Subject: Re: [AVT] Update (-09) of Timed Tex draft (WAS: RE: Comments ondraft-ietf-avt-rtp-3gpp-timed-text-08.txt)

From: Colin Perkins <[email-masked]>
Date: Sun, 1 May 2005 18:49:18 +0100

Jose,

On 13 Apr 2005, at 14:30, Jose Rey wrote:
...
>>> Right now, for TYPE 5 units applies:
>>>
>>>            o In general, TYPE 5 units MUST receive their
>> timestamp from
>>>              the first non-TYPE 5 unit following them in
>> the payload.
>>>            o However, if:
>>>
>>>
>>>    Rey & Matsui
>>  [Page 31]
>>> >    Internet Draft  Payload Format for 3GPP Timed Text   March 29, 
>>> 2005
>>>
>>>                o the payload only contains (one or several) TYPE 5
>>>                   units or,
>>>                o if one or several TYPE 5 units follow a sample of
>>>                   unknown duration (see Section 4.1.2, SDUR
>>> definition),
>>>
>>>              then (all) TYPE 5 units MUST use the RTP timestamp.
>>>
>>> Is this what you refer as too much complexity?
>>
>> Yes. Why not simply state that TYPE 5 units receive a
>> timestamp indicating when they become available for use?
>>
>
> This last sentence is included.  The other issue is where to place 
> them, i.e., currently they are placed as they are read from file. To 
> simplify one could say that they are all placed (regardless to which 
> unit in the payload they apply) at the beginning of the payload before 
> all other units and receive the RTP TS?

Sure, why not? As Dave said later, provided the sample descriptions 
have a suitable timestamp for (a) their position in the stream and (b) 
before the timestamp of the first AU that uses them, everything will 
work. The other rules seem to be unnecessary complexity.

Colin

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