From 5dd4ee6a6f9f9e58c354d2ba417ede2c65ec40ad Mon Sep 17 00:00:00 2001
From: Dominik Weckbecker <dominik.weckbecker@iis.fraunhofer.de>
Date: Wed, 24 Aug 2022 12:32:06 +0200
Subject: [PATCH] fix for issue 87: decoder crash for SBA with head tracking

---
 lib_com/options.h          |  3 +++
 lib_dec/ivas_output_init.c | 25 +++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/lib_com/options.h b/lib_com/options.h
index 98d71f99c3..434f8fef84 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -149,6 +149,9 @@
 
 #define LBR_SBA_CORE_CODING_TUNING                      /* Contribution "3 Core Coder Tuning for low bitrate SBA with 2 TCs" */ 
 
+
+#define FIX_I87                                         /*  fix for issue 86: incorrect Ambisonics order set for head rotation in SBA */
+
 /* ################## End DEVELOPMENT switches ######################### */
 /* clang-format on */
 #endif
diff --git a/lib_dec/ivas_output_init.c b/lib_dec/ivas_output_init.c
index 4398b3cb93..c21cbafda3 100644
--- a/lib_dec/ivas_output_init.c
+++ b/lib_dec/ivas_output_init.c
@@ -263,6 +263,10 @@ void ivas_renderer_select(
     AUDIO_CONFIG output_config;
     AUDIO_CONFIG transport_config;
 
+ #ifdef FIX_I87
+    int16_t nchan_internal;
+#endif
+
     renderer_type = &( st_ivas->renderer_type );
     internal_config = &( st_ivas->intern_config );
     output_config = st_ivas->hDecoderConfig->output_config;
@@ -355,6 +359,26 @@ void ivas_renderer_select(
 
             if ( st_ivas->hDecoderConfig->Opt_Headrotation )
             {
+
+#ifdef FIX_I87
+                nchan_internal = ivas_sba_get_nchan_metadata( st_ivas->sba_order );
+                if ( nchan_internal == 2 )
+                {
+                    st_ivas->hHeadTrackData->shd_rot_max_order = 1;
+                }
+                else if ( nchan_internal == 4 || nchan_internal == 3 )
+                {
+                    st_ivas->hHeadTrackData->shd_rot_max_order = 0;
+                }
+                else if ( nchan_internal == 6 || nchan_internal == 5 )
+                {
+                    st_ivas->hHeadTrackData->shd_rot_max_order = 2;
+                }
+                else if ( nchan_internal == 8 || nchan_internal == 7 )
+                {
+                    st_ivas->hHeadTrackData->shd_rot_max_order = 3;
+                }
+#else
                 if ( st_ivas->nchan_transport == 2 )
                 {
                     st_ivas->hHeadTrackData->shd_rot_max_order = 1;
@@ -371,6 +395,7 @@ void ivas_renderer_select(
                 {
                     st_ivas->hHeadTrackData->shd_rot_max_order = 3;
                 }
+#endif
             }
         }
         else if ( st_ivas->ivas_format == MC_FORMAT )
-- 
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