Re: MPE Question

[nurul <azila@nrg.cs.usm.my>]

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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