参照：http://www.keyfc.net/bbs/showtopic-8664.aspx
REALLIVE系列引擎中BGM(*.NWA)文件的提取方法
正常状态下NWA文件是带有特殊头信息的PCM格式
一种解法是直接放入音频编辑软件，去除开头杂音后保存
另一种是foobar2000安装插件foo_adpcm直接读取.
http://kode54.foobar2000.org/
http://kode54.foobar2000.org/?v
foo_adpcm
144.1 KB
2013-08-13 03:04:24
Supports CRI ADX, my own BRR format based on Sony SPC-700 and PSX ADPCM, everything from in_cube (DSP, GCM, HPS, IDSP, SPT/SPD, MSS, ADP), EA MUS/ASF and MAP files, a host of formats from foo_okiapcm/libpcm (Circus-XPCM sample files (and also ADPCM files from the Saturn version of Symphony of the Night / Dracula X: Nocturne in the Moonlight) (.PCM), Konami-Gungage-XA sample files (.8), KID-WAF sample files (.WAF), BasiL-WPD sample files (.WPD), TamaSoft-MPF sample files (.MPF), StudioMiris-WDT sample files (.WDT), Hayashigumi-KWF sample files (.KWF), VisualArts-NWA sample files (.NWA), jANIS-PX sample files (.PX), CLOVER-BW sample files (.BW)), RAC IMA-ADPCM files from Star Trek: The Next Generation – A Final Unity PC game, and XA ADPCM files from various games. Whew.