From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: ValdikSS <iam@valdikss.org.ru>
Date: Thu, 13 Sep 2018 23:14:10 +0300
Subject: [PATCH] Allow using alternative (higher) SBC HD bitrates with a
 property

Change-Id: Ic85e5c8a8c70233de2125e69c01d74e5501a2da8
---
 stack/a2dp/a2dp_sbc_encoder.cc | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/stack/a2dp/a2dp_sbc_encoder.cc b/stack/a2dp/a2dp_sbc_encoder.cc
index d80f1b680..5cf1ac104 100644
--- a/stack/a2dp/a2dp_sbc_encoder.cc
+++ b/stack/a2dp/a2dp_sbc_encoder.cc
@@ -32,6 +32,7 @@
 #include "embdrv/sbc/encoder/include/sbc_encoder.h"
 #include "osi/include/log.h"
 #include "osi/include/osi.h"
+#include "osi/include/properties.h"
 
 /* Buffer pool */
 #define A2DP_SBC_BUFFER_SIZE BT_DEFAULT_BUFFER_SIZE
@@ -54,6 +55,17 @@
 #define A2DP_SBC_3DH5_DEFAULT_BITRATE 552
 #define A2DP_SBC_3DH5_48KHZ_BITRATE 601
 
+/*
+ * SBC Dual Channel (SBC HD) 2DH5 alternative bitrates.
+ * 648 kbps @ 48 khz, 595.4 kbps @ 44.1 khz.
+ * Up to 3 frames for 2DH5.
+ */
+#define A2DP_SBC_2DH5_ALT_BITRATE 596
+#define A2DP_SBC_2DH5_ALT_48KHZ_BITRATE 649
+
+// SBC HD alternative bitrate property
+#define A2DP_SBC_HD_PROP "persist.bluetooth.sbc_hd_higher_bitrate"
+
 #define A2DP_SBC_NON_EDR_MAX_RATE 229
 
 /*
@@ -853,6 +865,7 @@ static uint16_t a2dp_sbc_source_rate() {
   if (a2dp_sbc_encoder_cb.sbc_encoder_params.s16SamplingFreq == SBC_sf48000)
     rate = A2DP_SBC_48KHZ_BITRATE;
 
+  /* 3DH5 maximum bitrates */
   if (a2dp_sbc_encoder_cb.peer_supports_3mbps &&
       a2dp_sbc_encoder_cb.TxAaMtuSize >= MIN_3MBPS_AVDTP_SAFE_MTU) {
     rate = A2DP_SBC_3DH5_DEFAULT_BITRATE;
@@ -860,6 +873,14 @@ static uint16_t a2dp_sbc_source_rate() {
       rate = A2DP_SBC_3DH5_48KHZ_BITRATE;
   }
 
+  /* 2DH5 alternative bitrates */
+  if (!a2dp_sbc_encoder_cb.peer_supports_3mbps &&
+      osi_property_get_int32(A2DP_SBC_HD_PROP, 0)) {
+    rate = A2DP_SBC_2DH5_ALT_BITRATE;
+    if (a2dp_sbc_encoder_cb.sbc_encoder_params.s16SamplingFreq == SBC_sf48000)
+      rate = A2DP_SBC_2DH5_ALT_48KHZ_BITRATE;
+  }
+
   /* restrict bitrate if a2dp link is non-edr */
   if (!a2dp_sbc_encoder_cb.is_peer_edr) {
     rate = A2DP_SBC_NON_EDR_MAX_RATE;