From 16c71cac0d5c81e84271222d1ed0c501fe723d56 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Mon, 18 Apr 2016 19:35:18 +0200
Subject: [PATCH] Synchronize the Mux class, since both H264EncoderImpl and
 X264Encoder are writing to it (from different threads).

---
 mux.cpp | 15 +++++++++++----
 mux.h   |  5 ++++-
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/mux.cpp b/mux.cpp
index eff336f..534d56a 100644
--- a/mux.cpp
+++ b/mux.cpp
@@ -1,5 +1,6 @@
 #include <assert.h>
 
+#include <mutex>
 #include <string>
 #include <vector>
 
@@ -86,7 +87,10 @@ Mux::~Mux()
 void Mux::add_packet(const AVPacket &pkt, int64_t pts, int64_t dts)
 {
 	AVPacket pkt_copy;
-	av_copy_packet(&pkt_copy, &pkt);
+	if (av_copy_packet(&pkt_copy, &pkt) < 0) {
+		fprintf(stderr, "av_copy_packet() failed\n");
+		exit(1);
+	}
 	if (pkt.stream_index == 0) {
 		pkt_copy.pts = av_rescale_q(pts, AVRational{1, TIMEBASE}, avstream_video->time_base);
 		pkt_copy.dts = av_rescale_q(dts, AVRational{1, TIMEBASE}, avstream_video->time_base);
@@ -106,9 +110,12 @@ void Mux::add_packet(const AVPacket &pkt, int64_t pts, int64_t dts)
 		}
 	}
 
-	if (av_interleaved_write_frame(avctx, &pkt_copy) < 0) {
-		fprintf(stderr, "av_interleaved_write_frame() failed\n");
-		exit(1);
+	{
+		lock_guard<mutex> lock(ctx_mu);
+		if (av_interleaved_write_frame(avctx, &pkt_copy) < 0) {
+			fprintf(stderr, "av_interleaved_write_frame() failed\n");
+			exit(1);
+		}
 	}
 
 	av_packet_unref(&pkt_copy);
diff --git a/mux.h b/mux.h
index 2eb8eea..d645916 100644
--- a/mux.h
+++ b/mux.h
@@ -9,6 +9,8 @@ extern "C" {
 #include <libavformat/avio.h>
 }
 
+#include <mutex>
+
 class KeyFrameSignalReceiver {
 public:
 	// Needs to automatically turn the flag off again after actually receiving data.
@@ -28,7 +30,8 @@ public:
 	void add_packet(const AVPacket &pkt, int64_t pts, int64_t dts);
 
 private:
-	AVFormatContext *avctx;
+	std::mutex ctx_mu;
+	AVFormatContext *avctx;  // Protected by <ctx_mu>.
 	AVStream *avstream_video, *avstream_audio;
 	KeyFrameSignalReceiver *keyframe_signal_receiver;
 };
-- 
2.39.2