This paper investigates VLSI architectures for digital processing (DSP) functions amenable to low energy operation with scalable performance for H.265 high efficiency video coding (HEVC) applications. First, we describe and experimentally evaluate a novel adaptive computing fabric. Second, we propose an energy-efficient method to scale the performance of the fabric for large images or for meeting stringent real-time computation requirements. A series of tradeoffs for exploiting efficiently the application space for general purpose DSP acceleration are proposed. We experimentally show how the proposed computing fabric is reusable for Filters, FFT and DCT acceleration with a scalable throughput. We report on the design and implementation of the fabric on a Xilinx FPGA device and show how regulated-parallelism augmented with in-memory processing techniques impact performance and power efficiency. The FPGA prototype demonstrates a sustained throughput exceeding 10Gbps irrespective of the kernel and image size for H.265 HEVC applications.