[linux-dvb] Re: Why compress a VDR movie again ?

[Emil Naepflein <Emil.Naepflein@philosys.de>]

On Tue, 27 Mar 2001 10:46:25 +0200, Jörg-Oliver Todamm
<jtodamm@itc-consult.de> wrote:

> For me there are some points that I want to cover:
> - instant access to my video library, just as I have now to my music. I
> don't bother to wait some time until a MPEG4 is recompressed for
> viewing.

Ok.

> - I don't want to lose parts of this library due to a harddrive crash
> (Raid 5 is not an option due to the next reason)

What do you do if a tape, DVD-RW or CD isn't readable anymore?
Harddisks are so reliable today that I don't see a large problem here.
Anyway, one can just backup the stored movies from time to time onto
several CDs. As they are used only for backup multiple CDs are no
problem. And CDs are really cheap. 
With Raid5 you bring me to an idea. For 4x80 GB of Maxtor disks you need
an extra disk for Raid5. This disks costs but DM 600. Doing backup of
320 GB on CDs you need about 500 disks costing a similar amount. The
backup on CDs is a lot of work, so I would prefer the Raid5 solution.
They cost per GB stored can be improved further by using more than 4
data disks in the array. With todays disk reliability this should be no
problem.

> - a small and quiet box placed in my living room next to my TV and the
> HIFI components (harddiscs need some cooling and are loud)

Harddisks are relatively quiet today, but I understand your point. I
also want to minimize the noise in my living room. But I normally view a
projector and turned up volume so that the noise of any normal hd is
masked perfectly. ;-) The best would be to have a really small box in
the living room for playback and the server somewhere else.

> - connectivity has to be wireless (I use 11 Mbps WLAN, no wire could be
> placed in this room)

That's the biggest limitation. You cannot run a MPEG2 stream live over
WLAN without problems. The datarate has not enough reserves for the
varying speed of WLAN networks. Best would really be to connect
everything with 100BaseT.
But you can probably use the local disk as fast cache and a WLAN server
as primary storage.

> 
> So for me the future looks like that:
> - VDR as a front-end solution. It will record and playback the streams.
> Here I will use the largest discdrives if affordable (80GB is great, but
> my Samsung Spinpoint is cheap and quiet) 
> - A Server as back-end. Here I will store the majority of my movies and
> store them on tape, CD and so on. Here is also the chance to delete all
> the annoying commercials.

I am kind of undecided what I should do. On one side one central server
in the living room is easier to handle and cheaper if you want to
incorporate multiple SAT cards for multiple independend users and use
the resources efficiently. On the other side a client/server or
client/client structure is more clean and also somewhat fault tolerant.

It would be really nice to have a kind of distributed VDR which could
manage DVB cards and storage distributer over multiple nodes. ;-)

Emil


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