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• Adding AY Files To The Game Music Website

  1er décembre 2013, par Multimedia Mike — General

  For the first time since I launched the site in the summer of last year, I finally added support for new systems for my Game Music Appreciation site : A set of chiptune music files which bear the file extension AY. These files come from games that were on the ZX Spectrum and Amstrad CPC computer systems.

  
   
  

  Right now, there are over 650 ZX Spectrum games in the site while there are all of 20 Amstrad CPC games. The latter system seems a bit short-changed, but I read that a lot of Amstrad games were straight ports from the Spectrum anyway since the systems possessed assorted similarities. This might help explain the discrepancy.

  Technically
  The AY corpus has always been low hanging fruit due to the fact that the site already supports the format courtesy of the game-music-emu backend. The thing that blocked me was that I didn’t know much about these systems. I knew that there were 2 systems (and possibly more) that shared the same chiptune format. Apparently, these machines were big in Europe (I was only vaguely aware of them before I started this project).

  Both the Spectrum and the Amstrad used Zilog Z-80 CPUs for computing and created music using a General Instruments synthesizer chip designated AY-3-8912, hence the chiptune file extension AY. This has 3 channels similar to the C64 SID chip. Additionally, there’s a fourth channel that game music emu calls “beeper” (and which Wikipedia describes as “one channel with 10 octaves”). Per my listening, it seems similar to the old PC speaker/honker. The metadata for a lot of the songs will specify either (AY) or (Beeper).

  Wrangling Metadata
  Large collections of AY files are easy to find ; as is typical for pure chiptunes, the files are incredibly small.

  As usual, the hardest part of the whole process was munging metadata. There seems to be 2 slightly different conventions for AY metadata, likely from 2 different people doing the bulk of the work and releasing the fruits of their labor into the wild. After I recognized the subtle differences between the 2 formats, it was straightforward to craft a tool to perform most of the work, leaving only a minimum of cleanup effort required afterwards.

  (As an aside, I think this process is called extract – transform – load, or ETL. Sounds fancy and complicated, yet it’s technically one of the first computer programming tasks I was ever paid to perform.)

  Collateral Damage
  While pushing this feature, I managed to break the site’s search engine. The search solution I developed was always sketchy (involving compiling a C program as a static binary CGI script and trusting it to run on the server). I will probably need to find a better approach, preferably sooner than later.

• mov : Pick up "com.apple.quicktime.artwork" as cover art

  1er avril 2021, par Martin Storsjö

  mov : Pick up "com.apple.quicktime.artwork" as cover art
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/mov.c

• WebM file not seekable in Chrome when loaded through PHP (other browsers work)

  13 avril 2014, par Zoon

  I am having a mind-boggling problem, I just can't seem to resolve.

  Providing a WebM file through PHP is nothing new in my world, and I even know how to work with HTTP 206 Partial Content. But for some reason Chrome does not like it.

  A simple HTML5 video playback

  <video width="640" height="360" poster="picture/preview/V00000006.jpg" controls="controls" preload="preload">
  
      <source type="video/webm" src="/video/V00000006.webm">
  
  </source></video>

  where /video/V00000006.webm is rewritten to a PHP-file in Apache, will playback just fine.
  But in Chrome the seekbar is not effective. When clicking on the seekbar the player will freeze and no longer playback until page is refreshed. Firefox handles it just fine !

  If I change /video/V00000006.webm to be a direct link to the same video it works just fine. I even compared the network requests between the two versions (with and without PHP) and there is barely any difference in the first request, but the second is failing in the PHP-delivered video.

  Initial request and seek request for Apache-delivered video file :

      Request URL :http://mytestserver.net/movie1152x720.webm
      Request Method:GET
      Status Code:206 Partial Content
      Request Headers
      Accept :*/*
      Accept-Encoding:identity ;q=1, * ;q=0
      Accept-Language:da-DK,da ;q=0.8,en-US ;q=0.6,en ;q=0.4
      Cache-Control:no-cache
      Connection:keep-alive
      Cookie:PHPSESSID=i562540rek172mnv3nk528acj0 ; userPassword= ; userEmail=
      Host:mytestserver.net
      Pragma:no-cache
      Range:bytes=0-
      Referer :http://mytestserver.net/video.html
      User-Agent:Mozilla/5.0 (X11 ; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36
      Response Headers
      Accept-Ranges:bytes
      Connection:close
      Content-Length:4446451
      Content-Range:bytes 0-4446450/4446451
      Content-Type:video/webm
      Date:Fri, 11 Apr 2014 13:07:30 GMT
      ETag :"d2d0027-43d8f3-b91417c0"
      Last-Modified:Fri, 11 Apr 2014 12:46:31 GMT
      Server:Apache/2.2.3 (CentOS)
      —
      Request URL :http://mytestserver.net/movie1152x720.webm
  
