From 4b41f5983b5196589cb1ef6fa2bc0b93d28b8732 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Fri, 1 Apr 2016 10:34:32 +0200
Subject: [PATCH] Start a mux only on a keyframe, so that transcoding clients
 do not get too confused.

---
 httpd.cpp | 6 ++++++
 httpd.h   | 1 +
 2 files changed, 7 insertions(+)

diff --git a/httpd.cpp b/httpd.cpp
index b9b1d6f..6a92699 100644
--- a/httpd.cpp
+++ b/httpd.cpp
@@ -196,6 +196,12 @@ HTTPD::Mux::~Mux()
 
 void HTTPD::Mux::add_packet(const AVPacket &pkt, int64_t pts, int64_t dts)
 {
+	if (!seen_keyframe && !(pkt.stream_index == 0 && (pkt.flags & AV_PKT_FLAG_KEY))) {
+		// Wait until we see the first (video) key frame.
+		return;
+	}
+	seen_keyframe = true;
+
 	AVPacket pkt_copy;
 	av_copy_packet(&pkt_copy, &pkt);
 	if (pkt.stream_index == 0) {
diff --git a/httpd.h b/httpd.h
index e739f70..88aeecc 100644
--- a/httpd.h
+++ b/httpd.h
@@ -61,6 +61,7 @@ private:
 		void add_packet(const AVPacket &pkt, int64_t pts, int64_t dts);
 
 	private:
+		bool seen_keyframe = false;
 		AVFormatContext *avctx;
 		AVStream *avstream_video, *avstream_audio;
 	};
-- 
2.39.2