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• Launch Leech and the History of WMV

  14 septembre 2010, par Multimedia Mike — General

  I was combing through my programming archives again and came across an old Perl script called launch-leech.pl. This was a private script I used to maintain for the benefit of myself and a few friends. See, there was this site called Launch.com (URL doesn’t seem to do anything as of this writing but here’s the Wikipedia page). Purchased by Yahoo ! in 2001, Launch still maintained their independent branding. They also carried a lot of music videos, of which I am a huge junkie. launch-leech.pl was the tool I used to download the videos. This was particularly useful since I stubbornly clung to dialup internet access until mid-2004 and it would have been impossible to stream video at any decent quality (though there were 56k streams, so like I said– not possible at any decent quality).

  
  
  

  Technically
  I followed Launch.com for many years. To be honest, I only “followed” in that I figured out where their “latest videos” URL lived and regularly polled it. Each video had either a 6-, 7-, or 8-digit unique ID that could be plugged into the launch-leech.pl script which would then have a conversation with the relevant servers, determine the correct streaming URL with the highest quality, then download and save the URL by handing it off to an external program (first ASFRecorder, though I later switched to mmsclient).

  At one point, I even wrote a crawler that compiled an offline database of all the videos, their IDs and their metadata. I never thought of anything interesting to do with it, though.

  
  
  

  Windows Media Legacy
  During these glory days of leeching, Launch.com streamed using Windows Media. I admit, it’s a bit of a blur now — the site might have used Real or QuickTime, but I was obviously most in tune with the WM side. I remember when I first found the site circa 2000-2001, the videos were in MS MPEG-4v3, and the high quality bitrate was 300 kbits/sec. Eventually, Launch.com would stream WMV7, WMV8, and finally WMV9, with bitrates up to 700 kbits/sec. However, they never broke free of the 320×240 encoding resolution, which was frustrating. When I wasn’t able to notice any substantial difference between 300 and 700 kbits/sec, I felt it might be time to put those extra bits to work on a resolution upgrade.

  At least they were nice enough to re-encode a number of old videos using better codecs and bitrates with each revision, thus prompting me to scan through the site collecting updated video IDs for download.

  
  
  

  Epilogue
  I don’t clearly remember when I stopped visiting Launch.com. Video-wise, the web has been a blur of Flash video ever since about 2006. Meanwhile, I spent a lot of time collecting a bunch of music videos in the first half of the decade only to find that pretty much every version of every music video made since the dawn of time is available on demand thanks to YouTube. I have found that this phenomenon manifests in many areas as internet technology marches on.

  The Real Entertainment
  The launch-leech.pl tool represents a recurring pattern for me. I derive as much — if not more — entertainment from creating programs like launch-leech.pl (and implicitly reverse engineering something in the process ; in this case, a website) as I do from the intended entertainment media itself. I seem to have this issue a lot with games, too.

  Is this an issue for anyone else ? Am I the only one who would rather play with the box that a shiny toy comes packaged in ?

• simple_idct : x86 : Drop disabled IDCT implementation

  1er août 2016, par Diego Biurrun

  simple_idct : x86 : Drop disabled IDCT implementation
  This gem has been disabled since 2001.
  

  • [DBH] libavcodec/x86/simple_idct.c

• dashjs can't find initialization segment on manifest.mpd

  30 avril 2016, par Abelardo Mendoza

  I am following this tutorial to stream a WebM. I have no issues running the ffmpeg commands to generate the videos/audio/manifest files but when I try to run it locally, there’s no video or audio at all and dashjs floods the console with :

  Searching for initialization.    
  
  Start searching for initialization.     
  
  Perform init search: http://localhost:8080/video_1280x720_500k.webm    
  
  Perform SIDX load: http://localhost:8080/video_640x360_750k.webm     
  
  Perform SIDX load: http://localhost:8080/video_1280x720_500k.webm 

  Writing that to console until I stop the server. I have tried using other mpd files such as this, which is used on the dashjs quickstart and it plays the video without any problems.

