dtj v07-04 1995

This document, Volume 7, Number 4 of the Digital Technical Journal from 1995, focuses on two primary themes: Audio and Video Technologies and UNIX Available Servers, Real-time Debugging Tools.

I. Audio and Video Technologies: This section highlights Digital's advancements in integrating multimedia into 64-bit RISC Alpha systems.

• DECtalk Software: Details the porting of the DECtalk text-to-speech system from a hardware-based product to a multithreaded software solution for UNIX and Windows NT, emphasizing natural-sounding, highly intelligible synthetic speech and its efficient implementation on Alpha processors.
• The J300 Family of Video and Audio Adapters: Two articles describe the architecture and design (both hardware and software) of Digital's J300 adapters (e.g., Sound & Motion J300, FullVideo Supreme). The goal was to treat video data like any other data type, ensure independence from the graphics subsystem, and keep costs low. The software architecture emphasizes asynchronous I/O and innovative use of queues for real-time performance on non-real-time operating systems.
• Software-only Compression, Rendering, and Playback of Digital Video: This paper explores the feasibility and performance of processing digital video (compression, decompression, rendering, and playback) entirely in software on general-purpose Alpha processors, without specialized hardware. It discusses various industry-standard compression schemes (JPEG, MPEG-1, H.261, INDEO) and rendering algorithms (scaling, color conversion, dithering).
• Integrating Video Rendering into Graphics Accelerator Chips: This article details the design of Digital's graphics accelerator chips (Dagger, TGA2) that integrate video rendering primitives like filtering, scaling, and color conversion directly into hardware. This approach significantly improves frame rates and image quality for video display, especially for enlarged images, by offloading intensive pixel processing from the CPU.

II. UNIX Available Servers, Real-time Debugging Tools: This section covers enhancements to the UNIX environment for mission-critical applications.

• Technical Description of the DECsafe Available Server Environment (ASE): This paper describes Digital's high-availability solution for UNIX systems. DECsafe ASE is designed to detect and reconfigure around host, storage device, and network failures, supporting standard SCSI hardware in shared storage configurations and employing mechanisms to prevent data corruption due to network partitions.
• Parasight: Debugging and Analyzing Real-time Applications under Digital UNIX: This article introduces Parasight, a suite of real-time debugging and analysis tools developed by Encore Computer Corporation. It addresses the limitations of conventional UNIX debugging tools by allowing users to debug and analyze running, multi-program real-time applications non-intrusively, monitor variables continuously, and perform on-the-fly execution analysis.