Re: [Discuss-gnuradio] Maximum input items consumed on each input stream

[Albin Stigö]

Laura et al,

consume_each <= ninput_items.

If you need a larger buffer than you consume you can abuse the
scheduler slightly by set_relative_rate(1, some_min_input_items), this
is done in the stream to vector blocks for example. I do this in a
visualization sink where I need to produce FFTs with a certain
overlap.

// We need at least this number of points to do our job
m_input_length = std::max<int>(m_consume_each, m_fft_size);
// This is probably abusing the scheduler quite a bit
set_relative_rate(1, m_input_length);

Interesting to see you work in neuroengineering. I'm an
anesthesiologist and very interested these applications of gnuradio.


--Albin

On Fri, Aug 30, 2019 at 11:44 AM Marcus Müller <address@hidden> wrote:
>
> Hi Laura,
>
> the buffer sizes are determined at flow graph startup based on the
> involved block's io signature, output multiples, alignment
> requirements, minimum and maximum buffer sizes, and the page size
> (which practically everywhere is 4kB).
>
> I think you're expecting the amount of items your block is presented
> with to be deterministic: it's simply not.
>
> It's a thing that depends on  the temporal execution of the signal
> processing flowgraph at run time. Thus, your work (or general_work)
> must always make sure it works within the boundaries of how many
> samples are supplied in that specific call, and how much output space
> is available at that point.
>
> I think
>
> https://www.gnuradio.org/blog/2017-01-05-buffers/
>
> might be of interest to you.
>
> Best regards,
> Marcus
>
> On Thu, 2019-08-29 at 14:27 -0700, Laura Arjona wrote:
> > Thank you very much Michael.
> >
> >  What are the I/O buffer sizes?
> >
> > * My block is a general block
> > * In my forecast: ninput_items_required[0] = noutput_items;
> > * In the general_work:  const gr_complex *in = (const gr_complex *)
> > input_items[0];
> >                                       float *out = (float *)
> > output_items[0];
> >
> > /*
> >      * The private constructor
> >      */
> >     decoder_impl::frame_decoder_impl(int sample_rate,std::vector<int>
> > output_sizes)
> >       : gr::block("decoder",
> >               gr::io_signature::make(1, 1, sizeof(gr_complex)),
> >               gr::io_signature::makev(2, 2, output_sizes)),
> >               s_rate(sample_rate)
> >     {
> >
> >
> >
> >
> > On Thu, Aug 29, 2019 at 5:41 AM Michael Dickens <
> > address@hidden> wrote:
> > > Hi Laura - In the "work" or "general_work" method, there are
> > > arguments that contain the information you're looking for. These
> > > arguments are set depending on what type of block you're creating
> > > (source, sink, sync, tagged_stream, whatever), are influenced by
> > > what the "forecast()" method returns, and are constrained by the
> > > I/O buffer sizes. Sorry to be a little vague, but the answer is
> > > that the value of the variable "consumed" in your description is
> > > context dependent. Hope this is useful! - MLD
> > >
> > > On Wed, Aug 28, 2019 at 2:53 PM Laura Arjona <address@hidden>
> > > wrote:
> > > > Hello GNURadio community,
> > > >
> > > > Does anyone know what is the maximum number of input items that
> > > > an Out Of Tree block can consume on each input stream?
> > > >
> > > > consume_each(consumed) --> what is the maximum value that the
> > > > variable consumed can take?
> > > >
> > > > Thank you very much.
> > > >
> > > >
> > > > --
> > > > Laura Arjona
> > > > Washington Research Foundation Innovation Postdoctoral Fellow in
> > > > Neuroengineering
> > > >
> > > > Paul G. Allen School of Computer Science & Engineering
> > > > 185 E Stevens Way NE
> > > > University of Washington
> > > > Seattle, WA 98195-2350
> > > > _______________________________________________
> > > > Discuss-gnuradio mailing list
> > > > address@hidden
> > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > >
> > >
> > > --
> > > Michael Dickens, Mac OS X Programmer
> > >
> > > Ettus Research Technical Support
> > >
> > > Email: address@hidden
> > >
> > > Web: http://www.ettus.com
> >
> >
> > _______________________________________________
> > Discuss-gnuradio mailing list
> > address@hidden
> > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
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