Ethernet Media Server

Many audiophiles would like to stream bit perfect FLAC or WAV files from a PC server or drive array to their hifi system. A number of great commercial solutions exist for 16 or 24 bits at either 44.1 or 48 khz, such as Apple’s Airport or Logitech’s Duet. Logitech’s Transporter seems like an excellent product to achieve 24 bit 96khz performance, but it costs over $2000 with shipping. These devices are difficult to hack. subscribes to the notion that “If you cannot open it, you don’t own it!”.

The ethernet audio server project is a low cost platform to stream high quality bit perfect audio from a hard drive to a high end DAC. Future improvements would include the ability to construct a digital crossover for custom speaker tuning. The entire system must have the ability to operate, set options, and tune parameters via a Web interface.

The platform:

The project is just getting underway and the essential components are under evaluation and testing. The platform is an Analog Devices Blackfin DSP that runs uClinux. Embedded Linux is extremely powerful and provides a robust set of capabilities right out of the box. The Blackfin BF537 DSP chip includes an on chip MAC for ethernet connectivity at 100mbits, PCM I2S ports, at low cost. Linux provides a very robust TCPIP stack, rich development tools, and proven open source code. A number a good efforts on the web using ARM micro-controllers have gotten off to a good start and then fell short due to either poor TCPIP performance or issues effectively transmitting PCM audio data to a DAC. A Linux 2.6 kernel running on a DSP chip solves both of these issues with native I2S audio ports, SPI ports for establishing DAC configuration, and a commercially proven or hardened ethernet connectivity.

An ideal basis for an audio server.

Below is a picture of a web page served by uClinux’s BOA web server running on the Blackfin DSP:

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Pulling FLAC files from a remote PC via a web page works, and the few test features enabled are controlled via different computers on the network. The Audio server can even be controlled via an iPhone.

There’s tons of work to make this viable. The next update will occur in February.