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Re: [Discuss-gnuradio] constant noutput_items
From: |
Michael Dickens |
Subject: |
Re: [Discuss-gnuradio] constant noutput_items |
Date: |
Wed, 28 Mar 2012 08:52:39 -0400 |
As Martin wrote, the shortest answer is: no, or, well, not really or not
always. Under some circumstances this could be made work at least sometimes,
but I don't think you can guarantee it all of the time. For example, many of
the OFDM blocks always process exactly 1 packet's or FFT's worth of data, and
hence have a guaranteed -actual- number of consumed and generated items; the
amount provided and requested by the scheduler may be different that the
actuals (and, I think, generally is). IIRC, the technique used by these blocks
is to set the I/O signatures, output multiple, and ::forecast such that the
number of I/O items is a multiple of what is required (the packet or FFT
length). In my (very limited) testing, the OFDM blocks work for their defaults
and sometimes other values; but they're not exactly robust -- some values just
don't work (and, no, I cannot given an example off the top of my head; just go
and play with the OFDM benchmarks). Good luck! - MLD
On Mar 28, 2012, at 5:43 AM, Martin Braun wrote:
> Short answer: no. Long answer: It depends. If you're depending on the input
> items. For a source, or for a block independent on the input data,
> there's ways to do this.
> Also, you can fix the output item size. Perhaps that'll do what you
> want (i.e. you can output vectors of fixed length).
> On Wed, Mar 28, 2012 at 08:58:37AM +0100, s k wrote:
>> I want to ask that can we immobilize the noutput_items value to a constant
>> value when we write a block. So we can give always the same amount of output.