FLAC to SD2 Converter

Create Sound Designer 2 files from lossless FLAC

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Perfect Quality

FLAC to SD2 is lossless — every sample from your FLAC source transfers perfectly.

Legacy Pro Tools

SD2 is the classic Digidesign format — produce from lossless FLAC for vintage sessions.

Online Processing

No Pro Tools needed — convert FLAC to SD2 in your browser.

How to convert FLAC to SD2

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose sd2 or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your sd2 file right afterwards

About formats

FLAC (Free Lossless Audio Codec) delivers mathematically perfect audio reproduction at roughly half the size of an uncompressed WAV file. Maintained by the Xiph.Org Foundation and released in 2001, it quickly became the de facto open standard for lossless music archival. The encoder applies linear prediction to model each audio block, then codes the residual through Rice partitioning — exploiting the statistical distribution of prediction errors for strong compression without discarding data. Bit depths up to 32 and sample rates up to 655 kHz are supported, exceeding the requirements of high-resolution recordings. Hardware support is extensive: smartphones, car stereos, Blu-ray players, and virtually every desktop media application decode FLAC natively. Streaming services such as Tidal and Amazon Music use FLAC for lossless tiers, underscoring industry trust in the codec. Three standout benefits make FLAC compelling. First, complete bit-for-bit restoration of the original signal upon decoding. Second, embedded metadata via Vorbis comments and album art keeps libraries organized without sidecar files. Third, open-source licensing means no patents or royalties, removing legal friction for developers and hardware vendors.
Initial release: July 20, 2001
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.
Initial release: 1988

Frequently Asked Questions

Why convert FLAC to SD2?

SD2 is the Digidesign format for legacy Pro Tools. Lossless FLAC ensures perfect quality for vintage session compatibility.

What opens SD2?

Pro Tools, Sound Designer II, Audacity, and classic Mac audio apps support SD2 files.

Is FLAC to SD2 lossless?

Yes — both store uncompressed audio. FLAC decoded to SD2 preserves every sample perfectly.

Is SD2 still needed?

SD2 is for legacy Pro Tools sessions and archived projects — modern sessions use WAV or AIFF.

Can I batch convert?

Upload multiple FLAC files and produce SD2 output simultaneously.

FLAC to SD2 Quality Rating

4.7 (3 votes)
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