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We have over twenty years of experience on embedded Linux, especially in signal processing and audio areas.

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HQPlayer 5 Embedded

Embedded version of HQPlayer is designed for building Linux-based music playback devices and digital audio processors. It can utilize both digital and analog inputs from various devices and output audio processed through the advanced DSP pipeline. Thus it can operate for example as a digital-in-digital-out upsampler processor and convolution / EQ engine, or used inside a DAC. It can also function as a UPnP AV Renderer and in addition there is also support for the HQPlayer Control API that can be used for implementing a custom GUI or other type of front-end utilizing the HQPlayer playback engine. HQPlayer Embedded has also a mobile device compatible web-based control and configuration user interface.

Optional support in custom builds for FFMPEG libraries for extending media decoding capabilities.

For digital room correction and other equalization purposes, selectable convolution algorithms are included. Convolution engine supports RIFF (WAV) format FIR impulse responses, which can be produced with suitable software, such as Acourate, Room EQ Wizard, Audiolense, or DRC.

HQPlayer OS

HQPlayer OS is a fully custom Linux-based operating system tailored and optimized for HQPlayer use. It includes both HQPlayer Embedded and Network Audio Adapter functionality in a single bootable image, making it easy to to deploy the media to these different use cases. The image can be simply written to a USB memory stick or other suitable storage media, such as (micro)SD-card and booted up, without requiring any other installation steps.

Network Audio Adapter

Network audio is especially useful to give freedom from cables when player is run on a wireless device, or there is need to wirelessly transfer audio data to the endpoint. Network audio also allows use of optical cabling for full galvanic isolation and long runs. Multi-access use cases.

With HQPlayer Embedded this allows having network link at both input and output sides of the player for maximum flexibility and isolation.

Processing is performed by the player application and the processed data is then asynchronously streamed over network to a very lightweight network audio adapter interfacing to the DAC. Asynchronous FIFO provides maximum isolation between processing and audio reproduction.

Supported source formats:

  • CDDA (Audio CD)
  • FLAC
  • DSDIFF (DFF, non-compressed)
  • DSF
  • RIFF (WAV, including DXD/RF64)
  • AIFF
  • WavPack (PCM and DSD)
  • MP3
  • RAW streams
  • Realtime audio inputs

Supported playlist formats:

  • M3U / M3U8
  • PLS


  • UPnP AV Renderer
  • Available as a full, custom made and optimized, bootable HQPlayer OS image
  • DAC specific output signal corrections
  • Software upsampling / downsampling with selectable algorithm up to 32-bit 3.072 MHz or down to 16-bit 32 kHz PCM (61 options)
  • Delta-Sigma modulators for upsampling PCM content up to 98.304 MHz 1-bit SDM (30 modulators, 3 SDM rate converters, 68 PCM oversampling options)
  • Direct DSD up / down rate conversions (3 options)
  • Selectable dithering / noise shaping algorithm (8 options)
  • 128 DSP pipelines for routing and mixing with various algorithms (max 48 DSD source channels)
  • Selectable convolution algorithm (FIR) for equalization, such as digital room correction (2 options), for PCM/DSD content
  • Optional high-frequency expansion for the convolution engine
  • Parametric equalizers for PCM/DSD content
  • RIAA equalization for vinyl sources
  • Software-based digital volume control for PCM and SDM (DSD)
  • Source content analysis to detect need for apodizing oversampling filter
  • Source content metering and analysis
  • Playback of DSF/DSDIFF files through any supported audio interface (PCM conversion and DSD rate conversion)
  • Selectable algorithm and noise filters for DSF/DSDIFF PCM playback (13 / 12 options)
  • Native/direct playback of DSF/DSDIFF files (native DSD, DoP v1.1 with both 0x05/0xFA and 0x06/0xF9 markers)
  • Playback of stereo, 2.1, 3.0, quadrophonic, 3.1, 5.0, 5.1 and 7.1 channel material
  • Speaker configuration for multichannel playback (delay and level) for PCM and SDM (DSD)
  • Matrix processing for routing, filtering and mixing channels with gain, for PCM/DSD content
  • Network endpoint support with Signalyst Asynchronous Network Audio Adapters
  • Support for ID3v2 tags on AIFF, DSF and WAV files (versions 2.2, 2.3 and 2.4)
  • Smooth level limiter for clipped material
  • "Dual wire" channel bonding support to reach 2x rates, PCM and DoP (DSD)
  • 64/80/128-bit and arbitrary precision floating point processing
  • Support for 128 channels (max 48 DSD source channels
  • Full support for multi-core processors
  • DSP offload to GPU using NVIDIA CUDA (only on Ubuntu, Fedora and Debian -based systems)
  • Headphone cross-feed processing
  • Support for ReplayGain 2.0 metadata

Resampling filters:

  • 40 linear phase
  • 3 intermediate phase
  • 11 minimum phase
  • 4 impulse optimal
  • 3 closed form

Dithers and noise-shapers:

  • 4 dithers
  • 5 noise shapers

Delta-Sigma conversion:

  • 30 modulators
  • 68 oversampling filters (64x - 2048x)
  • 3 SDM-to-SDM rate converters
  • Direct rate conversions
  • Digital volume control
  • Convolution engine
  • Parametric equalizer
  • Routing and mixing

Control applications:

Media server software:

Hardware with HQPlayer Embedded pre-installed:

Input hardware:

Recommended hardware:

Note! HQPlayer Embedded operates without license key in trial mode for 30 minutes at a time and then needs to be restarted to continue!

HQPlayer Control

Source code for the HQPlayer Control command line utility is available here (re engine v5.15.0).