RAU Retro Audio
RAU compresses audio with a simple integer decoder. Designed for small engines, games and retro projects, it offers lossless compression or deliberately reduced quality without an external audio codec.
A little technical detail
Mono or stereo, 8 or 16 bits. Frames of up to 1,024 samples per channel use linear prediction, stereo decorrelation and Rice codes. RA26 holds one stream; RC26 groups independent packets. Lossless preserves the samples and sample rate. Mid reduces the rate to at most 24 kHz, Crappy to at most 8 kHz and 8 bits; both also quantize the signal.
Format definitionHistoryPureBasic moduleC sourceC headerJavaScript sourceC / JavaScript bundlePort contracts
Comparing WAV, RAU and MP3
“Theorie”, my own track · 76.86 s · 44.1 kHz · Stereo · 16 bits
| Profile | RAU | MP3 |
|---|---|---|
| Lossless44.1 kHz · 16 bits | 7.27 MB · 53.59% | 3.08 MB · 320 kbit/s |
| Mid24 kHz · 16 bits | 0.84 MB · 6.17% | 0.77 MB · 80 kbit/s |
| Crappy8 kHz · 8 bits | 0.19 MB · 1.41% | 0.23 MB · 24 kbit/s |
MB = 1,000,000 bytes; percentages refer to the WAV size. MP3 is always lossy. The Mid and Crappy references are close to the corresponding RAU file sizes; 320-kbit/s MP3 is considerably smaller than RAU Lossless.
Encode & decode
8/16-bit PCM WAV, mono/stereo, or RAU-26. Processing stays in your browser.
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