Re: ULE-01 : last byte(s) precision

[Mahesh Sooriyabandara <mahesh@erg.abdn.ac.uk>]

Alain,

It's a good question!
Clearly we need more text:

There are three concerns on the use of unused bytes in a TS-packet.

(i) No PP (i.e. when PUSI =0) and 1 B remaining (this is fixed in ULE
-01, i.e. by skipping is there is <2B remaining).
If PP is not set, the remaining one byte can not be used for packing in
any case.
But if PP is set and use of remaining 1 byte for packing depends on
whether splitting of "end indicator" (case ii) and/or " length field"
(case iii)
is allowed.

(ii) No split "end indicator" if we skip when {0,1} bytes remaining (as
in ULE -01, i.e. by skipping is there is <2B remaining).

(iii) No split Length field if {0,1,2} bytes when PUSI set and {0,1,2,3)

bytes when PUSI was not originally set. That would mean skipping if
there is <4B remaining!

A discussion on each of the three cases should help resolve the
ambiguity in
the current text.

Adding another example is a good idea anyway - we first need to decide
if
this is OPTIONAL or REQUIRED behaviour.

 -Mahesh

alain.ritoux@6wind.com wrote:

> OK, the PP using the last available byte has been cleared !
> And there are no more case with the lenght/end_inidcator
> being split over 2 TS cells, but ...
>
> 5.3 != 5.3.1
> "If there is at least two remaining bytes ...."
> "... and a TS packet has more than two bytes of unused payload"
>
> so >2 or >=2 ?
>
> so if there is 2 bytes left, and a PP not already set, I see
> it has to start on a next TS cell, but if the PP is already set,
> does the new SNDU start in the same TS packet ? From the exemple
> A.2 (SNDU D) I would think yes, but from the text I have a doubt.
>
> More over in the exemple section a case should be shown, that packing
> with a PP creation is not done when there is only two bytes left, for
> it would split the length, this can be shown with in the exemple A.2
>    SNDU D : 184 bytes (instead of 185)
>    SNDU E , which lead to :
>
>            ....
>                    PP=0
>            +-----+------+------+-   -+------+------+------+
>            | HDR | 0x00 | C000 | ... | C180 | D000 | D001 |
>            +-----+---*--+-*----+-   -+------+------+------+
>            PUSI=1    *    *
>                      ******
>                                       End Indicator
>            +-----+------+-   -+------+------+------+
>            | HDR | D002 | ... | D183 | 0xFF | 0xFF |
>            +-----+------+-   -+------+------+------+
>             PUSI=0
>
>                     PP=0
>            +-----+------+------+-
>            | HDR | 0x00 | E000 | ...
>            +-----+---*--+-*----+-
>            PUSI=1    *    *
>                      ******
>
> Your thoughts ?
>
> Best wishes.
> Alain.
> --
> Alain RITOUX
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