V210 issue fix + correct packing

internal/generator/v210.go

@@ -0,0 +1,20 @@
+package generator
+
+const v210RowAlignment = 128
+
+// V210ActiveLineSize returns the number of bytes containing pixel data in one
+// v210 row, including the final partial six-pixel block when needed.
+func V210ActiveLineSize(width int) int {
+	return (width + 5) / 6 * 16
+}
+
+// V210LineSize returns the MXL v210 row stride. MXL stores every row at a
+// 128-byte boundary, equivalent to rounding the width up to 48 pixels.
+func V210LineSize(width int) int {
+	return ((width + 47) / 48) * v210RowAlignment
+}
+
+// V210FrameSize returns the complete MXL payload size for a v210 frame.
+func V210FrameSize(width, height int) int {
+	return V210LineSize(width) * height
+}