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Ask Slashdot: Audio/Video Networking Solutions for Linux? 57

Posted by Cliff
from the isn't-this-cool? dept.
Brad Andrews asks: "I recently finished building a new house, and networked it to provide central control over ambient audio levels and possible distributed video. I'm curious whether anyone has heard of a linux-based solution for central video and audio service, with a focus on MP3 and DVD, that I could combine with TV out ports and AC-3 decoders so I can watch the same movie from anywhere in the home. I'd prefer an x86 architecture, but if there is a complete integrated solution on another platform (StrongARM?) I would be interested in that as well. "
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Ask Slashdot: Audio/Video Networking Solutions for Linux?

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  • by Anonymous Coward
    I would love to see a networked audio device, something like an AD/DA convertor that you can feed via ethernet. Preferable via IP. If it could play & (realtime) record MP3 audio it would be even better.

    The missing link between my stereo system & my network.

    Better still, have all audio components receive & transmit their signals over IP.

    With modern 100 Mb ethernet you could do a lot that way...

    Haven't seen anything like that yet. A basic non-MP3 player should be cheap enough to make. Any hardware hackers around? I could even see some interesting business applications.

  • Linux can play Quicktime fine. It's just virtually every other format that it has trouble with (MPEG, AVI, etc., since most of the movies out there use proprietary codecs such as Indeo)
  • Considering the amount of money you are going to spend on all your audio/video stuff, I think hiring a Linux hacker to write all the needed software wouldn't hurt your pocket much ;-)
  • If you really want to distribute digital audio and video streams throughout the house, IEEE-1394 (and HAVi) was designed for it. Support is still pretty sparse even in the consumer-electronics arena, but it's coming. Linux support is farther off still. But at 400-1600 Mbps, it's in the same bandwidth ballpark as Ultra2/Ultra3 SCSI.
  • Just thought that I'd point out that mpg123 already can take audio from stdin... Just specify 'mpg123 -' on the command line and it looks at stdin. This works quite well for Shoutcast audio by the way. This is something worth looking at for home audio since there are so many channels. Just hope you have a fast Internet connect!
  • People won't be able to unpack a home media network for Linux from a nice .tar file until somebody builds a prototype. It seems like you've got the money, so it's just a question of your time and how much Linux talent you can scavenge.

    Mp3: linux support is great and the performance requirements are low enough that you won't need incredible hardware. At home we plug my laptop into our desktop machine, and we stream mp3's over the network with NFS and play them all the time. Even a Pentium/133 class machine, hooked up to a pair of good pair of speakers, could be a good sound system for a room. You could dispense with screen and keyboard and operate the machine entirely from the ethernet. Networking:Don't buy into one of these crazy phone-line or power-line networks. Since you're building the house, have it wired with gigabit-ethernet ready cable with a topology that would enable switched ethernet. You could probably start with 100 Mbit/S unswitched and upgrade in the future if necessary. DVD This is an area where Linux is behind. With MpegTV you can play MPEG streams -- it's a shareware product, but they do maintain it, and you've got a budget, so that's fine. Linux can also talk to DVD drives on the hardware level, but Linux cannot yet read the UDF filesystem which is used on DVDs. Top men are working on it, but there is always some risk when you base future plans on a product which isn't shipping: be it free or commercial. That said, if you've got a budget, a donation of $500 could make a big difference to a free software author and convince him to code in a feature or fig a bug for you.

    Chips: The mainstream of Linux is on the x86 and you'll have an easier time with x86 machines since the most software is available for them. The worst things, on the two ends of the market, about the x86 are: (1) it's 32-bit (not 64) and (2) it's a power pig, requiring lots of cooling fans and huge cases. If you can cope with these issues, this is the conservative solution.

    If, on the other hand, you want to take a RISC, look at the Alpha architecture on the server end and something based on ARM or MIPS on the client end. These days you could almost certainly find a tiny RISC machine without a cooling fan that could, at the very least, stream MP3's off the net into your stereo.

    Overall:Start by wiring the house for ethernet. Set up a server and at least one client and try to set up MP3 service. At this point you can experiment with different architectures. Watch emerging technology for Linux, and there is a good chance that you'll be able to upgrade to the DVD server you want.

  • I've got an interesting script running on a machine here that allows for control of x11amp via a webpage check it out url is

    http://reboot.sixsteps.org:3333/

    I'm thinking something like that where you could just go to any computer in the house and dial up some music for the abient speakers would be versy cool. Email me if you want the script.
    - MbM
  • I was just compiling my kernel today and I noticed something that I believe would be of interest to you. It's called IP Multicasting and I found the info under Network Options in the make config script. After reading the web page about it, it looks very interesting and worthwhile. Check the page out at http://www.teksouth.com/linux/multicast/. Enjoy! [teksouth.com]
  • is that most decoder cards don't have drivers
    Right, some hardware vendors are being a cry babies (wah!!! you have to sign a NDA wah!!!)

