SONICblue's Rio Central is a high-fidelity home stereo component that stores up to 650 CDs (or 6,500 individual songs) on its built-in 40GB hard drive. SONICblue describes the Rio Central as being “As simple to use as a CD player, but as smart as a PC” — a Linux-based PC, that is!

The system is intended to function as a standalone audio system, making it quick and easy to store your music (“you load your CDs, the device does the rest”) and create an essentially unlimited number of customized playlists. Thereafter, a large display, intuitive interface, and advanced search features are meant to make it easy to find the music you want instantly. Plus, the system optionally offers suggestions based on tracking your listening habits.

The Rio Central rips CDs to the hard disk using its integrated CD-RW drive, and looks up album and artist info in an embedded Gracenote CDDB database (if there is a miss on the local database, the device can look up more current info in an online CDDB database). The Rio Central supports common audio formats including MP3 and WMA, and can be upgraded to emerging digital-audio standards as they become available. The device can write custom CDs in multiple formats including standard audio, MP3-CD, or data.

The device can also be used as the basis of a broader 'Rio experience', serving one or more companion Rio Receiver 'thin clients' (which also run Embedded Linux) via HomePNA (phone line networking) or Ethernet, and can download files to Rio portable MP3 players via USB. The device is broadband-ready (via an external USB-to-Ethernet adapter), includes a built-in 56Kbits/sec modem (for users without broadband access), and provides a 10Mbits/sec HomePNA connection. The system comes with PC software that allows users to manage their music library from a Windows PC over either Ethernet, HomePNA, or USB.

Its audio specs include . . .

• Max. output level: +1.51V
  
• Frequency response: +0,-0.227dB (20Hz – 20kHz)
  
• Signal-to-noise ratio: Better than 101.5dB (A-weighted)
  
• THD + N (997Hz, 0dB FS): Better than 0.002%
  
• Channel separation: Better than 115dB (at 1kHz)

Here are high-resolution photos of the front and back of the device.

What's in the box?

The Rio Central's embedded computer is based on a 206MHz Intel StrongARM SA1110 system-on-chip processor along with 16MB of system RAM. A built-in multi-gigabyte hard drive contains the Linux kernel and player control software. A 1MB Flash memory chip has sufficient software in it to boot the unit from either a CD or the hard drive.

The device's input/output interfaces include . . .

• Combined HomePNA (phone line networking) and 56kbps modem
  
• USB host port (using a slightly modified Linux OHCI driver) for keyboards, Ethernet adapters, and gamepads
  
• USB slave port (using a custom driver)
  
• Consumer IR and front panel buttons (using a custom driver)
  
• Analog line level audio outputs and optical digital audio output

Rear panel I/O connectors

According to Jeff Hastings, VP of engineering for SONICblue, the Rio Central's embedded software is derived from that of the Rio (formerly empeg) car player, which was developed from an early version of the Debian/ARM port with the addition of Russell King and Nico Pitre's kernel patches. The system's Embedded Linux operating system is based on a 2.4.13-ac8-rmk1 derived ARM kernel along with various other Debian/ARM binaries, plus some custom software.The GUI control software talks straight to the framebuffer device using the standard /dev/fb interface. Various SDL games (with USB joypad support) are included, as well as access to a shell prompt from a USB keyboard.

The Rio Central's Linux-based development project was not without its challenges. “The Linux VM turned out to be an ongoing source of difficulties,” recalls Hastings. “unfortunately, Rick Van Reil's VM is not very well suited to embedded devices which need to 'lock down' memory — although the 2.4.13-ac8 kernel was better. Another problem, resulting from a bug in the Linux ARM floating point emulator, also had to be tracked down and fixed.”

Why use Embedded Linux?

“Embedded Linux was originally selected as part of the development of the empeg (later Rio) car player,” says Hastings. “It was chosen primarily for cost, ease of development using open source tools, and personal preferences towards Linux. The original empeg car player developer, Hugo Fiennes, had already ported it to an ARM platform. We are very glad that we used it.”

“All our modifications to GPL source code are made available to customers who buy the unit, under the terms of the GPL,” explains Hastings. “Where we've written our own drivers to go into the kernel, we've also placed these under the GPL. Other parts of our source code that interact with the Rio car player have been made available under the GPL. We've pushed our patches back upstream, although most of our modifications to the 2.4 kernel have been in quite specific drivers.”

“Linux will continue to play a critical role in the development of our embedded products,” adds Hastings.

When can I get one, and how much will it cost?

The Rio Central is available online from SONICblue's website for $1499.95. A note on the Rio Central ordering page currently says: “Next shipment due-in soon!”

---

 
This article was originally published on LinuxDevices.com and has been donated to the open source community by QuinStreet Inc. Please visit LinuxToday.com for up-to-date news and articles about Linux and open source.