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



Jose,

On 2 May 2005, at 09:49, Jose Rey wrote:
...
Note that sending a sample description together with every text sample
(or set of samples) may result in a situation where the same sample
description is present in the receiver buffer many times, but with
different timestamp values. This is a desing choice to ensure correct
reception of sample descriptions and may cause moderate overhead.

I'm not sure this part's appropriate, since it assumes a particular receiver buffer implementation strategy.

I am assuming that only the basic functionality is implemented: opening RTP packets, reading out units, giving them a TS as the rules describe and storing them in the receiver buffer in TS order. I intended to be as general as possible. The last sentence may lead to misunderstanding. Instead of that one, maybe describing an easy way to avoid this situation is more helpful:


"Note that sending a sample description together with every text sample (or set of samples) may result in a situation where the same sample description is present in the receiver buffer many times, but with different timestamp values. This can be avoided by maintaining a list of currently stored sample descriptions (i.e., their SIDX values) and checking this before writing in the buffer."

This still has the same problem: it talks about implementation strategies for the receiver buffer. From the point of the payload format, we don't care how many copies of the data are maintained in the buffer, or how you remove duplicates.


Colin


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