From a8ee9552a07afa8fa5b1d1a0d26725a46a32863d Mon Sep 17 00:00:00 2001
From: mofeng-git <mofeng654321@hotmail.com>
Date: Sat, 5 Sep 2026 14:10:53 +0800
Subject: [PATCH] =?UTF-8?q?perf(video):=20=E4=BD=BF=E7=94=A8=E6=9C=89?=
 =?UTF-8?q?=E7=95=8C=20VBR=20=E4=BC=98=E5=8C=96=20H264=20=E7=A0=81?=
 =?UTF-8?q?=E7=8E=87?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

H264 编码器探测与初始化使用 VBR，将峰值码率和缓冲区限制为目标码率的两倍。动态调整码率时同步更新限制，并保留 QSV 的专用处理。
---
 libs/hwcodec/cpp/common/util.cpp | 12 ++++++++++++
 src/video/codec/h264.rs          |  4 ++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/libs/hwcodec/cpp/common/util.cpp b/libs/hwcodec/cpp/common/util.cpp
index 0894f4eb..a2762aab 100644
--- a/libs/hwcodec/cpp/common/util.cpp
+++ b/libs/hwcodec/cpp/common/util.cpp
@@ -397,6 +397,14 @@ struct CodecOptions {
 
 bool set_rate_control(AVCodecContext *c, const std::string &name, int rc,
                       int q) {
+  // Remote-desktop content is usually sparse. VBR avoids padding static
+  // frames up to the target bitrate while allowing short bursts for screen
+  // changes. Keep those bursts bounded at twice the target bitrate.
+  if (rc == RC_VBR && c->bit_rate > 0) {
+    c->rc_max_rate = c->bit_rate * 2;
+    c->rc_buffer_size = c->rc_max_rate;
+  }
+
   if (name.find("vaapi") != std::string::npos && rc == RC_CQ) {
     // Used only after the normal bitrate-based VAAPI initialization fails.
     // Some drivers, including Intel iHD on Jasper Lake, expose CQP as their
@@ -495,6 +503,10 @@ bool set_others(void *priv_data, const std::string &name) {
 bool change_bit_rate(AVCodecContext *c, const std::string &name, int kbs) {
   if (kbs > 0) {
     c->bit_rate = kbs * 1000;
+    if (c->rc_max_rate > 0 && name.find("qsv") == std::string::npos) {
+      c->rc_max_rate = c->bit_rate * 2;
+      c->rc_buffer_size = c->rc_max_rate;
+    }
     if (name.find("qsv") != std::string::npos) {
       c->rc_max_rate = c->bit_rate;
     }
diff --git a/src/video/codec/h264.rs b/src/video/codec/h264.rs
index 13d7a3a8..8b0ac59a 100644
--- a/src/video/codec/h264.rs
+++ b/src/video/codec/h264.rs
@@ -198,7 +198,7 @@ pub fn get_available_encoders(width: u32, height: u32) -> Vec<CodecInfo> {
         align: 1,
         fps: 30,
         gop: 30,
-        rc: RateControl::RC_CBR,
+        rc: RateControl::RC_VBR,
         quality: Quality::Quality_Low, // Use low quality preset for fastest encoding (ultrafast)
         kbs: 2000,
         q: 23,
@@ -297,7 +297,7 @@ impl H264Encoder {
             align: 1,
             fps: config.fps as i32,
             gop: config.gop_size as i32,
-            rc: RateControl::RC_CBR,
+            rc: RateControl::RC_VBR,
             quality: Quality::Quality_Low, // Use low quality preset for fastest encoding (lowest latency)
             kbs: config.bitrate_kbps as i32,
             q: 23,