From a89f0c565d3410cfd9b266dd661a934408a01028 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Mon, 1 Aug 2016 19:53:23 +0200
Subject: [PATCH] Fix an issue with changing video bitrate when x264 speed
 control was in effect.

---
 x264_encoder.cpp       | 18 ++++++++++++------
 x264_speed_control.cpp |  3 +++
 x264_speed_control.h   | 14 ++++++++++++++
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/x264_encoder.cpp b/x264_encoder.cpp
index f77549d..9874519 100644
--- a/x264_encoder.cpp
+++ b/x264_encoder.cpp
@@ -249,12 +249,18 @@ void X264Encoder::encode_frame(X264Encoder::QueuedFrame qf)
 	// See if we have a new bitrate to change to.
 	unsigned new_rate = new_bitrate_kbit.exchange(0);  // Read and clear.
 	if (new_rate != 0) {
-		x264_param_t param;
-		x264_encoder_parameters(x264, &param);
-		param.rc.i_bitrate = new_rate;
-		update_vbv_settings(&param);
-		x264_encoder_reconfig(x264, &param);
-		printf("changing rate to %u\n", new_rate);
+		if (speed_control) {
+			speed_control->set_config_override_function([new_rate](x264_param_t *param) {
+				param->rc.i_bitrate = new_rate;
+				update_vbv_settings(param);
+			});
+		} else {
+			x264_param_t param;
+			x264_encoder_parameters(x264, &param);
+			param.rc.i_bitrate = new_rate;
+			update_vbv_settings(&param);
+			x264_encoder_reconfig(x264, &param);
+		}
 	}
 
 	if (speed_control) {
diff --git a/x264_speed_control.cpp b/x264_speed_control.cpp
index c6add3e..7eca74d 100644
--- a/x264_speed_control.cpp
+++ b/x264_speed_control.cpp
@@ -305,6 +305,9 @@ void X264SpeedControl::apply_preset(int new_preset)
 	p.analyse.b_mixed_references = s->mix;
 	p.analyse.i_direct_mv_pred = s->direct;
 	p.analyse.i_me_range = s->merange;
+	if (override_func) {
+		override_func(&p);
+	}
 	x264_encoder_reconfig(x264, &p);
 	preset = new_preset;
 }
diff --git a/x264_speed_control.h b/x264_speed_control.h
index 84eb090..7add8fd 100644
--- a/x264_speed_control.h
+++ b/x264_speed_control.h
@@ -47,6 +47,7 @@
 #include <stdint.h>
 #include <string.h>
 #include <math.h>
+#include <functional>
 
 extern "C" {
 #include "x264.h"
@@ -80,6 +81,17 @@ public:
 	void before_frame(float new_buffer_fill, int new_buffer_size, float f_uspf);
 	void after_frame();
 
+	// x264 seemingly has an issue where x264_encoder_reconfig() is not reflected
+	// immediately in x264_encoder_parameters(). Since speed control keeps calling
+	// those two all the time, any changes you make outside X264SpeedControl
+	// could be overridden. Thus, to make changes to encoder parameters, you should
+	// instead set a function here, which will be called every time parameters
+	// are modified.
+	void set_config_override_function(std::function<void(x264_param_t *)> override_func)
+	{
+		this->override_func = override_func;
+	}
+
 private:
 	void set_buffer_size(int new_buffer_size);
 	int dither_preset(float f);
@@ -112,4 +124,6 @@ private:
 		double avg_preset;
 		int den;
 	} stat;
+
+	std::function<void(x264_param_t *)> override_func = nullptr;
 };
-- 
2.39.2