libttaR

Tau’s True Audio (TTA) codec rewrite

What is TTA?

TTA is a lossless audio codec designed around realtime hardware coding. The codec has no tunable parameters, and each input produces a unique output. It supports 8, 16, and 24-bit PCM.

http://tausoft.org/wiki/True_Audio_Codec_Overview

Building

edit then run ./make.sh

I recommend compiling with clang.

Platforms

The library is platform agnostic. The program is POSIX native and has a mostly native (mostly working) Win32 port via MinGW.

Processors

2’s complement integers are assumed.

While developing, I mostly tested on:
- AMD Ryzen 7 1700 (primary tuning)
- Intel Celeron N2830 (secondary tuning)

honorable mentions:
- IBM PowerPC 7400 (intrinsics)
- ARM Cortex-A53 (intrinsics)

Defines

NDEBUG
disables all debug assertions

LIBTTAr_OPT_DISABLE_UNROLLED_1CH
disables the unrolled mono loop

LIBTTAr_OPT_DISABLE_UNROLLED_2CH
disables the unrolled stereo loop

LIBTTAr_OPT_DISABLE_MCH
disables the general/multichannel loop

LIBTTAr_OPT_DISABLE_SIMD_INTRINSICS
disables SIMD intrinsics

LIBTTAr_OPT_SLOW_CPU
for weak and/or old CPUs (specifically the Intel Celeron N2830)
fine-grained suboptions in ‘src/lib/common.h’

Basic Usage

$ ttaR encode file.(wav|w64)
$ ttaR decode file.tta

By default, ttaR will multithread with the number of coder threads equal to the number of online processors.

Read the man page (./man/ttaR.1) for a full list of the options.

About

This project started as a fork of ttaenc 3.4.1-linux (2007). Any code from ttaenc was put into the library, and the CLI program was completely rewritten.

The library prioritizes speed. So, its memory usage is a bit bloated to avoid some bounds checks. (The safer alternative is 15-20% slower.)

The library is just a collection of functions for reading from one buffer and writing to another with some support functions to calculate values. It does not allocate, print, nor make any other syscall. (Though it can abort, but should not, if NDEBUG is not defined.) It does not even need libc as long as your compiler has a builtin memset and memmove (both, ie, not gcc). So fairly bare-bones as far as codec libraries go.

The two codec functions are reentrant, so you can code as few samples at a time with buffers as small as you want. ttaR (CLI util) 1.0 did this, but I replaced it with doing the whole frame at once in 1.1 because it’s a little faster and it simplified the source a bit.