From 460a45268b4c6ecfb12d5f6c518ecde70c6a0549 Mon Sep 17 00:00:00 2001
From: Cameron Gutman <aicommander@gmail.com>
Date: Mon, 20 Jan 2020 17:23:57 -0800
Subject: [PATCH] Change threads option to min_threads

---
 assets/sunshine.conf | 7 +++++--
 sunshine/config.cpp  | 4 ++--
 sunshine/config.h    | 2 +-
 sunshine/video.cpp   | 8 +++++---
 4 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/assets/sunshine.conf b/assets/sunshine.conf
index ef96f52f..6b316a76 100644
--- a/assets/sunshine.conf
+++ b/assets/sunshine.conf
@@ -80,8 +80,11 @@ crf = 0
 # If crf != 0, then this parameter is ignored
 qp = 28
 
-# Number of threads used by ffmpeg to encode the video
-threads = 8
+# Minimum number of threads used by ffmpeg to encode the video.
+# Increasing the value slightly reduces encoding efficiency, but the tradeoff is usually
+# worth it to gain the use of more CPU cores for encoding. The ideal value is the lowest
+# value that can reliably encode at your desired streaming settings on your hardware.
+min_threads = 2
 
 # Allows the client to request HEVC Main or HEVC Main10 video streams.
 # HEVC is more CPU-intensive to encode, so enabling this may reduce performance.
diff --git a/sunshine/config.cpp b/sunshine/config.cpp
index 444cd16c..8db697d8 100644
--- a/sunshine/config.cpp
+++ b/sunshine/config.cpp
@@ -19,7 +19,7 @@ video_t video {
   35, // crf
   35, // qp
 
-  4, // threads
+  2, // min_threads
 
   0, // hevc_mode
   "superfast"s, // preset
@@ -156,7 +156,7 @@ void parse_file(const char *file) {
 
   int_f(vars, "crf", video.crf);
   int_f(vars, "qp", video.qp);
-  int_f(vars, "threads", video.threads);
+  int_f(vars, "min_threads", video.min_threads);
   int_between_f(vars, "hevc_mode", video.hevc_mode, {
     0, 2
   });
diff --git a/sunshine/config.h b/sunshine/config.h
index c55b5c85..541d8727 100644
--- a/sunshine/config.h
+++ b/sunshine/config.h
@@ -10,7 +10,7 @@ struct video_t {
   int crf; // higher == more compression and less quality
   int qp; // higher == more compression and less quality, ignored if crf != 0
 
-  int threads; // Number threads used by ffmpeg
+  int min_threads; // Minimum number of threads/slices for CPU encoding
 
   int hevc_mode;
   std::string preset;
diff --git a/sunshine/video.cpp b/sunshine/video.cpp
index d8cd84aa..be9652c7 100644
--- a/sunshine/video.cpp
+++ b/sunshine/video.cpp
@@ -165,10 +165,12 @@ void encodeThread(
   // Some client decoders have limits on the number of reference frames
   ctx->refs = config.numRefFrames;
 
-  ctx->slices = config.slicesPerFrame;
+  // Clients will request for the fewest slices per frame to get the
+  // most efficient encode, but we may want to provide more slices than
+  // requested to ensure we have enough parallelism for good performance.
+  ctx->slices = std::max(config.slicesPerFrame, config::video.min_threads);
   ctx->thread_type = FF_THREAD_SLICE;
-  ctx->thread_count = std::min(ctx->slices, config::video.threads);
-
+  ctx->thread_count = ctx->slices;
 
   AVDictionary *options {nullptr};
   av_dict_set(&options, "preset", config::video.preset.c_str(), 0);