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Zapex ZP-100: AC-3 5-Channel Surround Encoder

Despite a growing surround mastering and production market for HDTV, audio and DVD releases, the number of available encoding products is relatively small.

Despite a growing surround mastering and production market for HDTV, audio and DVD releases, the number of available encoding products is relatively small. The ZP-100 from Zapex Technologies is a single PCI card solution that provides high-quality Dolby Digital (AC-3), MPEG audio and linear PCM stream encoding with a host of useful playback and encoding features for optimizing audio quality.

A real-time encoder certified by Dolby Labs, the ZP-100 system is available in either 5.1 or 2-channel (5.1-upgradable) versions. The unit consists of a PCI card for real-time digitization, control software and a breakout cable with four XLR AES/EBU digital inputs (channels 1-8). A stereo S/PDIF input, SMPTE LTC input and S/PDIF (IEC 958) BNC and XLR plugs connect the encoder’s output to a Dolby Digital and/or MPEG audio player. An RS-422/232C adapter links the computer’s serial port to an external transport for Sony 9-pin control.

As all DSP takes place on the card, hardware needs are minimal: a Pentium II 233 or higher processor running Windows NT Version 4.0 with Service Pack 3 or higher. other requirements include a PCM audio player for source PCM audio stream playback and a Dolby Digital and/or MPEG audio decoder for monitoring

The encoder’s integrated capture feature eliminates the cost of a separate capture card. Capture file options include elementary stream, with and without timecode (AC-3 disc file format), and IEC 958 stream with/without timecode (.WAV file format). IEC 958 stream options include professional 32-bit, Ch-1 16-bit, Ch-2 16-bit data packing and consumer mode. The ZP-100 can simultaneously encode and capture either Dolby Digital and PCM, or MPEG Audio Layer 2 and PCM, and the encoded bitstream can be played immediately after capture. The unit offers a Region Save Editing feature, which allows segments of a Dolby Digital, MPEG Audio or PCM stream to be edited and saved as a separate file. A timecode-based batch encode feature automatically applies a set of user-defined parameters to multiple files, and the unit can be configured for manual,semi-automatic or automatic encoding.

The software is divided into three applications: A GUI provides basic setup for controlling and navigating the system, the encoding software provides the means to adjust and store encoding parameters and a Playback Tool utility includes sound peak wave display, region save and bitstream analysis.

During encoding, the ZP-100 can operate in two modes. The File Capture mode is for capturing a file to disk for later playback, such as in DVD production. The Dynamic Encoding mode is used for creating parameter files or doing Broadcast Encoding where a PCM source is encoded and played, but not saved as a file. The system’s most powerful attribute is the ability to change parameter values while the ZP-100 is encoding, providing the user with instantaneous audible feedback while tweaking settings.

Adjustable AC-3 parameters include bitstream service type (standard “Complete Main,” Emergency, Visually/Hearing Impaired, Voice over/Karaoke, etc.); sampling frequency; bit rate (56,000 to 640,000 bps); LFE channel in/out; nominal down-mix levels of the surround and center channels; embedding a Dolby Surround signal into the Dolby Digital stream; copyright bit setting; dialog normalization; dynamic range compression (five presets); RF overmodulation protection; main channel lowpass filter (mainly used to improve signal quality at low bit rates); LFE lowpass filter (120Hz roll-off); DC filtering; 90Degrees surround channel phase shift; -3dB surround attenuation (for theater applications); de-emphasis and more. Features listed above are for current ZP-100 systems offered, Version 4.0. The Zapex ZP-100 5-channel system (card, software and interface cabling) is priced at $5,500.

Zapex Technologies Inc. (, distributed by Microboards Technology; 1721 Lake Drive, West Chanhassen, MN 55317; 800/646-8881; 612/556-1600; fax 612/556-1620;