@@ -256,11 +256,29 @@ av_cold struct FFIIRFilterState* ff_iir_filter_init_state(int order)

     }                                                                       \

 }

+#define FILTER_O2(type, fmt) {                                              \

+    int i;                                                                  \

+    const type *src0 = src;                                                 \

+    type       *dst0 = dst;                                                 \

+    for (i = 0; i < size; i++) {                                            \

+        float in = *src0   * c->gain  +                                     \

+                   s->x[0] * c->cy[0] +                                     \

+                   s->x[1] * c->cy[1];                                      \

+        CONV_##fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1])                \

+        s->x[0] = s->x[1];                                                  \

+        s->x[1] = in;                                                       \

+        src0 += sstep;                                                      \

+        dst0 += dstep;                                                      \

+    }                                                                       \

+}

+

 void ff_iir_filter(const struct FFIIRFilterCoeffs *c,

                    struct FFIIRFilterState *s, int size,

                    const int16_t *src, int sstep, int16_t *dst, int dstep)

 {

-    if (c->order == 4) {

+    if (c->order == 2) {

+        FILTER_O2(int16_t, S16)

+    } else if (c->order == 4) {

         FILTER_BW_O4(int16_t, S16)

     } else {

         FILTER_DIRECT_FORM_II(int16_t, S16)

@@ -271,7 +289,9 @@ void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *c,

                        struct FFIIRFilterState *s, int size,

                        const float *src, int sstep, float *dst, int dstep)

 {

-    if (c->order == 4) {

+    if (c->order == 2) {

+        FILTER_O2(float, FLT)

+    } else if (c->order == 4) {

         FILTER_BW_O4(float, FLT)

     } else {

         FILTER_DIRECT_FORM_II(float, FLT)