Closed Captions: spawn a decoder thread

We can't keep the cc decoder serialized with video decoder.
If the decoding delay between packetizer and video decoder is bigger
than caching (for example when using multi threaded decoder), we will
be too late for the next picture display while we wait for the right
rendering time for the CC.

Close #9049

src/input/decoder.c

@@ -466,8 +466,8 @@ int input_DecoderSetCcState( decoder_t *p_dec, bool b_decode, int i_channel )
         es_format_t fmt;
 
         es_format_Init( &fmt, SPU_ES, fcc[i_channel] );
-        p_cc = CreateDecoder( VLC_OBJECT(p_dec), p_owner->p_input, &fmt,
-                              false, p_owner->p_resource, p_owner->p_sout );
+        p_cc = input_DecoderNew( p_owner->p_input, &fmt,
+                              p_dec->p_owner->p_clock, p_owner->p_sout );
         if( !p_cc )
         {
             msg_Err( p_dec, "could not create decoder" );
@@ -478,7 +478,7 @@ int input_DecoderSetCcState( decoder_t *p_dec, bool b_decode, int i_channel )
         else if( !p_cc->p_module )
         {
             DecoderUnsupportedCodec( p_dec, fcc[i_channel] );
-            DeleteDecoder( p_cc );
+            input_DecoderDelete(p_cc);
             return VLC_EGENERIC;
         }
         p_cc->p_owner->p_clock = p_owner->p_clock;
@@ -497,10 +497,7 @@ int input_DecoderSetCcState( decoder_t *p_dec, bool b_decode, int i_channel )
         vlc_mutex_unlock( &p_owner->lock );
 
         if( p_cc )
-        {
-            module_unneed( p_cc, p_cc->p_module );
-            DeleteDecoder( p_cc );
-        }
+            input_DecoderDelete(p_cc);
     }
     return VLC_SUCCESS;
 }
@@ -1341,10 +1338,9 @@ static void DecoderGetCc( decoder_t *p_dec, decoder_t *p_dec_cc )
         if( !p_owner->cc.pp_decoder[i] )
             continue;
 
-        if( i_cc_decoder > 1 )
-            DecoderProcess( p_owner->cc.pp_decoder[i], block_Duplicate( p_cc ) );
-        else
-            DecoderProcess( p_owner->cc.pp_decoder[i], p_cc );
+        block_FifoPut( p_owner->cc.pp_decoder[i]->p_owner->p_fifo,
+            (i_cc_decoder > 1) ? block_Duplicate(p_cc) : p_cc);
+
         i_cc_decoder--;
         b_processed = true;
     }