[Discuss-gnuradio] stream tagging at iregular periods of time

[Jorge Gallo]

Hello,

 

I am a little confused about stream tagging. I read in the documentation that one tag can be appended to any sample in the data stream so it can be something that happens once in a while and it doesn't have to be at regular intervals. That is pretty useful.

 

Then, when reading about Tagged Stream Blocks it says:

 

"On the first item of a streamed PDU, there must be a tag with a specific key, which stores the length of the PDU as a PMT integer. If anything else, or no tag, is on this first item, this will cause the flow graph to crash!".

 

Is it only for the first item or is it PDU after PDU? I mean, a new tag with the key and length must arrive immediately after one whole PDU is completed?

If the answer is “yes” I understand it like a vector streaming. What is the difference? Then, when is stream tagging useful? I don’t get that from the documentation.

 

What if my custom burst each of them identified with a tag come at non-defined periods of time? Do I have to develop the block as a basic/sync block that read tags of each sample instead and forget about tagged stream blocks?

 

Many thanks in advance. This is a really good community!

Jorge.

 

 

PS: At the beginning I found confusing that a Tagged File Sink is not a Tagged Stream Block given its name but it is only my personal opinion