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11 September 2026

Converting Atari ST Audio Visual Research Audio (.AVR) to Linear PCM WAV

Throughout the late 1980s and 1990s, the Atari ST was revered as the digital audio workstation of choice across recording studios worldwide. Thanks to built-in 5-pin DIN MIDI in/out ports, precise hardware timing from the Motorola 68000 processor, and software pioneers like Steinberg (Cubase) and C-Lab (Notator), the Atari ST and later Falcon030 shaped the sound of early electronic, techno, and industrial music.

To support digital sound sampling, hard-disk recording, and sample playback on the ST, British developer Audio Visual Research designed the AVR (.avr) digital audio container.

Vintage sample CDs, Atari demoscene releases, and sound banks frequently contain .avr instrument files. This guide details how the 128-byte AVR header is constructed, how sample signedness and bit depths are stored, and how to convert .avr files directly into universal 16-bit linear PCM WAVs in your browser using convrtr's Atari ST AVR to WAV converter.

Forensic Structure of the 128-Byte 2VRH Header

Unlike raw headerless sample dumps, AVR files begin with a fixed 128-byte metadata header. All multi-byte numeric fields are encoded in Motorola big-endian byte order:

| Offset (Bytes) | Field Name | Data Type | Description | | :--- | :--- | :--- | :--- | | 0x00 - 0x03 | Magic Bytes | 4 ASCII chars | Always "2VRH" (0x32 0x56 0x52 0x48) | | 0x04 - 0x0B | Sample Name | 8 ASCII chars | Null-padded sample title | | 0x0C - 0x0D | Channel Mode | 16-bit uint | 0x0000 = Mono, 0xFFFF = Stereo | | 0x0E - 0x0F | Resolution | 16-bit uint | 8 = 8-bit, 16 = 16-bit | | 0x10 - 0x11 | Format | 16-bit uint | 0x0000 = Unsigned, 0xFFFF = Signed | | 0x12 - 0x13 | Loop Mode | 16-bit uint | 0x0000 = No loop, 0xFFFF = Loop | | 0x14 - 0x15 | MIDI Note | 16-bit uint | MIDI root key (0x0000 = Not set) | | 0x16 - 0x19 | Sample Rate | 32-bit uint | Sampling frequency in Hz (e.g., 22050, 44100) | | 0x1A - 0x1D | Sample Count | 32-bit uint | Total number of sample frames in payload | | 0x1E - 0x21 | Loop Start | 32-bit uint | Loop start frame offset | | 0x22 - 0x25 | Loop End | 32-bit uint | Loop end frame offset | | 0x26 - 0x27 | Reserved | 2 bytes | Reserved padding | | 0x28 - 0x7F | User Comment | 88 ASCII chars | Null-padded descriptive notes or copyright | | 0x80 onwards| Audio Payload | Raw byte stream | 8-bit or 16-bit big-endian PCM sample frames |

Resolving Signed vs Unsigned Sample Values

A unique aspect of vintage digital audio formats is signedness flexibility:

  • 8-bit Unsigned: Bytes range from 0 to 255, where 128 represents digital zero. To convert to standard 16-bit signed PCM: Sample16 = (Byte - 128) * 256
  • 8-bit Signed: Bytes range from -128 to +127, where 0 is digital zero: Sample16 = Byte * 256
  • 16-bit Big-Endian: Read as 16-bit big-endian integers, clamped to the [-32768, 32767] range, and written as little-endian words into the target RIFF WAV container.

Decoding AVR in Modern Browsers

Because modern operating systems and web browsers lack native AVR decoders, convrtr performs zero-server client-side conversion:

  1. Validates the "2VRH" magic header.
  2. Extracts sample rate, channel count, and sample dimensions.
  3. Normalizes 8-bit and 16-bit big-endian samples into signed 16-bit little-endian PCM frames.
  4. Wraps decoded audio in a compliant 44-byte RIFF/WAVE header ready for immediate in-browser playback or export into Ableton Live, Logic Pro, and Audacity.