From dd44db0c1171be2163e692ec0dddb1b47832239e Mon Sep 17 00:00:00 2001
From: ronag <ronag89@gmail.com>
Date: Fri, 17 Aug 2018 15:29:32 +0200
Subject: [PATCH] fix(ffmpeg): don't underflow while pre-rolling

---
 src/modules/ffmpeg/producer/av_producer.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/modules/ffmpeg/producer/av_producer.cpp b/src/modules/ffmpeg/producer/av_producer.cpp
index 35a37c2b6b..4dde599d26 100644
--- a/src/modules/ffmpeg/producer/av_producer.cpp
+++ b/src/modules/ffmpeg/producer/av_producer.cpp
@@ -673,10 +673,11 @@ struct AVProducer::Impl
         if (buffer_.empty() || (frame_flush_ && buffer_.size() < 4) || (prerolling_ && buffer_.size() < buffer_capacity_ / 4)) {
             if (buffer_eof_) {
                 return frame_;
-            } else {
+            }
+            if (!prerolling_) {
                 graph_->set_tag(diagnostics::tag_severity::WARNING, "underflow");
-                return core::draw_frame{};
             }
+            return core::draw_frame{};
         }
 
         auto frame  = core::draw_frame(make_frame(this, *frame_factory_, buffer_[0].video, buffer_[0].audio));