config: add min_fps_target setting

docs/source/about/advanced_usage.rst

@@ -409,6 +409,26 @@ dwmflush
 
       dwmflush = enabled
 
+min_fps_target
+^^^^^^^^^^^^^^
+
+**Description**
+   The minimum FPS Sunshine will attempt to maintain. Increasing this value slightly may help when streaming
+   mostly static content.
+
+   .. Warning:: Higher values will consume more bandwidth.
+
+**Default**
+   ``10``
+
+**Range**
+   ``1-240``
+
+**Example**
+   .. code-block:: text
+
+      min_fps_target = 10
+
 Audio
 -----
 

src/config.cpp

@@ -330,6 +330,7 @@ namespace config {
 
     0,  // hevc_mode
 
+    10,  // min_fps_target
     1,  // min_threads
     {
       "superfast"s,  // preset
@@ -957,6 +958,7 @@ namespace config {
     string_f(vars, "adapter_name", video.adapter_name);
     string_f(vars, "output_name", video.output_name);
     bool_f(vars, "dwmflush", video.dwmflush);
+    int_between_f(vars, "min_fps_target", video.min_fps_target, { 1, 240 });
 
     path_f(vars, "pkey", nvhttp.pkey);
     path_f(vars, "cert", nvhttp.cert);

src/config.h

@@ -15,6 +15,7 @@ namespace config {
 
     int hevc_mode;
 
+    int min_fps_target;  // Minimum fps target, determines minimum frame time
     int min_threads;  // Minimum number of threads/slices for CPU encoding
     struct {
       std::string sw_preset;

src/video.cpp

@@ -1311,6 +1311,10 @@ namespace video {
       return;
     }
 
+    // set minimum frame time, avoiding violation of client-requested target framerate
+    auto minimum_frame_time = std::chrono::milliseconds(1000 / std::min(config.framerate, config::video.min_fps_target));
+    BOOST_LOG(debug) << "Minimum frame time set to "sv << minimum_frame_time.count() << "ms, based on min fps target of "sv << std::min(config.framerate, config::video.min_fps_target) << "."sv;
+
     auto frame = session->device->frame;
 
     auto shutdown_event = mail->event<bool>(mail::shutdown);
@@ -1336,9 +1340,9 @@ namespace video {
         idr_events->pop();
       }
 
-      // Encode at a minimum of 10 FPS to avoid image quality issues with static content
+      // Encode at a minimum FPS to avoid image quality issues with static content
       if (!frame->key_frame || images->peek()) {
-        if (auto img = images->pop(100ms)) {
+        if (auto img = images->pop(minimum_frame_time)) {
           if (session->device->convert(*img)) {
             BOOST_LOG(error) << "Could not convert image"sv;
             return;

src_assets/common/assets/web/config.html

@@ -550,6 +550,22 @@ <h1 class="my-4">Configuration</h1>
           Disable if you encounter any VSync-related issues.
         </div>
       </div>
+      <!--min_fps_target-->
+      <div class="mb-3">
+        <label for="qp" class="form-label">Minimum FPS Target</label>
+        <input
+          type="number"
+          class="form-control"
+          id="min_fps_target"
+          placeholder="10"
+          v-model="config.min_fps_target"
+        />
+        <div class="form-text">
+          The minimum FPS Sunshine will attempt to maintain.<br />
+          Increasing this value slightly may help when streaming mostly static content.<br />
+          Higher values will consume more bandwidth.<br />
+        </div>
+      </div>
       <div class="mb-3 config-page" v-if="platform === 'linux'">
         <label for="output_name" class="form-label">Monitor number</label>
         <input
@@ -595,7 +611,7 @@ <h1 class="my-4">Configuration</h1>
           Quantization Parameter<br />
           Some devices may not support Constant Bit Rate.<br />
           For those devices, QP is used instead.<br />
-          Higher value means more compression, but less quality<br />
+          Higher value means more compression, but less quality.<br />
         </div>
       </div>
       <!-- Min Threads -->
@@ -983,6 +999,7 @@ <h1 class="my-4">Configuration</h1>
     "key_rightalt_to_key_win": "disabled",
     "keyboard": "enabled",
     "min_log_level": 2,
+    "min_fps_target": 10,
     "mouse": "enabled",
     "nv_coder": "auto",
     "nv_preset": "p4",