at3emu

at3tool CPU emulation via (Unicorn Engine) to run the original 32bit x86 Linux ELF binary.

Primarily built for macOS. Windows works as well, but is extremely slow: use at3tool.exe instead. Untested on Linux, but the native ELF binary should work natively as well.

# show original help
at3emu

# encode 16-bit 44.1kHz PCM WAV
# (LP2 = 132kbps, LP4 = 66kbps)
at3emu -e -br 132 song.wav song.at3

# decode
at3emu -d song.at3 song_decoded.wav

Download

Prebuilt binaries for are available on the Releases page.

1. Download the prebuilt binary

2. Place libatrac.so.1.2.0 and at3tool inside a linux folder next to the binary

   at3emu
   linux/
   ├── at3tool
   └── libatrac.so.1.2.0
   

3. Run the binary. See Usage below for all options.

Setup

1. Prerequisites

• Rust 1.96.0+ (rustup.rs)
• A C compiler — gcc/clang on macOS
• CMake (usually included with build tools; install via brew install cmake if missing)

2. Get the Sony binaries

You need two files from the PSP SDK (not included in this repo):

linux/
├── at3tool              # The CLI tool (28 KB, ELF 32-bit)
└── libatrac.so.1.2.0    # The codec library (1 MB, ELF 32-bit)

Place them in a linux/ directory next to the executable, or pass paths explicitly.

3. Build

git clone <this-repo>
cd at3tool-emu
cargo build --release

4. Run

# Auto-discovers binaries in ./linux/
./target/release/at3emu -e -br 132 input.wav output.at3

# Or specify paths explicitly
./target/release/at3emu --at3tool /path/to/at3tool --libatrac /path/to/libatrac.so.1.2.0 -e -br 132 song.wav song.at3

Usage

at3emu [-<option>] file1 file2

Options:
  -e                   Encode: PCM WAV → ATRAC3/ATRAC3plus
  -d                   Decode: ATRAC3/ATRAC3plus → PCM WAV
  -br N                Bitrate in kbps
  -loop S E            Loop start/end in samples
  -wholeloop           Loop the entire file
  -repeat N            Repeat loop N times during decode (default: 2)

Extra:
  --at3tool <path>     Path to at3tool binary
  --libatrac <path>    Path to libatrac.so.1.2.0
  --list-codecs        Show all supported bitrate/channel combinations

Supported Bitrates

Codec	Bitrates	Channels
ATRAC3	52	Mono
ATRAC3	66	Mono, Stereo
ATRAC3	105, 132	Stereo
ATRAC3plus	32, 48, 64, 96, 128	Mono
ATRAC3plus	48, 64, 96, 128, 160, 192, 256, 320, 352	Stereo

Input WAV must be 16-bit linear PCM, 44100 Hz.

Verification

Output is verified byte-for-byte against the real at3tool running in Docker:

Test	Result
Encode 66kbps (small file)	Byte-for-byte identical
Encode 66kbps (4-min song)	Valid AT3, imperceptible audio difference
Encode 132kbps LP2	Valid AT3, imperceptible audio difference
Decode (any AT3 input)	Byte-for-byte identical to real at3tool
Null test (original − decoded)	Near silence

Performance is ~1.17x slower than the native binary (2m17s vs 1m57s for a 4-minute song on Apple M2).

License

This project is MIT licensed. The Sony at3tool and libatrac.so binaries are SCE Confidential and must be obtained separately through proper PSP SDK licensing channels. This emulator does not include or distribute them.

TODO

• expose nicer core API (right now it's a bit messy to set up everything)