology was completely defunct (and should therefore be open sourced). But if XVD’s solutions page (dated 2010) is to be believed, the technology is still in service, and purported to be better than H.264 and VC-1 : “The current generation of XVD video compression technology provides better video quality at any given data rate than standards-based codecs (H.264 or VC-1) with four times lower encoding complexity (when compared with H.264 Main Profile).”

  If they say so. For my part, I’m just happy that I have finally figured out what this lamborghini_850kbps.vg2 is so that I can properly catalog it on the samples site, which I have now done, along with other samples and various codecs modules.

  This episode reminds me that there’s a branch office of Zygo Corporation close to my home (though the headquarters are far, far away). The companies you see in Silicon Valley. Anyway, long-time open source multimedia hackers will no doubt recognize Zygo from the ZyGo FourCC & video codec transported in QuickTime files that was almost decode-able using an H.263 decoder.

  
  
  

  I may never learn what Zygo’s core competency actually is, but I will always remember their multimedia tech every time I run past their office.

• AWS Lambda subprocess OSError : [Errno 2] No such file or directory

  11 septembre 2016, par Lev

  I’m trying to create a lambda function that makes collection of thumbnails from a video on amazon s3 using ffmpeg. ffmpeg binary is included into fuction package.

  function code :

  # -*- coding: utf-8 -*-
  
  
  
  import stat
  
  import shutil
  
  import boto3
  
  import logging
  
  import subprocess as sp
  
  import os
  
  import threading
  
  
  
  thumbnail_prefix = 'thumb_'
  
  thumbnail_ext = '.jpg'
  
  time_delta = 1
  
  video_frames_path = 'media/videos/frames'
  
  
  
  print('Loading function')
  
  logger = logging.getLogger()
  
  logger.setLevel(logging.INFO)
  
  
  
  lambda_tmp_dir = '/tmp'  # Lambda fuction can use this directory.
  
  
  
  # ffmpeg is stored with this script.
  
  # When executing ffmpeg, execute permission is requierd.
  
  # But Lambda source directory do not have permission to change it.
  
  # So move ffmpeg binary to `/tmp` and add permission.
  
  ffmpeg_bin = "{0}/ffmpeg.linux64".format(lambda_tmp_dir)
  
  shutil.copyfile('/var/task/ffmpeg.linux64', ffmpeg_bin)
  
  
  
  os.chmod(ffmpeg_bin, 777)
  
  
  
  # tried also:
  
  # os.chmod(ffmpeg_bin, os.stat(ffmpeg_bin).st_mode | stat.S_IEXEC)
  
  
  
  s3 = boto3.client('s3')
  
  
  
  
  
  def get_thumb_filename(num):
  
      return '{prefix}{num:03d}{ext}'.format(prefix=thumbnail_prefix, num=num, ext=thumbnail_ext)
  
  
  
  
  
  def create_thumbnails(video_url):
  
      i = 1
  
      filenames_list = []
  
      filename = None
  
      while i == 1 or os.path.isfile(os.path.join(os.getcwd(), get_thumb_filename(i-1))):
  
          if filename:
  
              filenames_list.append(filename)
  
          time = time_delta * (i - 1)
  
          filename = get_thumb_filename(i)
  
          print(ffmpeg_bin)
  
          if os.path.isfile(ffmpeg_bin):
  
              print('ok')
  
          sp.call(['sudo',
  
                   ffmpeg_bin,
  
                   '-ss',
  
                   str(time),
  
                   '-i',
  
                   video_url,
  
                   '-frames:v',
  
                   '1',
  
                   get_thumb_filename(i)])
  
          i += 1
  
      print(filenames_list)
  
      return filenames_list
  
  
  
  
  
  def s3_upload_file(file_path, key, bucket, acl, content_type):
  
      file = open(file_path, 'r')
  
      s3.put_object(
  
          Bucket=bucket,
  
          ACL=acl,
  
          Body=file,
  
          Key=key,
  
          ContentType=content_type
  
      )
  
      logger.info("file {0} moved to {1}/{2}".format(file_path, bucket, key))
  
  
  
  
  
  def s3_upload_files_in_threads(filenames_list, dir_path, bucket, s3path, acl, content_type):
  
      for filename in filenames_list:
  
          if os.path.isfile(os.path.join(dir_path, filename)):
  
              print(os.path.join(dir_path, filename))
  
          t = threading.Thread(target=s3_upload_file,
  
                               args=(os.path.join(dir_path, filename),
  
                                     '{0}/{1}'.format(s3path, filename),
  
                                     bucket,
  
                                     acl,
  
                                     content_type)).start()
  
  
  
  
  
  def lambda_handler(event, context):
  
      bucket = event['Records'][0]['s3']['bucket']['name']
  
      video_key = event['Records'][0]['s3']['object']['key']
  
      video_name = video_key.split('/')[-1].split('.')[0]
  
      video_url = 'http://{0}/{1}'.format(bucket, video_key)
  
      filenames_list = create_thumbnails(video_url)
  
      s3_upload_files_in_threads(filenames_list,
  
                                 os.getcwd(),
  
                                 bucket,
  
                                 '{0}/{1}'.format(video_frames_path, video_name),
  
                                 'public-read',
  
                                 'image/jpeg')
  
      return

  during the execution I get following logs :

  Loading function
  
  
  
  /tmp/ffmpeg.linux64
  
  
  
  ok
  
  
  
  [Errno 2] No such file or directory: OSError
  
  Traceback (most recent call last):
  
   File "/var/task/lambda_function.py", line 112, in lambda_handler
  
   filenames_list = create_thumbnails(video_url)
  
   File "/var/task/lambda_function.py", line 77, in create_thumbnails
  
   get_thumb_filename(i)])
  
   File "/usr/lib64/python2.7/subprocess.py", line 522, in call
  
   return Popen(*popenargs, **kwargs).wait()
  
   File "/usr/lib64/python2.7/subprocess.py", line 710, in __init__
  
   errread, errwrite)
  
   File "/usr/lib64/python2.7/subprocess.py", line 1335, in _execute_child
  
   raise child_exception
  
  OSError: [Errno 2] No such file or directory

  When I use the same sp.call() with the same ffmpeg binary on my ec2 instance it works fine.

• Concatenate chunk containg headers to another chunk in h264

  18 novembre 2014, par Ortixx

  I’m trying to extract thumbnails from a torrent stream by downloading the first couple of chunks to get the headers, another set of chunks from the middle and then concat them to have a single video file.

  For this I’m using nodejs but I’m having trouble with the concatenation part. Obviously the headers include the length of the video so if I simply concat another chunk to the end of the headers chunk, it won’t work.

  In other words, I have 2 chunks of a video file : The first one contains the headers and some material and the other one is fully composed of a video stream. I want to combine the two to form a single video file
  So my question is how can I make this work properly if at all ?