SD2 to CVU Converter

Browser-based SD2 to CVU audio converter

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Secure Conversion

Your SD2 uploads are deleted immediately after conversion. CVU output files are removed from our servers within 24 hours.

Rapid Conversion

Our servers convert SD2 to CVU quickly, even for longer recordings. Download your result as soon as processing finishes.

Effortless Workflow

Upload your SD2, pick CVU as the target, and download the result. Three steps, no learning curve, no registration wall.

How to convert SD2 to CVU

1

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

2

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

3

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

About formats

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
CVU is an unsigned variant of the CVS telephony audio format, differing in how delta-encoded values are represented in the binary stream. While CVS stores slope delta values as signed quantities, CVU treats them as unsigned, shifting the numerical interpretation of each sample. Both share the underlying CVSD modulation technique — 1-bit adaptive delta coding where step size varies according to recent output bit patterns — operating at comparable rates, typically 16 kbps for narrowband voice at 8 kHz. The signed-versus-unsigned distinction matters at the decoder, where correct interpretation determines proper waveform reconstruction. CVU files appear in telephony and embedded communication contexts where hardware adopted the unsigned convention. A practical advantage is straightforward interfacing with systems using unsigned arithmetic natively, avoiding sign extension in decoders. Like its signed counterpart, CVU achieves extreme bandwidth efficiency, compressing voice into compact bitstreams for constrained links. SoX supports CVU, providing a reliable path for converting these niche telephony recordings into modern formats for analysis or archival.
Developer: CCITT / ITU-T
Initial release: 1970

Frequently Asked Questions

Why convert SD2 to CVU?

Since Sound Designer II support is declining, converting to CVU safeguards your professional recordings for future use.

What programs can open CVU?

You can play CVU using SoX, specialized voice processing tools. It works out of the box on most systems with standard audio software.

Does converting SD2 to CVU affect quality?

Lossless-to-lossless conversions preserve all audio data. When the target uses lossy compression, some quality reduction is inherent in the codec.

How many SD2 files can I convert in one go?

Upload as many SD2 files as you need and convert them to CVU simultaneously. The batch feature handles multiple files efficiently.

What happens to my files after conversion?

Your original SD2 is deleted as soon as conversion ends. The resulting CVU is available for download and automatically removed within 24 hours.