fix: restore 4K integer mode; drop 3.6K preset; clarify bitrate

Keep fractional NTSC out of 4K launch mode to avoid C5 black screen,
remove the 3.6K resolution preset now that native 4K is the path, and
document that bitrates above 250 Mbps rarely help and can increase loss.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: GuiDev1994

README.md

@@ -7,9 +7,9 @@ Unofficial fork of [Moonlight TV](https://github.com/mariotaku/moonlight-tv) for
 ## Highlights
 
 - **AMOLED layout** — pure black background, dark surfaces, violet accent.
-- **3.6K (3584×2016)** — between 2K and 4K; strong quality with less decoder load than native 4K.
+- **Native 4K (3840×2160)** streaming with HDR10 when supported.
 - **HDR10 (PQ)** over HEVC Main10 (when supported).
-- Up to **300 Mbps** bitrate; **~270 Mbps** is a practical ceiling on stable 5 GHz Wi‑Fi for 3.6K HDR 120 Hz.
+- Bitrate slider up to **300 Mbps**; above **250 Mbps** there is usually no visible gain and packet loss becomes more likely as the link becomes less stable.
 - **Performance stats overlay**, **full on-screen keyboard**, and **virtual mouse** during streaming.
 
 ## Screenshots
@@ -28,10 +28,10 @@ Unofficial fork of [Moonlight TV](https://github.com/mariotaku/moonlight-tv) for
 
 | Setting | Suggestion |
 |---------|------------|
-| Resolution | **3.6K** (3584×2016) |
+| Resolution | **4K** (3840×2160) |
 | FPS | 60 or 120 |
 | Codec | HEVC (H.265) |
-| Bitrate | Start at **120–180 Mbps**; raise toward **~270 Mbps** on a stable link |
+| Bitrate | Start at **120–180 Mbps**; stay at or below **250 Mbps** for a stable link. Higher values rarely help and can increase packet loss. |
 
 ## Streaming controls
 

core/libgamestream/src/client.c

@@ -488,9 +488,14 @@ static void append_launch_mode_param(char *url, size_t url_len, int width, int h
                                      int client_refresh_x100, bool is_gfe) {
     /* Apollo and several Sunshine forks parse the third mode component with atof() and
      * store refresh rate in millihertz (119.88 -> 119880). Sending an integer (120) makes
-     * them run at exactly 120 Hz even when clientRefreshRateX100 carries 11988. */
+     * them run at exactly 120 Hz even when clientRefreshRateX100 carries 11988.
+     *
+     * At native 4K, a fractional mode string (e.g. 3840x2160x119.88) produces a black video
+     * plane on some LG webOS sets (C5). Keep mode integer at 4K; clientRefreshRateX100 is
+     * still sent separately for encode pacing when NTSC is enabled. */
     const bool fractional = !is_gfe && client_refresh_x100 > 0 && (client_refresh_x100 % 100) != 0;
-    if (fractional) {
+    const bool uhd_4k = width >= 3840 && height >= 2160;
+    if (fractional && !uhd_4k) {
         append_param(url, url_len, "mode", "%dx%dx%d.%02d", width, height,
                      client_refresh_x100 / 100, client_refresh_x100 % 100);
     } else {

docs/superpowers/specs/2026-07-19-c5-4k-latency-and-v1.1.4-design.md

@@ -62,7 +62,7 @@ Limelight → session_video Feed
 5. **SS4S API** `SS4S_PlayerGetVideoRenderQueueLength(player, int *length)` → false if unsupported.
 6. **Overlay**: Starfish `RQ` was prototyped then dropped from the compact overlay (symbol unavailable on device → always `-`). Compact stats show a single FPS plus audio layout (Stereo / 5.1) instead.
 7. Keep Smooth PTS / host PTS mapping as in v1.1.3.
-8. **4K + NTSC:** launch `mode=` may carry fractional NTSC (e.g. `3840x2160x119.88`) when the option is enabled; `clientRefreshRateX100` is also sent for encode pacing.
+8. **4K + NTSC:** launch `mode=` stays integer at 4K (avoids black screen on C5); `clientRefreshRateX100` still carries NTSC for encode pacing.
 
