Recherche avancée

Sur d’autres sites (5720)

• 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.

• Concat two mp4 files with MP4Box error : Bad Parameter [on hold]

  6 février 2014, par user3279646

  I'm trying to concat two mp4 files. But I get an error : Bad Parameter

  Can someone help me with this problem ?

  I'm using de debian packages. On a previously version it worked fine. I moved from a old debian version to the new one and I also had to change the ffmpeg to avconv which I use to create these mp4 files. I also had to change the audio codec to '-acodec aac -strict experimental'

  Kind Regards,
  Marcel

      MP4Box -force-cat -cat conv1-1391608417314.mp4 -add conv1-1391608417345.mp4 -new output.mp4
  
      IsoMedia import - track ID 1 - Video (size 384 x 288)
  
      Error importing conv1-1391608417345.mp4: Bad Parameter

  ---

      MP4Box -info conv1-1391608417314.mp4
  
      Movie Info 
  
      Timescale 1000 - Duration 00:00:23.985
  
      Fragmented File no - 2 track(s)
  
      File Brand isom - version 512
  
      Created: UNKNOWN DATE
  
      File has root IOD (9 bytes)
  
      Scene PL 0xff - Graphics PL 0xff - OD PL 0xff
  
      Visual PL: Not part of MPEG-4 Visual profiles (0xfe)
  
      Audio PL: Not part of MPEG-4 audio profiles (0xfe)
  
      No streams included in root OD
  
  
  
      iTunes Info:
  
      Encoder Software: Lavf53.21.1
  
  
  
      Track # 1 Info - TrackID 1 - TimeScale 1000 - Duration 00:00:23.985
  
      Media Info: Language "Undetermined" - Type "vide:avc1" - 23988 samples
  
      Visual Track layout: x=0 y=0 width=384 height=288
  
      MPEG-4 Config: Visual Stream - ObjectTypeIndication 0x21
  
      AVC/H264 Video - Visual Size 384 x 288
  
      AVC Info: 1 SPS - 1 PPS - Profile High @ Level 4.2
  
      NAL Unit length bits: 32
  
      Self-synchronized
  
  
  
      Track # 2 Info - TrackID 2 - TimeScale 44100 - Duration 00:00:23.962
  
      Media Info: Language "Undetermined" - Type "soun:mp4a" - 1032 samples
  
      MPEG-4 Config: Audio Stream - ObjectTypeIndication 0x40
  
      MPEG-4 Audio MPEG-4 Audio AAC LC - 2 Channel(s) - SampleRate 44100
  
      Synchronized on stream 1
  
      Alternate Group ID 1

  ---

      MP4Box -version
  
      MP4Box - GPAC version 0.5.0-rev
  
      GPAC Copyright: (c) Jean Le Feuvre 2000-2005
  
      (c) ENST 2005-200X
  
      GPAC Configuration: --build=x86_64-linux-gnu --prefix=/usr --includedir=${prefix}/include --mandir=${prefix}/share/man --infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var --libdir=${prefix}/lib/x86_64-linux-gnu --libexecdir=${prefix}/lib/x86_64-linux-gnu --disable-maintainer-mode --disable-dependency-tracking --prefix=/usr --mandir=${prefix}/share/man --libdir=lib/x86_64-linux-gnu --extra-cflags='-Wall -fPIC -DPIC -I/usr/include/mozjs -DXP_UNIX' --enable-joystick --enable-debug --disable-ssl
  
      Features: GPAC_HAS_JPEG GPAC_HAS_PNG

• OS X uploads .mp4 as quicktime ? [on hold]

  15 janvier 2014, par daled

  I'm running into a rather peculiar issue uploading .mp4 from any browser on OS X. I'm using ffmpeg to convert files and .mp4's uploaded from OS X are causing issues.

  First off, the file I'm uploading is not corrupt. Here is the relevant exiftool output on the file I'm uploading. This is the original file on the client.

  File Type                       : MP4
  
  MIME Type                       : video/mp4
  
  Major Brand                     : MP4 Base w/ AVC ext [ISO 14496-12:2005]
  
  Minor Version                   : 0.0.0
  
  Compatible Brands               : avc1, isom

  Now here's the exiftool output on the server for the same file :

  File Type                       : MOV
  
  MIME Type                       : video/quicktime
  
  Major Brand                     : Apple QuickTime (.MOV/QT)
  
  Minor Version                   : 2005.3.0
  
  Compatible Brands               : qt

  Ffmpeg will recognize the first file just fine. Everything will work perfectly and I can convert it however I choose. But the second file, I'll get this error :

  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x3855180] stream 0, error opening alias: path='/Users/', dir='20130602-113438', filename='GOPR0018.MP4', volume='Macintosh HD', nlvl_from=-1, nlvl_to=-1
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x3855180] stream 1, error opening alias: path='/Users/', dir='20130602-113438', filename='GOPR0018.MP4', volume='Macintosh HD', nlvl_from=-1, nlvl_to=-1

  Here is the FFmpeg command I am using :

  ffmpeg -y -probesize 2147483647 -analyzeduration 2147483647 -i "'.$oldFilename.'" -vcodec libtheora -q:v 0 -acodec libvorbis -q:a 0 "'.$newFilenameOGG.'" 2>&1

  This command works fine with every file type besides this file. It seems like ffmpeg is seeing the uploaded file as a corrupt quicktime file instead of a valid mp4 file. So my question is, how is this metadata magically changing ?