RE: MPE Question

["Simon Teh" <chteh@nrg.cs.usm.my>]

Dear members,

For packing and padding, it depends on the TS packet. If a payload unit
finishes before the end of a TS packet payload, and where there is
sufficient space, the TS packet will carry one more new payload unit. 

So, TS packet padding and packing can be used for MPE and ULE.

I hope it will help.

Best Regards,
Simon Teh
Universiti Sains Malaysia

-----Original Message-----
From: owner-ipdvb@erg.abdn.ac.uk [mailto:owner-ipdvb@erg.abdn.ac.uk] On
Behalf Of nurul
Sent: 28 April 2005 13:43
To: ipdvb@erg.abdn.ac.uk
Subject: Re: MPE Question

Hi,

Do MPE allows packing? cause as far as i concern it's only allow padding
while ULE allows both. Correct me if i'm wrong.

regards,
nurul

On Thu, 2005-04-28 at 13:22, Bernhard Collini-Nocker wrote:
> Siva Veerepalli wrote:
> > A couple of questions about MPE-FEC framing.
> > 
> > 1. The interim IP datacast standard A079 (meant to
> > facilitate DVB-H trials) specifies that only one
> > datagram should be used per MPE section i.e., no
> > fragmentation of IP datagram over multiple MPE
> > sections. However, the DVB Databroadcast specification
> > allows fragmentation of the IP datagram over multiple
> > sections. Does anyone know what the usual practice is?
> 
> In order to reduce encapsulation overhead, section packing is used, i.e. 
> if the (remainder of an) IP packet does not fit exactly in a TS packet a 
> subsequent IP packet may start in that TS packet as well.
> In order to reduce jitter and latency, section packing is not used.
> 
> You can find both on existing services.
> 
> > Do the final DVB/IP datacast standards specify this
> > for DVB-H?
> 
> The difficulty with section peckaing on the transmit side is that the 
> encapsulator needs to wait for subsequent IP packets to fill an 
> partially filled TS packet and therefor has typically a time-out 
> associated to that waiting, ie before flushing the buffer and 
> transmitting the final TS packet.
> 
> > 2. The MPE section has optional stuffing bytes at the
> > end of the section. Are these used? If yes, for what?
> 
> Whenver an IP packets leaves "enough" space in the last TS packet 
> another IP packet could be inserted. If not wanted or needed, stuffing 
> takes care that the empty space is filled up with pattern 0xFF.
> 
> > thanks,
> > Siva
> > 
> > 
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