fix: update GOP parameters for mediaAnalyzerGOP and transcode2PassX265 to enhance encoding efficiency and documentation

LocalFlowPlugins/utility/mediaAnalyzerGOP/1.0.0/index.js

@@ -6,7 +6,9 @@
  * mediaAnalyzerGOP
  * Analyzes the video stream and populates args.variables with encoding
  * parameters consumed by downstream plugins:
- *   gopKeyint / gopMinKeyint  -> 2 x FPS (rounded)
+ *   gopKeyint                 -> 4 x FPS (rounded; maximum 4-second GOP)
+ *   gopMinKeyint              -> 1 x FPS (rounded; permits scene cuts)
+ *   gopSceneCut               -> x265 scene-cut threshold (40)
  *   isAnimation               -> detected from animeSeries path list
  *   isMovie                   -> detected from moviePathPatterns
  *   vBitrate / vMaxRate / vBufSize
@@ -17,7 +19,7 @@
 const details = () => ({
   name: 'Media Analyzer & GOP Calculator',
   description:
-    'Analyzes video metadata, calculates GOP keyint (2xFPS), target bitrate '
+    'Analyzes video metadata, calculates a streaming-friendly 4-second GOP, target bitrate '
     + 'and VBV parameters based on content type (film/series/anime). '
     + 'Exports all values to args.variables for downstream plugins.',
   style: { borderColor: '#2196F3' },
@@ -123,8 +125,13 @@ const plugin = async (args) => {
   }
   jobLog(`[mediaAnalyzerGOP] FPS: ${fps.toFixed(3)}\n`);
 
-  const gopKeyint = String(Math.round(fps * 2));
-  jobLog(`[mediaAnalyzerGOP] keyint=${gopKeyint}\n`);
+  // A four-second maximum GOP is a compromise for remote streaming: it
+  // reduces regular I-frame overhead while keeping seek recovery short.
+  // A one-second minimum leaves x265 free to insert an I-frame at a real cut.
+  const gopKeyint = String(Math.round(fps * 4));
+  const gopMinKeyint = String(Math.round(fps));
+  const gopSceneCut = '40';
+  jobLog(`[mediaAnalyzerGOP] keyint=${gopKeyint} min-keyint=${gopMinKeyint} scenecut=${gopSceneCut}\n`);
 
   // Normalize to forward slashes for cross-platform path matching
   const normalizedPath = filePath.replace(/\\/g, '/');
@@ -149,7 +156,8 @@ const plugin = async (args) => {
   jobLog(`[mediaAnalyzerGOP] vBitrate=${vBitrate} vMaxRate=${vMaxRate} vBufSize=${vBufSize}\n`);
 
   variables.gopKeyint    = gopKeyint;
-  variables.gopMinKeyint = gopKeyint;
+  variables.gopMinKeyint = gopMinKeyint;
+  variables.gopSceneCut  = gopSceneCut;
   variables.isAnimation  = String(isAnimation);
   variables.isMovie      = String(isMovie);
   variables.vBitrate     = vBitrate;

LocalFlowPlugins/video/transcode2PassX265/1.0.0/index.js

@@ -166,8 +166,9 @@ const plugin = async (args) => {
 
   // ── Read variables ────────────────────────────────────────────────────────
   const {
-    gopKeyint    = '48',
-    gopMinKeyint = '48',
+    gopKeyint    = '96',
+    gopMinKeyint = '24',
+    gopSceneCut  = '40',
     vBitrate     = '3000k',
     vMaxRate     = '6000k',
     vBufSize     = '12000k',
@@ -189,7 +190,8 @@ const plugin = async (args) => {
 
   jobLog(
     `[transcode2PassX265] Params: bitrate=${vBitrate} maxrate=${maxRateNum}k `
-    + `bufsize=${bufSizeNum}k keyint=${gopKeyint} tune=${x265Tune || 'none'} preset=${x265Preset}\n`,
+    + `bufsize=${bufSizeNum}k keyint=${gopKeyint} min-keyint=${gopMinKeyint} scenecut=${gopSceneCut} `
+    + `tune=${x265Tune || 'none'} preset=${x265Preset}\n`,
   );
   const sourceBitrateKbps = getVideoBitrateKbps(videoStream, streams, format).toFixed(0);
   jobLog(
@@ -219,7 +221,7 @@ const plugin = async (args) => {
   const x265ParamsBase = [
     `keyint=${gopKeyint}`,
     `min-keyint=${gopMinKeyint}`,
-    `scenecut=0`,
+    `scenecut=${gopSceneCut}`,
     `open-gop=0`,
     `vbv-maxrate=${maxRateNum}`,
     `vbv-bufsize=${bufSizeNum}`,