Add FIR function to filter discrete blocks, for SECAM

fir.c

@@ -275,6 +275,25 @@ size_t fir_int16_process(fir_int16_t *s, int16_t *out, const int16_t *in, size_t
 	return(x);
 }
 
+size_t fir_int16_process_block(fir_int16_t *s, int16_t *out, const int16_t *in, size_t samples)
+{
+	int x;
+
+	/* Pre-fill buffer */
+	memset(s->win, 0, (s->lwin + s->ataps) * sizeof(int16_t));
+	s->owin = 0;
+
+	for(s->owin = 0; s->owin < s->ataps / 2; s->owin++, in += 2)
+	{
+		s->win[s->owin] = *in;
+		if(s->owin < s->ataps) s->win[s->owin + s->lwin] = *in;
+	}
+
+	x = fir_int16_process(s, out, in, samples);
+
+	return(x);
+}
+
 void fir_int16_free(fir_int16_t *s)
 {
 	free(s->win);

fir.h

@@ -62,6 +62,7 @@ extern void fir_complex_band_pass(double *taps, size_t ntaps, double sample_rate
 
 extern int fir_int16_init(fir_int16_t *s, const double *taps, unsigned int ntaps, int interpolation, int decimation, int delay);
 extern size_t fir_int16_process(fir_int16_t *s, int16_t *out, const int16_t *in, size_t samples);
+extern size_t fir_int16_process_block(fir_int16_t *s, int16_t *out, const int16_t *in, size_t samples);
 extern void fir_int16_free(fir_int16_t *s);
 
 extern int fir_int16_resampler_init(fir_int16_t *s, int interpolation, int decimation);

video.c

@@ -2787,9 +2787,8 @@ static int _vid_next_line_raster(vid_t *s, void *arg, int nlines, vid_line_t **l
 			}
 		}
 
-		x = s->fm_secam_fir.ntaps / 2;
-		fir_int16_process(&s->secam_l_fir, l->output + (s->active_left - x) * 2, l->output + (s->active_left) * 2, s->active_width - x);
-		fir_int16_process(&s->fm_secam_fir, l->output + 1, l->output + 1 + x * 2, s->width - x);
+		fir_int16_process_block(&s->secam_l_fir, l->output + s->active_left * 2, l->output + s->active_left * 2, s->active_width);
+		fir_int16_process_block(&s->fm_secam_fir, l->output + 1, l->output + 1, s->width);
 		iir_int16_process(&s->fm_secam_iir, l->output + 1, l->output + 1, s->width, 2);
 
 		/* Limit the FM deviation */