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--- title: XA (CD-ROM Voice Data) type: format summary: ADPCM audio data in the CD-ROM XA format. category: File formats info: Extension = .XA info: Created by = RAW2XA --- ## Overview XA is the PlayStation CD-ROM XA voice data format, and its typical extension in DOS is ".XA". The format is based on the CD-ROM XA System Description of May 1991, and the XA file output by RAW2XA has a sub-header.[^ff131] The PlayStation plays back ADPCM audio data as specified in the CD-ROM XA (eXtended Audio) standard, which Sony calls XA-ADPCM audio. XA-ADPCM audio is sent directly from the CD-ROM decoder to the SPU without using main memory. Four types are supported:[^ff16] Table: XA-ADPCM audio data types supported by PlayStation | Sampling frequency | Stereo/monaural | | --- | --- | | 37.8 kHz | Stereo | | 37.8 kHz | Monaural | | 18.9 kHz | Stereo | | 18.9 kHz | Monaural | ## Interleave When XA-ADPCM audio is played back, its sectors must be interleaved with gap sectors on the CD-ROM. The ratio of data sectors to gap size depends on the type of audio and on the playback speed of the CD-ROM. In the table below a lower sampling frequency or a monaural sound therefore takes one audio sector in a longer run of sectors.[^ff16][^ff17] Table: Data/gap ratios | CD-ROM playback speed | Type | Data/gap ratio | | --- | --- | --- | | Double speed | 37.8 kHz, stereo | 1 sector/7 sectors | | Double speed | 37.8 kHz, monaural | 1 sector/15 sectors | | Double speed | 18.9 kHz, stereo | 1 sector/15 sectors | | Double speed | 18.9 kHz, monaural | 1 sector/31 sectors | | Standard speed | 37.8 kHz, stereo | 1 sector/3 sectors | | Standard speed | 37.8 kHz, monaural | 1 sector/7 sectors | | Standard speed | 18.9 kHz, stereo | 1 sector/7 sectors | | Standard speed | 18.9 kHz, monaural | 1 sector/15 sectors | [STR](/formats/str/) streaming data with audio places movie data in the gap sectors.[^ff17] ## References [^ff16]: Sony Computer Entertainment Inc. File Formats. November 1998. Page 1-6, Table 1-1. [^ff17]: Sony Computer Entertainment Inc. File Formats. November 1998. Page 1-7, Table 1-2. [^ff131]: Sony Computer Entertainment Inc. File Formats. November 1998. Page 1-31.