Re: [Discuss-gnuradio] Setting the noutput_items variable in a tagged_stream_block

[Martin Braun]

On 04/02/2016 05:22 PM, Gonzalo Arcos wrote:
> The problem i am facing is that when work() is called for the ofdm
> carrier allocator, the value of the parameter *noutput_items *has
> nothing to do with the number returned
> by *calculate_output_stream_length. *I was expecting for it to be the
> same, since as far as i understand that is the use of the
> calculate_output_stream_length function, to determine how many
> outputItems i will have when executing the work function for a given
> number of input items.. 

No, noutput_items is the size of the output buffers. It will be >= the
result of calculate_output_stream_length().

> The number that comes in the parameter *noutput_items *when work is
> called, is always half of the number set in the Min Ouput Buffer
> variable for that block, which is visible from GNU Radio Companion. If i
> set 0 there, then the default buffer size is used. 
> The problem that i am facing is that the default value is not always big
> enough, and in these cases the flowgraph wont work. However, i do not
> want to assign an excessively high value for the buffer if i am not
> gonna use it, that is why i need to dynamically change
> the *noutput_items *based on the number of input items, which is exactly
> what *calculate_output_stream_length *is supposed to do!

calculate_output_stream_length() is an inverse forecast(), if you like.
noutput_items depends in the buffer sizes. Those are not related. In
fact, if you have too small buffers, you can't use tagged streams at all.

Not sure if this is what you were asking. Was it?

M

> Any ideas why i am experiencing this behavior from GNU Radio?
> 
> Thanks in advance.
> 
> 
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