Let the value from --rate use the same code path than a value set at runtime.

It closes #4861.
It fixes playback when the rate cannot be respected (like with dvb/udp/...)
or need to be requested to the access_demux (rtsp).

src/input/input.c

@@ -370,13 +370,7 @@ static input_thread_t *Create( vlc_object_t *p_parent, input_item_t *p_item,
     p_input->p->title = NULL;
     p_input->p->i_title_offset = p_input->p->i_seekpoint_offset = 0;
     p_input->p->i_state = INIT_S;
-    double f_rate = var_InheritFloat( p_input, "rate" );
-    if( f_rate <= 0. )
-    {
-        msg_Warn( p_input, "Negative or zero rate values are forbidden" );
-        f_rate = 1.;
-    }
-    p_input->p->i_rate = INPUT_RATE_DEFAULT / f_rate;
+    p_input->p->i_rate = INPUT_RATE_DEFAULT;
     p_input->p->b_recording = false;
     memset( &p_input->p->bookmark, 0, sizeof(p_input->p->bookmark) );
     TAB_INIT( p_input->p->i_bookmark, p_input->p->pp_bookmark );
@@ -1290,6 +1284,13 @@ static int Init( input_thread_t * p_input )
         LoadSubtitles( p_input );
         LoadSlaves( p_input );
         InitPrograms( p_input );
+
+        double f_rate = var_InheritFloat( p_input, "rate" );
+        if( f_rate != 0.0 && f_rate != 1.0 )
+        {
+            vlc_value_t val = { .i_int = INPUT_RATE_DEFAULT / f_rate };
+            input_ControlPush( p_input, INPUT_CONTROL_SET_RATE, &val );
+        }
     }
 
     if( !p_input->b_preparsing && p_input->p->p_sout )

src/input/var.c

@@ -137,8 +137,6 @@ void input_ControlVarInit ( input_thread_t *p_input )
 
     /* Rate */
     var_Create( p_input, "rate", VLC_VAR_FLOAT | VLC_VAR_DOINHERIT );
-    val.f_float = (float)INPUT_RATE_DEFAULT / (float)p_input->p->i_rate;
-    var_Change( p_input, "rate", VLC_VAR_SETVALUE, &val, NULL );
 
     var_Create( p_input, "frame-next", VLC_VAR_VOID );