diff --git a/libswscale/ops.c b/libswscale/ops.c
index c993e9eb58..e2b6da25a8 100644
--- a/libswscale/ops.c
+++ b/libswscale/ops.c
@@ -133,6 +133,38 @@ const char *ff_sws_op_type_name(SwsOpType op)
     return "ERR";
 }
 
+SwsCompMask ff_sws_comp_mask_q4(const AVRational q[4])
+{
+    SwsCompMask mask = 0;
+    for (int i = 0; i < 4; i++) {
+        if (q[i].den)
+            mask |= SWS_COMP(i);
+    }
+    return mask;
+}
+
+SwsCompMask ff_sws_comp_mask_swizzle(const SwsCompMask mask, const SwsSwizzleOp swiz)
+{
+    SwsCompMask res = 0;
+    for (int i = 0; i < 4; i++) {
+        const int src = swiz.in[i];
+        if (SWS_COMP_TEST(mask, src))
+            res |= SWS_COMP(i);
+    }
+
+    return res;
+}
+
+SwsCompMask ff_sws_comp_mask_needed(const SwsOp *op)
+{
+    SwsCompMask mask = 0;
+    for (int i = 0; i < 4; i++) {
+        if (SWS_OP_NEEDED(op, i))
+            mask |= SWS_COMP(i);
+    }
+    return mask;
+}
+
 /* biased towards `a` */
 static AVRational av_min_q(AVRational a, AVRational b)
 {
diff --git a/libswscale/ops.h b/libswscale/ops.h
index c1723dfc6a..fb5b9fab4e 100644
--- a/libswscale/ops.h
+++ b/libswscale/ops.h
@@ -78,6 +78,27 @@ typedef enum SwsOpType {
 
 const char *ff_sws_op_type_name(SwsOpType op);
 
+/**
+ * Bit-mask of components. Exact meaning depends on the usage context.
+ */
+typedef uint8_t SwsCompMask;
+enum {
+    SWS_COMP_NONE = 0,
+    SWS_COMP_ALL  = 0xF,
+#define SWS_COMP(X) (1 << (X))
+#define SWS_COMP_TEST(mask, X) (!!((mask) & SWS_COMP(X)))
+#define SWS_COMP_INV(mask) ((mask) ^ SWS_COMP_ALL)
+#define SWS_COMP_ELEMS(N) ((1 << (N)) - 1)
+#define SWS_COMP_MASK(X, Y, Z, W)   \
+    (((X) ? SWS_COMP(0) : 0) |      \
+     ((Y) ? SWS_COMP(1) : 0) |      \
+     ((Z) ? SWS_COMP(2) : 0) |      \
+     ((W) ? SWS_COMP(3) : 0))
+};
+
+/* Compute SwsCompMask from values with denominator != 0 */
+SwsCompMask ff_sws_comp_mask_q4(const AVRational q[4]);
+
 typedef enum SwsCompFlags {
     SWS_COMP_GARBAGE = 1 << 0, /* contents are undefined / garbage data */
     SWS_COMP_EXACT   = 1 << 1, /* value is an exact integer */
@@ -85,8 +106,6 @@ typedef enum SwsCompFlags {
     SWS_COMP_SWAPPED = 1 << 3, /* byte order is swapped */
 } SwsCompFlags;
 
-#define SWS_OP_NEEDED(op, idx) (!((op)->comps.flags[idx] & SWS_COMP_GARBAGE))
-
 typedef struct SwsComps {
     SwsCompFlags flags[4]; /* knowledge about (output) component contents */
     bool unused[4]; /* which input components are definitely unused */
@@ -141,6 +160,7 @@ typedef struct SwsSwizzleOp {
 } SwsSwizzleOp;
 
 #define SWS_SWIZZLE(X,Y,Z,W) ((SwsSwizzleOp) { .in = {X, Y, Z, W} })
+SwsCompMask ff_sws_comp_mask_swizzle(SwsCompMask mask, SwsSwizzleOp swiz);
 
 typedef struct SwsShiftOp {
     uint8_t amount; /* number of bits to shift */
@@ -242,6 +262,11 @@ typedef struct SwsOp {
     SwsComps comps;
 } SwsOp;
 
+#define SWS_OP_NEEDED(op, idx) (!((op)->comps.flags[idx] & SWS_COMP_GARBAGE))
+
+/* Compute SwsCompMask from a mask of needed components */
+SwsCompMask ff_sws_comp_mask_needed(const SwsOp *op);
+
 /**
  * Describe an operation in human-readable form.
  */