 ## Phase B — Soft recovery (after C5 RQ validation)
 

src/app/app_settings.h

@@ -103,8 +103,6 @@ extern const size_t audio_config_len;
 #define RES_720P RES_MERGE(1280, 720)
 #define RES_1080P RES_MERGE(1920, 1080)
 #define RES_1440P RES_MERGE(2560, 1440)
-/** ~90% of 4K (3584×2016); stable on recent LG TVs without full-4K input delay */
-#define RES_3_6K RES_MERGE(3584, 2016)
 #define RES_1800P RES_MERGE(3200, 1800)
 #define RES_4K RES_MERGE(3840, 2160)
 

src/app/ui/settings/panes/basic.pane.c

@@ -152,9 +152,11 @@ static lv_obj_t *create_obj(lv_fragment_t *self, lv_obj_t *container) {
                                             &app_configuration->use_ntsc_refresh, false);
     lv_obj_add_event_cb(ntsc_checkbox, on_ntsc_refresh_changed, LV_EVENT_VALUE_CHANGED, self);
     pref_desc_label(view,
-                    locstr("When enabled, 60/120 FPS presets use fractional NTSC pacing (59.94/119.88), "
-                           "including at 4K. When disabled, presets use integer 60/120 like Moonlight mobile. "
-                           "Custom FPS still allows any fractional rate."),
+                    locstr("When enabled, 60/120 FPS presets use fractional NTSC pacing (59.94/119.88). "
+                           "When disabled, presets use integer 60/120 like Moonlight mobile. "
+                           "At 4K the host virtual-display mode stays integer (120) to avoid a black "
+                           "screen on some webOS TVs; NTSC is still sent as clientRefreshRateX100 for "
+                           "encode pacing. Custom FPS still allows any fractional rate."),
                     false);
 
     pref_desc_label(view,
@@ -264,8 +266,14 @@ static void update_bitrate_label(basic_pane_t *pane) {
 
 static void update_bitrate_hint(basic_pane_t *pane) {
     app_t *app = pane->parent->app;
-    if (app->ss4s.video_cap.suggestedBitrate > 0 &&
-        app_configuration->stream.bitrate > app->ss4s.video_cap.suggestedBitrate) {
+    const int bitrate = app_configuration->stream.bitrate;
+    if (bitrate > 250000) {
+        lv_obj_clear_flag(pane->bitrate_warning, LV_OBJ_FLAG_HIDDEN);
+        lv_label_set_text_static(pane->bitrate_warning,
+                                 locstr("Above 250 Mbps usually brings no quality gain and can cause "
+                                        "packet loss as the connection becomes less stable."));
+    } else if (app->ss4s.video_cap.suggestedBitrate > 0 &&
+               bitrate > app->ss4s.video_cap.suggestedBitrate) {
         lv_obj_clear_flag(pane->bitrate_warning, LV_OBJ_FLAG_HIDDEN);
         lv_label_set_text_static(pane->bitrate_warning, locstr("Higher bitrate may cause performance issue, "
                                                                "try with caution."));

src/app/ui/settings/panes/pref_res.c

@@ -39,7 +39,6 @@ static const resolution_pair_t built_in_resolutions[] = {
     {1280, 720, true, NULL},
     {1920, 1080, false, NULL},
     {2560, 1440, false, NULL},
-    {3584, 2016, false, "3.6K"},
     {3840, 2160, false, NULL},
 };
 

src/app/ui/settings/panes/video.pane.c

@@ -166,7 +166,7 @@ static lv_obj_t *create_obj(lv_fragment_t *self, lv_obj_t *container) {
     pref_desc_label(view,
                     locstr("Stamp video presentation timestamps on a steady frame grid instead of "
                            "wall-clock feed time. Reduces hitching when camera pans at high bitrate "
-                           "(e.g. 3.6K HDR HEVC). Disable only for A/B comparison."),
+                           "(e.g. 4K HDR HEVC). Disable only for A/B comparison."),
                     false);
     pref_checkbox(view, locstr("Pause at decode time (Starfish)"), &app_configuration->pause_at_decode_time, false);
     pref_desc_label(view,