From c5eec1554942ef99bcf6b2065008fd3730121ec9 Mon Sep 17 00:00:00 2001
From: nu774 <honeycomb77@gmail.com>
Date: Wed, 30 Oct 2013 01:32:52 +0900
Subject: [PATCH] prepend 1 sample zero padding in case of SBR and enc_delay is
 odd

This is required because odd enc_delay cannot be exactly expressed in
downsampled scale, and HE-AACv2 FDK encoder actually has odd enc_delay.
---
 src/main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/main.c b/src/main.c
index d06c683..7d1a68f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -823,6 +823,16 @@ int main(int argc, char **argv)
         m4af_set_priming_mode(m4af, params.gapless_mode + 1);
         m4af_begin_write(m4af);
     }
+    if (sbr_mode && (aacinfo.encoderDelay & 1)) {
+        /*
+         * Since odd delay cannot be exactly expressed in downsampled scale,
+         * we push one zero frame to the encoder here, to make delay even
+         */
+        int16_t zero[8] = { 0 };
+        aacenc_result_t obuf = { 0 };
+        aac_encode_frame(encoder, sample_format, zero, 1, &obuf);
+        free(obuf.data);
+    }
     frame_count = encode(&params, reader, encoder, aacinfo.frameLength, m4af);
     if (frame_count < 0)
         goto END;
-- 
2.30.2