feat: double buffered video input

default/frag2.glsl

@@ -2,8 +2,8 @@
 
 // VIDEO 2
 // -----------
-// IN: 2 (RAW IN B)
-// OUT: 4 (IN B)
+// IN: 2+4 (RAW IN B)
+// OUT: 6 (IN B)
 
 in vec2 vUV;
 out vec4 fragColor;
@@ -12,14 +12,18 @@ out vec4 fragColor;
 
 uniform sampler2D iTex0;
 uniform sampler2D iTex2;
+uniform sampler2D iTex4;
 uniform int iInputFormat2;
+uniform int iInputSwap2;
 uniform vec2 iInputResolution2;
 
 void main() {
     if (iInputFormat2 == YUYV_FOURCC) {
-        fragColor = yuyvTex(iTex2, vUV, int(iInputResolution2.x));
-    } else if (iInputResolution2.x > 0) {
-        fragColor = texture(iTex2, vUV);
+        if (iInputSwap2 > 0) {
+            fragColor = yuyvTex(iTex4, vUV, int(iInputResolution2.x));
+        } else {
+            fragColor = yuyvTex(iTex2, vUV, int(iInputResolution2.x));
+        }
     } else {
         fragColor = texture(iTex0, vUV);
     }