swscale/input: fix rgba64 alpha non native

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit f3079858)
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/input.c

@@ -412,14 +412,24 @@ static void gbr24pToUV_half_c(uint8_t *_dstU, uint8_t *_dstV,
     }
 }
 
-static void rgba64ToA_c(uint8_t *_dst, const uint8_t *_src, const uint8_t *unused1,
-                        const uint8_t *unused2, int width, uint32_t *unused)
+static void rgba64leToA_c(uint8_t *_dst, const uint8_t *_src, const uint8_t *unused1,
+                          const uint8_t *unused2, int width, uint32_t *unused)
 {
     int16_t *dst = (int16_t *)_dst;
     const uint16_t *src = (const uint16_t *)_src;
     int i;
     for (i = 0; i < width; i++)
-        dst[i] = src[4 * i + 3];
+        dst[i] = AV_RL16(src + 4 * i + 3);
+}
+
+static void rgba64beToA_c(uint8_t *_dst, const uint8_t *_src, const uint8_t *unused1,
+                          const uint8_t *unused2, int width, uint32_t *unused)
+{
+    int16_t *dst = (int16_t *)_dst;
+    const uint16_t *src = (const uint16_t *)_src;
+    int i;
+    for (i = 0; i < width; i++)
+        dst[i] = AV_RB16(src + 4 * i + 3);
 }
 
 static void abgrToA_c(uint8_t *_dst, const uint8_t *src, const uint8_t *unused1, const uint8_t *unused2, int width, uint32_t *unused)
@@ -1359,9 +1369,9 @@ av_cold void ff_sws_init_input_funcs(SwsContext *c)
         }
         switch (srcFormat) {
         case AV_PIX_FMT_BGRA64LE:
+        case AV_PIX_FMT_RGBA64LE:  c->alpToYV12 = rgba64leToA_c; break;
         case AV_PIX_FMT_BGRA64BE:
-        case AV_PIX_FMT_RGBA64LE:
-        case AV_PIX_FMT_RGBA64BE:  c->alpToYV12 = rgba64ToA_c; break;
+        case AV_PIX_FMT_RGBA64BE:  c->alpToYV12 = rgba64beToA_c; break;
         case AV_PIX_FMT_BGRA:
         case AV_PIX_FMT_RGBA:
             c->alpToYV12 = rgbaToA_c;