[linux-dvb] receiving on a server and broadcasting to machines?
linux.luser at myrealbox.com
Fri Jan 5 19:24:51 CET 2007
On 5 Jan 2007, at 16:23, peter pilsl wrote:
> Not sure, if this is the right mailinglist ... I would be happy if
> anyone could point me to ...
> I want to to be able to watch TV on two of my laptops (maybe
> different people looking different channels at the same time) So
> instead of buying two expensive USB-DVB-cards, I was thinking about
> buying one cheaper PCI-card and put it into the local server and
> then broadcast all the channels over the intranet. I've seen such a
> broadcast-option in my player Kaffeine.
> If it means that a client can connect to the server and request a
> certain channel and then this channel is transmitted over the
> network then I would probably be ok !?
You're pretty much describing a Linux-based "networked PVR" (personal
video recorder) here. There are a couple of other projects besides
MythTV, but I'll leave recommendations of others to others.
> So now I dont have much idea what this would mean for the cpu-load
> and the network-load.
> The clients are connected via WLAN to the server and 20 MBit is a
> realistic transfer-rate that is achieved all over the covered area.
> I dont have any clue how much bandwith a dvb-stream needs and if
> the server "broadcasts" the original dvb-stream or an encoded
> version or whatever.
Standard-definition (SD) TV, conventional digital TV and DVD-quality
footage is fine, even on "re-purposed" machines and (I think) wifi.
This is typically 720 x 480 pixels, I think. You would certainly not
get more than 2 streams across wifi, tho'.
> If broadcast means that the server reads all channels simultanously
> and send them over the network then the server and network would
> break down within seconds I guess ... If it means that a client can
> connect to the server and request a certain channel and then this
> channel is transmitted over the network then I would probably be ok !?
Commonly the server ("backend") records one channel or one channel-
per tuner card. It can stream one or more channels across the network
and the clients ("frontends") tell the server when to change channels
or stream a different recording.
> I dont even know if the client then has all abilities that dvb
> brings : like stopping the TV and continue lateron - using
> programpreview and so on.
Projects such as Myth have done all the work already, and provide a
telly-like interface (or rather set-top-box-like interface) for these
> The server is a old 500MHz-Celeron with 512MB which is more than
> enough for a SOHO-fileserver but maybe not for dvb-server!? On the
> other hand : I dont want to watch TV on that server. It should just
> distribute the signal.
I _think_ that'd be ok, at least if you were capturing digital
signals (using a DVD-T or DVB-S tuner card), although you wants loads
of disk space for scheduled recordings. I would probably prefer to be
using a 1ghz machine, myself. Transcoding - converting to a different
compression-rate or -type - would be very slow on such a machine, but
that may not matter if you can stream live; MythTV can automatically
transcode recordings - so that they take up less space - in the
background during idle time. The frontend machines should be > 1ghz
for SD playback.
See you on the Myth mailing-list!
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