ZTX comes as three APIs to allow for maximum flexibility, scaleability and performance: ZTX Core for maximum quality, file-based workflows; ZTX FX, optimized for lightning fast real-time performance as well as consistent and low CPU use; and ZTX Retune, a specialized toolkit for pitch correction and for creating voice special effects similar to "that sound" known from many current music releases. Availability of the three APIs varies with version and licensing model, so ZTX is scalable both in terms of technological as well as budgetary considerations.

The ZTX Core API focuses on delivering maximum quality with full parameter control. It provides high quality transient-preserving time stretching and formant corrected pitch shifting, pitch correction, a transcribe mode for extreme stretch factors, full phase-locked multichannel support, and its audio properties can be configured in a wide range to suit different types of material, such as monophonic or polyphonic music, voice/dialog, and even complex material such as multi-channel film sound. ZTX Core is optimized for quality rather than low CPU load, so it excels when used for file-based processing in mastering, post-production and other high-end applications. It can be used in real-time provided sufficient CPU resources, and a dedicated real-time Preview mode is included.

The ZTX FX API has been developed with two things in mind: speed and efficiency. While the ZTX Core preview mode does fast realtime time stretching and pitch shifting, the ZTX FX API is so fast it leaves everything else behind. It offers real-time transient-aware time stretching and pitch shifting for polyphonic music at unprecedented efficiency. ZTX FX is the world’s first time stretching algorithm that performs DSP magic without using any trigonometric functions – resulting in dramatically increased performance over traditional FFT based methods. This translates into increased battery life on handheld devices, more tracks that can use time stretching and pitch shifting in real time, and more voices on a sample player. ZTX FX can also be configured to utilize a near-constant amount of CPU for all settings. It's a very simple API with no callbacks and no extra code required for configuration – create your ZTX FX instance and process data with only 2 calls!

ZTX Retune is our API for pitch correction. While ZTX Core can correct pitch, ZTX Retune is optimized for this purpose, and allows stricter processing to create the popular "pitch locked" vocal sound found in many current music productions. It is entirely sample rate independent, can easily be configured on a per-key basis, and also allows native processing of PCM data in “short” format – which results in better performance on mobile devices. 

ZTX Core's Transcribe Mode uses a content aware algorithm to time stretch and pitch shift audio by up to 4x the original length without losing information critical to transcription, such as attack transients. While ZTX generally allows changing pitch or speed in a wide range at very high quality, Transcribe Mode enables good quality at extreme values as well.