[opendtv] Re: wm trials at different telcos using wm series

  • From: Kon Wilms <kon@xxxxxxxxxxxx>
  • To: opendtv@xxxxxxxxxxxxx
  • Date: Tue, 17 May 2005 10:54:48 -0700

On Tue, 2005-05-17 at 23:01 +0530, Prashant Desai wrote:
>    I am curious , the list members views on the windows media server [ wm
> series ]  ,  is it a truly a carrier grade solution

I wouldn't call putting windows 2003 and windows media server on an off
the shelf server carrier grade. Try pulling the power plug and waiting
for the reboot and checkdisk, then having all the clients reconnect to
the box after a minute or two of downtime.

>   Does MS DRM can be used  for securing/encrypting ( CAS functionality )the
> live  Broadcast TV channels ? which can be decoded on the PC or on the set
> top box 

You can't do a full-blown CAS using the off-the-shelf MS DRM rights
manager and windows media server. There is no SMS integration for one.

DRM is file encryption and rights management. You're talking about pipe
encryption and entitlement management. These are two different things. 

> Running windows CE OS , if MS DRM cant be used for encryption of the live
> Broadcast TV channels then are there any other vendors who supports  wm9
> format 

Try any CA vendor? You're talking about pipe encryption. You don't need
to know or care what the underlying protocol is (although with the
fragmentation of large frames that windows media server/encoder does by
default, I can see this being an issue).

>  I  was just surprised when I came to know that windows media server is
> capable of supporting few 10 thousands of unicast streams simultaneously 
>  At the rate of  512 KBPS to  1MBPS  to 1.5 MBPS  for viewing the same on
> either PC or on TV sets. 

Why? You can do this one of two ways:

1. You just clone the socket for every unicast connection - you're
really reading the pre-encoded source file only once. Everything else is
an issue of the bus and network stack.
2. You load portions of the file/stream into buffered memory pools and
serve them 10,000 times. 10,000 memcpy functions wont even break a

Ofcourse both can go south really fast if a client has any network
issues and starts lagging to the end of the buffer (at which point you
need to drop him and restart the data flow). So you need to trade off
network reliability against the size of the buffer in seconds.

No rocket science there....


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