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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.

• how to choose ffmpeg video mp3 audio version id ?

  7 juin 2013, par Ulterior

  I am having issues on ffmpeg encoded video files audio tracks. My encoded video contains ID for audio track as extracted from mediainfo :

  I use CODEC_ID_MP3 in guess_format "mov" container for quicktime

  Audio
  
  ID                                       : 2
  
  Format                                   : MPEG Audio
  
  Format version                           : Version 2
  
  Format profile                           : Layer 3
  
  Codec ID                                 : .mp3
  
  Duration                                 : 2s 916ms
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 128 Kbps
  
  Channel(s)                               : 1 channel
  
  Sampling rate                            : 16.0 KHz
  
  Compression mode                         : Lossy
  
  Stream size                              : 45.3 KiB (2%)
  
  Language                                 : English

  This is not recognized on a vanilla codecless installation of windows 7, only played by k-lite codec libmad

  I have noticed, that another test file contains similar mp3 track and is played by media player OK :

  Audio
  
  ID                                       : 2
  
  Format                                   : MPEG Audio
  
  Format version                           : Version 1
  
  Format profile                           : Layer 3
  
  Mode                                     : Joint stereo
  
  Mode extension                           : MS Stereo
  
  Codec ID                                 : 6B
  
  Duration                                 : 1mn 9s
  
  Bit rate mode                            : Constant
  
  Bit rate                                 : 320 Kbps
  
  Channel(s)                               : 2 channels
  
  Sampling rate                            : 44.1 KHz
  
  Compression mode                         : Lossy
  
  Stream size                              : 2.67 MiB (38%)
  
  Writing library                          : LAME3.98

  The difference I noticed is in Format version number and Codec ID, which is Version 2 from ffmpeg output - I couldnt locate this version setting in ffmpeg source files, so my question is - is there a way to influence this format version identificator and set the codec id as in above playable video ?

• Centos7 Server, Masrer Playlist can't create CODECS when use ffmpeg with libx265 (h.265)

  8 juillet 2020, par Duy Đức Nguyễn Phạm

  I use ffmpeg to stream from a link, when I use libx264 it run very good but when I use libx265, file master playlist can't create CODECS

  


  #ffmpeg

ffmpeg version N-98423-g584f396 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-39)
  configuration: --prefix=/./usr/local/ffmpeg --bindir=/./usr/local/bin/ --pkg-config-flags=--static --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --extra-libs=-lpthread --extra-libs=-lm --bindir=/root/bin --enable-gpl --enable-libfdk_aac --enable-libfreetype --enable-libopus --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree
  libavutil      56. 55.100 / 56. 55.100
  libavcodec     58. 94.100 / 58. 94.100
  libavformat    58. 48.100 / 58. 48.100
  libavdevice    58. 11.101 / 58. 11.101
  libavfilter     7. 86.100 /  7. 86.100
  libswscale      5.  8.100 /  5.  8.100
  libswresample   3.  8.100 /  3.  8.100
  libpostproc    55.  8.100 / 55.  8.100


  


  I check output video by command

  


  #ffprobe -v error -select_streams v:0 -show_entries stream=codec_name   -of default=noprint_wrappers=1:nokey=1 v0_s.m3u8


  


  Then the screen show

  


  hevc
hevc


  


  And this is master playlist comparison example when I use x265 (v0) and x264 (v1)

  


  #EXTM3U
#EXT-X-VERSION:7
#EXT-X-STREAM-INF:BANDWIDTH=401500,RESOLUTION=640x480
v0/prog_index.m3u8

#EXT-X-STREAM-INF:BANDWIDTH=2200000,RESOLUTION=1280x720,CODECS="avc1.42c01f"
v1/prog_index.m3u8


  


  Sorry about my English.
Can you help me ? Thank you !