dvbv5-scan: Remove spurious transponder duplication

There's an algorithm to remove duplicated frequencies.
However, due to the zigzag tuning, the same channel
or transponder might appear with two different values.

Improves the code to also handle such case, by estimating
the needed bandwidth for each channel, and considering
any frequency shift bellow bandwitdh/8 as belonging to
the same channel/transponder.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/utils/dvb/dvbv5-scan.c b/utils/dvb/dvbv5-scan.c
index 8c454ae..030d153 100644 (file)
--- a/utils/dvb/dvbv5-scan.c
+++ b/utils/dvb/dvbv5-scan.c
@@ -185,18 +185,75 @@ static void add_new_freq(struct dvb_entry *entry, uint32_t freq)
 }
 
 static void add_other_freq_entries(struct dvb_file *dvb_file,
+                                   struct dvb_v5_fe_parms *parms,
                                   struct dvb_descriptors *dvb_desc)
 {
        int i;
-       uint32_t freq;
+       uint32_t freq, shift = 0, bw = 0, symbol_rate, ro;
+       int rolloff = 0;
 
        if (!dvb_desc->nit_table.frequency)
                return;
 
+       /* Need to handle only cable/satellite and ATSC standards */
+       switch (parms->current_sys) {
+       case SYS_DVBC_ANNEX_A:
+               rolloff = 115;
+               break;
+       case SYS_DVBC_ANNEX_C:
+               rolloff = 115;
+               break;
+       case SYS_DVBS:
+       case SYS_ISDBS: /* FIXME: not sure if this rollof is right for ISDB-S */
+               rolloff = 135;
+               break;
+       case SYS_DVBS2:
+       case SYS_DSS:
+       case SYS_TURBO:
+               dvb_fe_retrieve_parm(parms, DTV_ROLLOFF, &ro);
+               switch (ro) {
+               case ROLLOFF_20:
+                       rolloff = 120;
+                       break;
+               case ROLLOFF_25:
+                       rolloff = 125;
+                       break;
+               default:
+               case ROLLOFF_AUTO:
+               case ROLLOFF_35:
+                       rolloff = 135;
+                       break;
+               }
+               break;
+       case SYS_ATSC:
+       case SYS_DVBC_ANNEX_B:
+               bw = 6000000;
+               break;
+       default:
+               break;
+       }
+       if (rolloff) {
+               /*
+                * This is not 100% correct for DVB-S2, as there is a bw
+                * guard interval there but it should be enough for the
+                * purposes of estimating a max frequency shift here.
+                */
+               dvb_fe_retrieve_parm(parms, DTV_SYMBOL_RATE, &symbol_rate);
+               bw = (symbol_rate * rolloff) / 100;
+       }
+       if (!bw)
+               dvb_fe_retrieve_parm(parms, DTV_BANDWIDTH_HZ, &bw);
+
+       /*
+        * If the max frequency shift between two frequencies is below
+        * than the used bandwidth / 8, it should be the same channel.
+        */
+       shift = bw / 8;
+
        for (i = 0; i < dvb_desc->nit_table.frequency_len; i++) {
                freq = dvb_desc->nit_table.frequency[i];
 
-               if (new_freq_is_needed(dvb_file->first_entry, freq, 0))
+               if (new_freq_is_needed(dvb_file->first_entry, freq, shift))
                        add_new_freq(dvb_file->first_entry, freq);
        }
 }
@@ -336,7 +393,7 @@ static int run_scan(struct arguments *args,
                                  args->get_detected, args->get_nit);
 
                if (!args->dont_add_new_freqs)
-                       add_other_freq_entries(dvb_file, dvb_desc);
+                       add_other_freq_entries(dvb_file, parms, dvb_desc);
 
                free_dvb_ts_tables(dvb_desc);
        }