xbox display only supports rgba8

stepmania/src/BannerCache.cpp

@@ -233,9 +233,14 @@ struct BannerTexture: public RageTexture
 		/* Find a supported texture format.  If it happens to match the stored
 		 * file, we won't have to do any conversion here, and that'll happen often
 		 * with paletted images. */
+#if !defined(XBOX)
 		PixelFormat pf = m_pImage->format->BitsPerPixel == 8? PixelFormat_PAL: PixelFormat_RGB5A1;
 		if( !DISPLAY->SupportsTextureFormat(pf) )
 			pf = PixelFormat_RGBA4;
+#else
+		// xbox display currently supports only rgba8
+		PixelFormat pf = PixelFormat_RGBA8;
+#endif
 		ASSERT( DISPLAY->SupportsTextureFormat(pf) );
 
 		ASSERT(m_pImage);