From 3ee4144a8123da467cc771acc1d449e98668a8e2 Mon Sep 17 00:00:00 2001
From: Jason Lu <151680919+Nottlespike@users.noreply.github.com>
Date: Wed, 27 May 2026 08:31:58 -0700
Subject: [PATCH] fix(macos): drop max_ref_frames=1 for h264_videotoolbox and
 enable PARALLEL_ENCODING (#5200)

---
 src/video.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/video.cpp b/src/video.cpp
index 00af66c3a..f2281ce84 100644
--- a/src/video.cpp
+++ b/src/video.cpp
@@ -1134,12 +1134,16 @@ namespace video {
     },
     {
       // Common options
+      // Note: max_ref_frames is intentionally omitted for H.264 because
+      // VideoToolbox on Apple Silicon produces all-IDR output when
+      // ReferenceBufferCount=1 is set for H.264, causing massive bandwidth
+      // inflation (~3x) and frame drops. HEVC and AV1 are unaffected and
+      // retain max_ref_frames=1. See LizardByte/Sunshine#5013.
       {
         {"allow_sw"s, &config::video.vt.vt_allow_sw},
         {"require_sw"s, &config::video.vt.vt_require_sw},
         {"realtime"s, &config::video.vt.vt_realtime},
         {"prio_speed"s, 1},
-        {"max_ref_frames"s, 1},
       },
       {},  // SDR-specific options
       {},  // HDR-specific options
@@ -1151,7 +1155,7 @@ namespace video {
       },
       "h264_videotoolbox"s,
     },
-    DEFAULT
+    PARALLEL_ENCODING
   };
 #endif