  I used this guide to install the latest version of ffmpeg on Ubuntu 14.04 LTS :

  ffmpeg version N-79688-g3cb3ddd Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 5.3.0 (Ubuntu 5.3.0-3ubuntu1~14.04) 20151204
  
  configuration: --prefix=/home/ab/cpp/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/home/ab/cpp/ffmpeg_build/include --extra-ldflags=-L/home/ab/cpp/ffmpeg/lib --bindir=/home/ab/bin --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
  
  libavutil      55. 23.100 / 55. 23.100
  
  libavcodec     57. 38.100 / 57. 38.100
  
  libavformat    57. 34.103 / 57. 34.103
  
  libavdevice    57.  0.101 / 57.  0.101
  
  libavfilter     6. 44.100 /  6. 44.100
  
  libswscale      4.  1.100 /  4.  1.100
  
  libswresample   2.  0.101 /  2.  0.101
  
  libpostproc    54.  0.100 / 54.  0.100

  When running on ffmpeg :

  ffmpeg \
  
   -f webm_dash_manifest -i video_160x90_250k.webm \
  
   -f webm_dash_manifest -i video_320x180_500k.webm \
  
   -f webm_dash_manifest -i video_640x360_750k.webm \
  
   -f webm_dash_manifest -i video_640x360_1000k.webm \
  
   -f webm_dash_manifest -i video_1280x720_500k.webm \
  
   -f webm_dash_manifest -i audio_128k.webm \
  
   -c copy -map 0 -map 1 -map 2 -map 3 -map 4 -map 5 \
  
   -f webm_dash_manifest \
  
   -adaptation_sets "id=0,streams=0,1,2,3,4 id=1,streams=5" \
  
   manifest.mpd

  It generates the following manifest.mpd :

  <?xml version="1.0" encoding="UTF-8"?>
  
  <mpd xmlns="urn:mpeg:DASH:schema:MPD:2011" type="static" mediapresentationduration="PT117.726S" minbuffertime="PT1S" profiles="urn:webm:dash:profile:webm-on-demand:2012">
  
    <period start="PT0S" duration="PT117.726S">
  
      <adaptationset mimetype="video/webm" codecs="vp9" lang="eng" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">
  
        <representation bandwidth="198155" width="160" height="90">
  
          <baseurl>video_160x90_250k.webm</baseurl>
  
          <segmentbase indexrange="2007834-2008211">
  
            <initialization range="0-437"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="459264" width="320" height="180">
  
          <baseurl>video_320x180_500k.webm</baseurl>
  
          <segmentbase indexrange="4459996-4460374">
  
            <initialization range="0-439"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="718495" width="640" height="360">
  
          <baseurl>video_640x360_750k.webm</baseurl>
  
          <segmentbase indexrange="6614036-6614414">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="931445" width="640" height="360">
  
          <baseurl>video_640x360_1000k.webm</baseurl>
  
          <segmentbase indexrange="8309082-8309460">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
        <representation bandwidth="821274" width="1280" height="720">
  
          <baseurl>video_1280x720_500k.webm</baseurl>
  
          <segmentbase indexrange="8728812-8729190">
  
            <initialization range="0-441"></initialization>
  
          </segmentbase>
  
        </representation>
  
      </adaptationset>
  
      <adaptationset mimetype="audio/webm" codecs="vorbis" lang="eng" audiosamplingrate="44100" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">
  
        <representation bandwidth="107104">
  
          <baseurl>audio_128k.webm</baseurl>
  
          <segmentbase indexrange="1538710-1539184">
  
            <initialization range="0-4112"></initialization>
  
          </segmentbase>
  
        </representation>
  
      </adaptationset>
  
    </period>
  
  </mpd>

  The index.html has a few changes because dash.js changed the way the player gets initialized.

      
  
          
  
          
  
          <code class="echappe-js">&lt;script src=&quot;http://cdn.dashjs.org/latest/dash.all.debug.js&quot;&gt;&lt;/script&gt;
  
              
          
  

  And here is Chromium’s log file. I’m converting this webm from this site.

  If I missed out any other relevant information or if anyone can guide me into the right direction, please let me know.

  Edit :

  Like Will Law mentioned, using the Shaka Player worked without any issues with my current manifest. Hope this helps anyone else.