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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.