nbrx: make extra room for history in rx filter

[willcode]

The default output buffer allocation for the nb (noise blanker) block in nbrx could end up being smaller than the history requirement of the rx filter when filter params are adjusted at runtime. Allocate space for 64k items, which should be enough for a very tight filter.

Fixes #1233

[vladisslav2011]

I've tried this and it didn't work.

[willcode]

You ran this patch, or you've tried something like this before?

[vladisslav2011]

1. I've tried this before.
2. I've checked out the commit before my fix (direct implementation of the FIR filter) and added this one line.

It does not work at least on my system.

[willcode]

Since the quad rate is fixed at 96k and the filter widths are going to be the same, I'm not sure how we're seeing different results. What do you see if you add this to master? How much space did the error message say it was looking for?

[vladisslav2011]

Master does not compile, so I see nothing.
The error message with this fix:

gr::log :WARN: flat_flowgraph - Block (rx_nb_cc0) max output buffer set to 8192 instead of requested 65536

sched: <block fir_filter_ccc (45)> is requesting more input data
  than we can provide.
  ninput_items_required = 11570
  max_possible_items_available = 8191
  If this is a filter, consider reducing the number of taps.

[willcode]

What version of GR?

[vladisslav2011]

linux; GNU C++ version 7.3.0; Boost_106501; UHD_003.010.003.000-0-unknown

qt5ct: using qt5ct plugin
gr-osmosdr 0.1.5 (0.1.5) gnuradio 3.7.11

$ src/gqrx
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-vlad'
gr-osmosdr 0.2.0.0 (0.2.0) gnuradio v3.10.0.0-rc1-277-g463c3477

With this fix applied:

rx_nb_cc :warning: Block (rx_nb_cc0) max output buffer set to 23552 instead of requested 65536
rx_nb_cc :warning: Block (rx_nb_cc0) max output buffer set to 8192 instead of requested 23552
block_executor :error: sched: <block fir_filter_blk<IN_T,OUT_T,TAP_T> (130)> is requesting more input data  than we can provide.  ninput_items_required = 11570  max_possible_items_available = 8191  If this is a filter, consider reducing the number of taps.

And the bug is still here...
I'll update pull recent GNU Radio changes and retest, but it's highly unlikely, that it will work as there were no significant changes to the flat_flowgraph/block_detail...

*rebuilding current GNU Radio main in a Ubuntu 22.04 chroot.

[willcode]

No, it's going to be more complicated than this. The GR buffer allocator is not doing what I thought it would do.

[vladisslav2011]

Thing are getting more and more interesting here.
Gqrx segfaults when built with current GNU Radio main, so I can't test this at all...

[willcode]

Was it a segfault once after build, then worked after that? I've seen that occasionally and don't know what that is about. If it's a constant segfault, I haven't seen it.

[vladisslav2011]

The segfault is not related to this change.
I've made it work. That was HackRF and wrong gr-osmosdr branch without fixes.