SD2 to TTA Converter

Sound Designer II (SD2) is a professional audio format created by Digidesign around 1988 as the successor to the original Sound Designer format. For over a decade, SD2 was the standard interchange format in professional recording studios, especially those on Macintosh systems. It stores uncompressed linear PCM audio at up to 24-bit resolution with sample rates used in professional production (44.1, 48, 88.2, and 96 kHz). A distinctive technical trait is its reliance on the classic Mac OS resource fork for critical metadata — sample rate, bit depth, and channel configuration — while audio data resides in the data fork. This design worked elegantly within the Mac ecosystem but created portability challenges when files moved to Windows or Unix. A key advantage was SD2's support for multiple channels in a single file and tight integration with the Pro Tools editing environment, enabling non-destructive region-based editing. The format also carried loop points and markers, making it valuable for sample libraries. As Avid Technology shifted Pro Tools toward WAV and AIFF, SD2 usage declined, but millions of legacy session archives still contain SD2 files needing occasional conversion.

TTA (True Audio) is a real-time lossless audio compression codec developed by Aleksander Djourik, with its origins tracing back to the early 2000s. The format reconstructs the original PCM stream bit-for-bit upon decoding, guaranteeing that no sonic detail is lost during storage or transfer. TTA handles standard CD-quality audio as well as high-resolution content up to 32-bit integer samples, making it suitable for everyday listening and professional archiving alike. Processing speed is one of TTA's defining strengths — the codec achieves fast encoding and decoding without heavy CPU demands, keeping it lightweight even on older hardware. The file structure supports ID3v1, ID3v2, and APEv2 metadata tags, so track information and album art travel with the audio. Hardware support appeared in several portable players, giving TTA a practical edge over some competing lossless formats. The open-source reference implementation ships under the GNU GPL, encouraging community adoption and third-party integrations. While newer codecs like FLAC have captured a larger share of the lossless audio landscape, TTA continues to serve users who value its simplicity and transparent compression.