      Request Method:GET
  
      Status Code:206 Partial Content
  
      Request Headers
  
      Accept :*/*
  
      Accept-Encoding:identity ;q=1, * ;q=0
  
      Accept-Language:da-DK,da ;q=0.8,en-US ;q=0.6,en ;q=0.4
  
      Cache-Control:no-cache
  
      Connection:keep-alive
  
      Cookie:PHPSESSID=i562540rek172mnv3nk528acj0 ; userPassword= ; userEmail=
  
      Host:mytestserver.net
  
      Pragma:no-cache
  
      Range:bytes=4445881-
  
      Referer :http://mytestserver.net/video.html
  
      User-Agent:Mozilla/5.0 (X11 ; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36
  
      Response Headers
  
      Accept-Ranges:bytes
  
      Connection:close
  
      Content-Length:570
  
      Content-Range:bytes 4445881-4446450/4446451
  
      Content-Type:video/webm
  
      Date:Fri, 11 Apr 2014 13:09:02 GMT
  
      ETag :"d2d0027-43d8f3-b91417c0"
  
      Last-Modified:Fri, 11 Apr 2014 12:46:31 GMT
  
      Server:Apache/2.2.3 (CentOS)
  

  Initial request and seek request for PHP-streamed video :

      Request URL :http://mytestserver.net/video/V00000006.webm
      Request Method:GET
      Status Code:206 Partial Content
      Request Headers
      Accept :*/*
      Accept-Encoding:identity ;q=1, * ;q=0
      Accept-Language:da-DK,da ;q=0.8,en-US ;q=0.6,en ;q=0.4
      Cache-Control:no-cache
      Connection:keep-alive
      Cookie:PHPSESSID=i562540rek172mnv3nk528acj0 ; userPassword= ; userEmail=
      Host:mytestserver.net
      Pragma:no-cache
      Range:bytes=0-
      Referer :http://mytestserver.net/video.html
      User-Agent:Mozilla/5.0 (X11 ; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36
      Response Headers
      Accept-Ranges:bytes
      Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
      Connection:close
      Content-Length:8566268
      Content-Range:bytes 0-8566267/8566268
      Content-Type:video/webm
      Date:Fri, 11 Apr 2014 13:31:27 GMT
      Expires:Thu, 19 Nov 1981 08:52:00 GMT
      Pragma:no-cache
      Server:Apache/2.2.3 (CentOS)
      X-Powered-By:PHP/5.3.27
      —
      Request URL :http://mytestserver.net/video/V00000006.webm
  
      Request Headers CAUTION : Provisional headers are shown.
  
      Accept-Encoding:identity ;q=1, * ;q=0
  
      Cache-Control:no-cache
  
      Pragma:no-cache
  
      Range:bytes=4338314-
  
      Referer :http://mytestserver.net/video.html
  
      User-Agent:Mozilla/5.0 (X11 ; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/33.0.1750.146 Safari/537.36
  

  Notice how the second request does not complete, Provisional headers are shown.

  I have tried altering the cache headers, setting it to the future, setting them blank and using file attachment headers.

  I tried fiddling around a lot with the serving code, but lately I have ended up with a simple example.

  <?php
  
  
  
  $path = 'test.webm';
  
  
  
  $size=filesize($path);
  
  
  
  $fm=@fopen($path,'rb');
  
  if(!$fm) {
  
    header ("HTTP/1.0 404 Not Found");
  
    die();
  
  }
  
  
  
  $begin=0;
  
  $end = $size-1;
  
  
  
  if(isset($_SERVER['HTTP_RANGE'])) {
  
    if(preg_match('/bytes=\h*(\d+)-(\d*)[\D.*]?/i', $_SERVER['HTTP_RANGE'], $matches)) {
  
      $begin=intval($matches[0]);
  
      if(!empty($matches[1])) {
  
        $end=intval($matches[1]);
  
      }
  
    }
  
  }
  
  
  
  if($begin>0||$end<$size)
  
    header('HTTP/1.0 206 Partial Content');
  
  else
  
    header('HTTP/1.0 200 OK');
  
  
  
  header("Content-Type: video/webm");
  
  header('Accept-Ranges: bytes');
  
  header('Content-Length:'.($end-$begin+1));
  
  header("Content-Disposition: inline;");
  
  header("Content-Range: bytes $begin-$end/$size");
  
  header("Content-Transfer-Encoding: binary\n");
  
  header('Connection: close');
  
  
  
  ob_get_clean();
  
  flush();
  
  
  
  $f = fopen($path, 'r');
  
  fseek($f, $offset);
  
  
  
  $pos = 0;
  
  $length = $end-$begin;
  
  
  
  while($pos < $length)
  
  {
  
      $chunk = min($length-$pos, 1024);
  
  
  
      echo fread($f, $chunk);
  
      flush();
  
  
  
      $pos += $chunk;
  
  }
  
  ?>

  Please note, entering the PHP-delivered video URL directly into the browser does not make a difference from showing it in a HTML page.

  I hope someone has an answer to why seeking might not work. Let me know if you have any suggestions.

  Thanks !