    UDF isn't yet supported.
    Well, it's getting there [trylinux.com] and is not that important right now

    what's exciting is that some DVDs seem to be able to be played [rpi.edu]
    --
    Four years in jail
    No Trial, No Bail
  • checkout http://www.smarthome.com for some options.

    I would stay away from running all the A/V over the LAN. (of course you want all your LINUX boxes networked together though)

    Maybe one central box that controls all A/V, Power HVAC etc.

    My main system has an X10 interface to control power devices throughout the home. I can dialin, enter a passcode (DTMF), and have my system turn my routers on or off, dialback to ISP etc. The X10 device can also receive and act on wireless motion detectors...

    With IR recording and transmitting I can control most consumer devices in the home from my computer. This requires IR distribution throughout the house.

    The easiest way to do Video distribution is to modulate your line level video to a unused channel on your cable TV wiring. Then you can simply tune any tv in your house to channel 61 and see your computer screen. :-)

    Check out smarthome's website. The may have a computer controlled A/V distribution system, if not I remember one in an old "circuit cellar" article (back in the byte days)

    The following software is available: (all free (beer) and open source)

    1. vgetty - controls voicemodem to allow a single phone line to take care of ISP connectivity, voicemail, fax with hook for scripting using touch tone decoding

    2. heyu - software to drive serial X10 interface for power control. CLI

    3. LIRC - linux project for IR remote control, recording and playback of IR commands from existing remotes
  • The problem with trying to base your home entertainment system on PC hardware and software is a matter of proprietary algorithms. AC-3, DTS, Dolby Pro Logic, THX etc, etc... Motorolla manufactures a DSP for $20 (in bulk) that will detect and DECODE all of these signals and send them to your respective Digital-Analog Converters. In other words, it should be dirt cheap to replace your reviever, DVD, CD, tuner with a PC with the latest from sound blaster. Unfortunately the licensing for these technologies would make a board cost $2000, just like a receiver that will do this stuff. We need to build software and libraries for Linux, etc... that emulates these decoding algorithms in the same manner that SSLeay was built. It's the only way you will be able to make your PC the center of your entertainment center. Please correct anything that is incorrect in here, all my research in the subject is based off of web sites....
  • If your home network is switched Ethernet, it'll support IP multicast. So, you can take advantage of this by multicasting your video and/or audio, and tuning into it whereever in your house (& however many times) you wish.

    For example, you can use a program like " liveCaster [live.com] " to multicast your MP3 streams. (There's a Linux version.)

  • This is the preferred way to do it. I've worked on some projects building Outdoor Broadcasting vehicles which are technologically the most crammed spaces you could imagine. Think 10 kilometres of cable in 12 meters of truck....
    The audio and video monitoring is almost always set up as a central matrix router feeding analog or digital video and analog audio to the different work positions inside the truck. Control of what goes where is done by custom button panels at each position. The distribution is done at line levels for audio and then levels and mono/stereo are selected at each position. Amplifiers are local, most of the time built into the speakers. If I were to build somethin like this in a house I would definitely have a central matrix controlled by some computer resource, with some audio-follows-video implemented, and audio fed via either AES/EBU digital or balanced 0 dBu analog.
    Video would ideally be S-video or component.
    Running destructively compressed audio like MP3 where bandwidth is not an issue (ie in a LAN or in an analog situation.) is imho stupid beyond comprehension, mainly because destructive compression sucks snooker balls through 14.4 dialup connections. There are places where you can benefit from it, yes. But not at home.
  • check out the cajun project;

    http://cajun.current.nu/

    which has a template for what you are trying
    to do.
  • Ok, it took me a while to get back, but here's the basic idea:

    I already cabled the house before the walls were finished. I'm definately putting a full system in each major room (bedrooms, kitchen, living room, etc.) so I'm not looking for a dumb terminal or thin client type solution.

    The idea was that, since MP3 and DVD are totally digital, there's no sense trying to pipe analog output around the house on a seperate set of wires, or wasting more space on stereo components in every room, if I could use the network as a sort of distributed entertainment center. I was particularly interested in focusing on the server for input and storage, and the living room box for high-end output. Every other machine would need average capabilities, but only stereo sound output. I have heard that the Diamond MX3000 sound card has hardware AC3 decoding capabilities, and even if it isn't yet supported under Linux I'm looking at the long term.
  • Axis provides DVD servers... you could put 5 or 6 DVD drives in a server...

    Axis products have been relatively reliable for all of our uses...

    http://www.axis.com/products/cd-rom_se rvers/ [axis.com]

    is the address

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