[Discuss-gnuradio] atsc - field sync mux/demux questions

[Charles Swiger]

some questions toward porting GrAtscFieldSyncMux/Demux:

1) Is there a good concrete example for using 'forecast'?

it will be necessary since a FIELD SYNC field is (IIUC) a special
equalizer training and info field inserted every 312 data segments,
so the mux will take in 624 ds and output 626 ds.  Also is there
a "sampling frequency" to jack up by 313/312 like in the 0.9 version?

2) What is the 2.0 version of type VrSampleIndex  ?   Tracked it
back to

  typedef unsigned long long VrSampleIndex;

in VrTypes.h.  Maybe gr_uint64 from gr_types.h ?


There's (lots) more but I think using forecast is the thing to focus on
for now.


I see in gr_block.cc there's:

void
gr_block::forecast (int noutput_items, gr_vector_int
&ninput_items_required)
{
  unsigned ninputs = ninput_items_required.size ();
  for (unsigned i = 0; i < ninputs; i++)
    ninput_items_required[i] = noutput_items;
}


and in gr_sync_block.cc it's:

void
gr_sync_block::forecast (int noutput_items, gr_vector_int
&ninput_items_required)
{
  unsigned ninputs = ninput_items_required.size();
  for (unsigned i = 0; i < ninputs; i++)
    ninput_items_required[i] = fixed_rate_noutput_to_ninput
(noutput_items);
}




--Chuck