Ethernet/Network enabled DAC?

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The subject just came up in another thread and I would not dare to add 'off-topic' comments there. 🙂
I think the network audio thing is very exciting and have read development threads (e.g. peufeu on this forum) with great interest. But there is to my knowledge not a real, easy to make DIY product that came out of it yet.

The story: two months ago I was searching for a cheap silent office PC which should double as media/audio player when I stumbled upon a very cheap embedded CPU motherboard (Intel, details) and a free, open source, network audio server (pulseaudio, details) that is getting a lot of development attention a.t.m. I am not a gifted programmer, so the two things combined made sure I did not need to program much to get a alternative for a 'squeezebox' type digital out that doubles as very silent PC for ~$200 (for motherboard, memory, hdd, wireless card). :clown:

Network audio: The network audio server part is sort of dual purpose. First, the cheap PC is capable of playing digital audio from files on some noisy large volume hardisks (NAS) elsewhere in the house via a wireless network. Secondly, using pulseaudio, the 'sound-device' can be used by other computers on the network to play audio on. I use the first option mostly, as the PC doubles as a simple Intenet browser PC and therefore has a monitor connected anyway. But the second, real network server option allowed me to play music from a laptop through the DAC as well.

I am still fumbling around with the setup and have just added a cheap sound card (Chaintech AV-710) to get SPDIF out to the DAC (a Twistedpear OPUS) to see how that goes compared to USB.

🙂

To conclude: I am really curious to see if there are others that have chosen such an embedded PC + pulseaudio route and to read about their experiences. There might be things I have not thought of that make this a less optimal solution.

/ edit: completely forgot, I cannot comment myself the next 5 days.
 
I've done some fooling around with netjack to achieve similar goals. JACK itself is very powerful and makes it pretty easy to do fun stuff like inject filters or crossovers into the audio path, without requiring anything special from the player. Using BruteFIR with netjack for example should allow you to do the grunty crossover filter on a machine in the basement and transport the full multichannel stream over Ethernet to a silent machine with a multichannel sound interface to drive the amps. Then you can run mpd on the 'server' machine, with a nice mpd client running on the silent machine in the playback room.

It's fun stuff 🙂.
 
I am hitting the question of sending audio from windows to linux. Do you have experience with pulseaudio in this respect? From what I read pulseadio on windows is still very rudimentary. Is there a generic driver supported by major applications?

I played with jack on windows, it actually works and ASIO-aware applications can use it. The only missing piece is the windows port of netjack, unfortunately it is the crucial piece. If we had windows (and OSX) netjack, the network-enabled DAC with embedded linux would be simple.
 
Jack has indeed a good reputation and I spent some time a while ago to get it up and running, but I have not yet been able to use it in a sensible way.. It broke down every time I updated/upgraded and I experienced there are hacks and tricks needed to get it working with e.g. Amarok. Perhaps I should look into Jack again, especially combining it with brutefir is a very cool idea 🙂

Sorry, I have no experience with Pulseaudio on windows and do not know how operable it is by now, I wonder if ASIO awareness is really needed if the sound stream is buffered and forwarded to a sound server/deamon on another PC - latencies play a more important role on the remote PC, where the interface with the actual soundcard is.
If I understood correctly, pulseaudio could sort of replace 'netjack' or 'mpd', as it can take Jack output as input and sent this over network. From windows it should actually take any input (e.g. output from Foobar2k) and sent it over the network. I am curious too.

I have decided to wait for the official Ubuntu 8.04 release and add a RealTime kernel and hopefully an updated pulseaudio. If this is not satisfactory I'll try Jack again.

My personal worry is if pulseaudio actually does a good job with handling the soundcards. In my current setup it receives input from e.g the ALSA server via the Xine engine, and this goes to the soundcard. How can I check if using pulseaudio is any better or worse than direct input from ALSA or Jack, or others? I have not come further than a listening test, and I could not really tell.
 
So far I have had no major problems with jack but I am no jack power user at all.

FWIR pulseaudio has no quality driver for MS Win, making its use as a client rather complicated.

I mentioned ASIO because there is an ASIO jack driver which allows ASIO-aware MS Win applications to hook to the jack server. I assume there are not many MS Win applications with native jack support. But still the networking glue - netjack - is missing.

I would not worry about latencies when using asynchronous sound cards (i.e. PCI, USB asynchronous). It is all about bit perfection. It should not be difficult to find out how pulseaudio handles the audio stream and whether it can maintain bit perfection for various wave formats.

For standard USB (adaptive mode) some people say latencies make a difference, I have no personal experience.
 
I would like to show you my expirement in Ethernet audio.

I have use the Silex SX-2000U2 USB Device Server to connect the computer to the USB Sound Card (I use the USB Off-Ramp Turbo 2). The result is great - there is no problem to work with 24 bit 96 khz data sound.
Even it is work with Wi-Fi adapter connectid to the SX-2000U2.
The people have emotional shock when they hear the High End sound from notebook with wireless connection🙂 .
 
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