dvb: initial support on scanning symbolrates on dvb-c and set default symbolrate to 0

I think this should be optimised to rotate symbolrates only
when we get signal but were unable to tune channels.

This commit also causes that eta shows even more strange
times until it gets lock on some channel with correct
modulation/symbolrate.

modules/access/dvb/access.c

@@ -214,7 +214,7 @@ vlc_module_begin ()
     add_integer( "dvb-tone", -1, TONE_TEXT, TONE_LONGTEXT,
                  true )
     add_integer( "dvb-fec", 9, FEC_TEXT, FEC_LONGTEXT, true )
-    add_integer( "dvb-srate", 27500000, SRATE_TEXT, SRATE_LONGTEXT,
+    add_integer( "dvb-srate", 0, SRATE_TEXT, SRATE_LONGTEXT,
                  false )
     add_integer( "dvb-lnb-lof1", 0, LNB_LOF1_TEXT,
                  LNB_LOF1_LONGTEXT, true )
@@ -586,6 +586,9 @@ static block_t *BlockScan( access_t *p_access )
     if ( cfg.i_modulation )
         var_SetInteger( p_access, "dvb-modulation", cfg.i_modulation );
 
+    if ( cfg.i_symbolrate )
+        var_SetInteger( p_access, "dvb-srate", cfg.i_symbolrate );
+
     /* Setting frontend parameters for tuning the hardware */
     if( FrontendSet( p_access ) < 0 )
     {

modules/access/dvb/linux_dvb.c

@@ -435,6 +435,12 @@ static int ScanParametersDvbC( access_t *p_access, scan_parameter_t *p_scan )
         p_scan->i_modulation = 0;
     }
 
+    /* if user supplies symbolrate, don't scan those */
+    if( var_GetInteger( p_access, "dvb-srate" ) )
+        p_scan->b_symbolrate_set = true;
+    else
+        p_scan->b_symbolrate_set = false;
+
     /* */
     p_scan->bandwidth.i_min  = 6;
     p_scan->bandwidth.i_max  = 8;

modules/access/dvb/scan.c

@@ -555,22 +555,49 @@ int scan_Next( scan_t *p_scan, scan_configuration_t *p_cfg )
     }
 
     if( i_service == 0 &&
-        p_scan->parameter.type == SCAN_DVB_C &&
-        !p_scan->parameter.b_modulation_set )
+        p_scan->parameter.type == SCAN_DVB_C )
+    {
+        bool b_rotate=true;
+        if( !p_scan->parameter.b_modulation_set )
         {
             p_scan->parameter.i_modulation = (p_scan->parameter.i_modulation << 1 ) % 512;
             /* if we iterated all modulations, move on */
             if( !p_scan->parameter.i_modulation )
             {
                 p_scan->parameter.i_modulation = 16;
-            p_scan->i_index++;
+            } else {
+                b_rotate=false;
             }
             msg_Dbg( p_scan->p_obj, "modulation %d ", p_scan->parameter.i_modulation);
+        }
+        if( !p_scan->parameter.b_symbolrate_set )
+        {
+            /* symbol rates from dvb-tools dvb-c files */
+            static const unsigned short symbolrates[] = {
+             6900, 6875, 6950, 7000, 3450, 6111,
+             6428, 6952, 5900, 5000 };
+
+            enum { num_symbols = (sizeof(symbolrates)/sizeof(*symbolrates)) };
+
+            /* if we rotated modulations, rotate symbolrate */
+            if( b_rotate )
+               p_scan->parameter.i_symbolrate = (++p_scan->parameter.i_symbolrate % num_symbols );
+            p_cfg->i_symbolrate = 1000 * (symbolrates[ p_scan->parameter.i_symbolrate ] );
+            msg_Dbg( p_scan->p_obj, "symbolrate %d", p_cfg->i_symbolrate );
+            if( p_scan->parameter.i_symbolrate )
+                b_rotate=false;
+        }
+        if( b_rotate )
+            p_scan->i_index++;
     } else {
        p_scan->i_index++;
     }
     if( p_scan->parameter.type == SCAN_DVB_C )
+    {
        p_cfg->i_modulation = p_scan->parameter.i_modulation;
+       if( !p_cfg->i_symbolrate )
+           p_cfg->i_symbolrate = var_GetInteger( p_scan->p_obj, "dvb-srate" );
+    }
     return VLC_SUCCESS;
 }
 
@@ -1038,7 +1065,7 @@ block_t *scan_GetM3U( scan_t *p_scan )
         char *psz;
         if( asprintf( &psz, "#EXTINF:,,%s\n"
                         "#EXTVLCOPT:program=%d\n"
-                        "dvb://frequency=%d:bandwidth=%d:voltage=%d:fec=%d:modulation=%d\n"
+                        "dvb://frequency=%d:bandwidth=%d:voltage=%d:fec=%d:modulation=%d:srate=%d\n"
                         "\n",
                       s->psz_name && * s->psz_name ? s->psz_name : "Unknown",
                       s->i_program,
@@ -1046,7 +1073,8 @@ block_t *scan_GetM3U( scan_t *p_scan )
                       s->cfg.i_bandwidth,
                       s->cfg.c_polarization == 'H' ? 18 : 13,
                       s->cfg.i_fec,
-                      s->cfg.i_modulation ) < 0 )
+                      s->cfg.i_modulation,
+                      s->cfg.i_symbolrate ) < 0 )
             psz = NULL;
         if( psz )
         {

modules/access/dvb/scan.h

@@ -44,8 +44,10 @@ typedef struct scan_parameter_t
     bool b_use_nit;
     bool b_free_only;
     bool b_modulation_set;
+    bool b_symbolrate_set;
 
     int i_modulation;
+    int i_symbolrate;
     struct
     {
         int i_min;
@@ -85,6 +87,7 @@ typedef struct
     };
     int i_fec;
     int i_modulation;
+    int i_symbolrate;
     char c_polarization;
 } scan_configuration_t;