DDi Codec — for Dolby B/C NR 4+

DDi Codec is a precise digital emulation of the classic Dolby-B/C noise reduction system for analog audio tape. It is the world's first dedicated software for decoding or encoding Dolby-C formatted audio in digital domain, along with full backward compatibility with Dolby-B. Powered by the proprietary DSP engine, the decoding/encoding can be performed in realtime, which allows for instant processing, monitoring and fine-tuning.

Deeper optimal result can be achieved by using the fine-tuning tools that come with the software, as specified below:
• Reference Vernier: The primary tool for calibrating Dolby Reference Level in a progressive and interactive manner. It supports either objective calibration (with Dolby Tone) or subjective estimation (trial-and-error without Dolby Tone).
• Play Trim: Originally developed by NAD and Dolby, this tool compensates for signal degradation with aged pre-recorded tapes.
• Azimuth Correction: a limited-effect tool for remedying slight phase displacement and high-frequency loss caused by the azimuth error of the playback head.
• Gap-Loss Compensation: a limited-effect tool for counteracting slight playback head wear.
• EQ Converter: a utility for converting between IEC 120μs and 70μs EQ schemes, offering flexibility when the tape player/recorder lacks this option.
• Ref. Tone Generator: offers 400Hz 0dB signal at Dolby Reference Level for easy calibration.
Each of these tools can operate independently of the Dolby-B/C codec, which can be used for refining the audio digitized from analog audio tapes, regardless of whether Dolby NR is involved.

DDi Codec is a stand-alone GUI app without relying on any DAW host. It allows the computer to perform as a outboard Dolby-B/C NR unit in one of the following four scenarios:
• Audio-In to File (a digitizer/recorder).
• File to Audio-Out (a player).
• File to File (an off-line processor, with batch capability).
• Audio-In to Audio-Out (a through processor, with slight delay).

Currently supported audio formats are:
WAV, FLAC, AIFF: up to 96k/24bit.
MP3, AAC, M4A: up to 48k/VBRS.
* Excluding some proprietary variants having the common file extensions, or additional format-normalization may be required.

A VST plugin is also available after the app has been installed.


* Dolby-B and C are the tape noise reduction systems developed by Dolby Laboratories.