From b25021100436ada451cdd22e5a4d9a644d2bc3d7 Mon Sep 17 00:00:00 2001
From: Stefan Pöschel <github@basicmaster.de>
Date: Mon, 7 Aug 2017 23:48:00 +0200
Subject: AAC: skip PAD if only zero F-PAD

This optimizations saves four bytes if no X-PAD is present.
---
 src/odr-audioenc.cpp | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/odr-audioenc.cpp b/src/odr-audioenc.cpp
index 94e47cc..ff743bb 100644
--- a/src/odr-audioenc.cpp
+++ b/src/odr-audioenc.cpp
@@ -982,7 +982,18 @@ int main(int argc, char *argv[])
                     throw runtime_error(ss.str());
                 }
 
-                status |= STATUS_PAD_INSERTED;
+                /*
+                 * AAC: skip PAD if only zero F-PAD (saves four bytes)
+                 * See §5.4.3 in ETSI TS 102 563
+                 */
+                if (
+                		selected_encoder == encoder_selection_t::fdk_dabplus &&
+                		calculated_padlen == 2 &&
+						pad_buf[padlen - 2] == 0x00 &&
+						pad_buf[padlen - 1] == 0x00
+                ) {
+                	calculated_padlen = 0;
+                }
             }
             else {
                 // Some other error occurred during read.
@@ -990,6 +1001,8 @@ int main(int argc, char *argv[])
                 break;
             }
         }
+    	if (calculated_padlen)
+        	status |= STATUS_PAD_INSERTED;
 
 
         // -------------- Read Data
-- 
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