SPC (file format)

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SPC (also called SPC700 audio file ) is a video game music file format . This contains copies of melodies and music data as they are used in the RAM of the SPC700 sound chip , which was used in the Super Nintendo Entertainment System (SNES) game console . Alternatively, the data can also be processed by a console emulator such as ZSNES or Snes9x .

technology

The SPC700 chip (or its emulator) generates the sound by calling an embedded program that processes the stored music data and converts it into a sequence of DSP commands sent to the chip . This in turn generates the sound output according to the DSP commands. The possibilities of the SPC700-DSP commands allow music synthesis by samples (analogous to music playback by MOD or IT ) and extensive sound playback, which was only generated from 64 KB of data - while storage as an uncompressed WAVE file (when using PCM or similar) would require large amounts of data, with certain longer pieces up to hundreds of megabytes. The SPC700 chip produces a 16-bit output signal at 32 kHz, but SPC700 emulators can be configured to output a different sample rate (from eight to 48 kHz). The positions within a song are indicated by tics . This makes it possible to repeat certain areas and play them in a loop.

use

SPC plug-ins are available for Winamp , foobar2000 , Audacious , Rockbox (for portable MP3 players) and other popular players, some of which already have native SPC support. Some SPC players can even produce a higher output quality than the SPC700 chip itself by outputting the sound with a higher sampling rate (up to 192 kHz), using more complex sound interpolation methods and a special "high quality" optimization, how they use SNESAmp, for example. There are also programs such as SPC Tool or SPC2MIDI that are able to generate MIDI files from SPC files .

Soundtracks are now compressed with the RAR algorithm, using a progressive compression that is not available with ZIP compression. This archive format saves a lot of space, since a large number of the samples are usually reused within the songs and these only have to be saved instead of always being saved from scratch. The archived files have the extension RSN and are unzipped by the player when they are played.

restrictions

An inadequacy of the SPC format can be observed in the games Tales of Phantasia and Star Ocean . These games use "streaming sampling" which means that samples are exchanged during runtime in order to bypass the 64 KB limit of the SPC700 and thus to be able to use additional instruments and voices. However, since the dump only captures the samples that are loaded at the beginning of the game, this inevitably leads to incorrect samples being used for some songs. The music is played back accordingly distorted.

Plug-ins and players

  • Audacious , a media player for Windows / Linux that supports SPC files.
  • Audio Overload , a Windows / Mac / Linux player especially for video game music that supports SPC files among many others.
  • Chipamp , one of OverClocked ReMix initiated Winamp - plug-in for playback of over 40 Chiptune- and Tracker formats.
  • VLC media player , a player for Windows / Mac / Linux that plays back SPC files in addition to many other formats.

See also

Web links