fix: enhance 2-pass x265 encoding to copy compatible HEVC video below specified bitrate limit

LocalFlowPlugins/video/transcode2PassX265/1.0.0/index.js

@@ -7,7 +7,8 @@ const fs   = require('fs');
 
 /**
  * transcode2PassX265
- * Performs 2-pass x265 encoding with:
+ * Performs 2-pass x265 encoding, unless the input is already a compatible
+ * low-bitrate HEVC stream, with:
  *   - Bound-1080p Lanczos scaling (no letterbox, even dimensions)
  *   - VBV rate control from args.variables
  *   - Dynamic Opus audio mapping (ITA default, ENG secondary)
@@ -19,8 +20,9 @@ const fs   = require('fs');
 const details = () => ({
   name: '2-Pass x265 Transcode',
   description:
-    'Performs 2-pass libx265 encoding using parameters from args.variables. '
+    'Performs 2-pass libx265 encoding using parameters from args.variables, '
-    + 'Applies bound-1080p Lanczos scaling, Opus audio re-encoding, '
+    + 'or copies compatible HEVC video below the configured bitrate limit. '
+    + 'Applies bound-1080p Lanczos scaling when encoding, Opus audio re-encoding, '
     + 'and chapter preservation. Cross-platform (Linux server / Windows worker).',
   style: { borderColor: '#E91E63' },
   tags: 'video,ffmpeg,x265',
@@ -49,6 +51,16 @@ const details = () => ({
       inputUI: { type: 'text' },
       tooltip: 'Output file container extension (mkv recommended).',
     },
+    {
+      label: 'Copy HEVC Below (kbps)',
+      name: 'copyHevcBelowKbps',
+      type: 'string',
+      defaultValue: '3000',
+      inputUI: { type: 'text' },
+      tooltip:
+        'Copy video instead of re-encoding when it is HEVC, is already 1080p or smaller, '
+        + 'and its reported bitrate is strictly below this value. Set 0 to disable copying.',
+    },
   ],
   outputs: [
     { number: 1, tooltip: 'Transcode complete — output file ready' },
@@ -95,6 +107,19 @@ const buildAudioArgs = (variables) => {
   return [...mapArgs, ...codecArgs];
 };
 
+const shouldCopyVideo = (videoStream, copyHevcBelowKbps) => {
+  if (!videoStream || String(videoStream.codec_name || '').toLowerCase() !== 'hevc') return false;
+
+  const width = parseInt(videoStream.width, 10) || 0;
+  const height = parseInt(videoStream.height, 10) || 0;
+  const bitrateKbps = (parseInt(videoStream.bit_rate, 10) || 0) / 1000;
+
+  return copyHevcBelowKbps > 0
+    && width > 0 && width <= 1920
+    && height > 0 && height <= 1080
+    && bitrateKbps > 0 && bitrateKbps < copyHevcBelowKbps;
+};
+
 // ─── Plugin ───────────────────────────────────────────────────────────────────
 
 const plugin = async (args) => {
@@ -115,6 +140,11 @@ const plugin = async (args) => {
 
   const x265Preset   = args.inputs.x265Preset    || 'slow';
   const container    = args.inputs.outputContainer || 'mkv';
+  const copyHevcBelowKbps = Math.max(0, parseInt(args.inputs.copyHevcBelowKbps || '3000', 10) || 0);
+  const streams = (inputFileObj.ffProbeData && inputFileObj.ffProbeData.streams) || [];
+  const videoStream = streams.find((stream) => stream.codec_type === 'video');
+  if (!videoStream) throw new Error('[transcode2PassX265] No video stream found.');
+  const copyVideo = shouldCopyVideo(videoStream, copyHevcBelowKbps);
 
   // Parse numeric VBV values (parseInt handles trailing 'k')
   const maxRateNum = parseInt(vMaxRate, 10);
@@ -124,6 +154,12 @@ const plugin = async (args) => {
     `[transcode2PassX265] Params: bitrate=${vBitrate} maxrate=${maxRateNum}k `
     + `bufsize=${bufSizeNum}k keyint=${gopKeyint} tune=${x265Tune || 'none'} preset=${x265Preset}\n`,
   );
+  const sourceBitrateKbps = ((parseInt(videoStream.bit_rate, 10) || 0) / 1000).toFixed(0);
+  jobLog(
+    `[transcode2PassX265] Video: codec=${videoStream.codec_name || 'unknown'} `
+    + `${videoStream.width || '?'}x${videoStream.height || '?'} bitrate=${sourceBitrateKbps}k `
+    + `mode=${copyVideo ? 'copy' : '2-pass-x265'} (copy limit <${copyHevcBelowKbps}k)\n`,
+  );
 
   // ── Paths ─────────────────────────────────────────────────────────────────
   const baseName    = path.basename(inputFile, path.extname(inputFile));
@@ -135,7 +171,7 @@ const plugin = async (args) => {
 
   jobLog(`[transcode2PassX265] Output: ${outFile}\n`);
 
-  // ── Video filter ──────────────────────────────────────────────────────────
+  // ── Video filter / args ───────────────────────────────────────────────────
   const vf = [
     "scale='min(1920,iw)':'min(1080,ih)':force_original_aspect_ratio=decrease",
     'scale=trunc(iw/2)*2:trunc(ih/2)*2:flags=lanczos',
@@ -154,7 +190,7 @@ const plugin = async (args) => {
 
   // ── Common video args ─────────────────────────────────────────────────────
   const tuneArgs = x265Tune ? ['-tune', x265Tune] : [];
-  const videoArgs = [
+  const encodeVideoArgs = [
     '-vf', vf,
     '-c:v', 'libx265',
     '-b:v', vBitrate,
@@ -162,6 +198,52 @@ const plugin = async (args) => {
     ...tuneArgs,
   ];
 
+  const videoArgs = copyVideo ? ['-c:v', 'copy'] : encodeVideoArgs;
+
+  // A stream copy has no encoder pass.  The normal pass-2 command below still
+  // remuxes the copied video while re-encoding the selected audio tracks.
+  if (copyVideo) {
+    const audioArgs = buildAudioArgs(variables);
+    if (audioArgs.length === 0) {
+      jobLog('[transcode2PassX265] WARNING: No audio streams mapped (no ITA/ENG found).\n');
+    }
+
+    jobLog('[transcode2PassX265] Copying compatible video and processing audio...\n');
+    const { CLI } = require('../../../../FlowHelpers/1.0.0/cliUtils');
+    const copyCli = new CLI({
+      cli: args.ffmpegPath,
+      spawnArgs: [
+        '-y',
+        '-i', inputFile,
+        '-map', '0:v:0',
+        ...audioArgs,
+        '-map_metadata', '-1',
+        '-map_chapters', '-1',
+        '-disposition:v:0', 'default',
+        ...videoArgs,
+        '-sn',
+        outFile,
+      ],
+      WorkDir: workDir,
+      jobLog,
+      inputFileObj,
+      updateWorker,
+      args,
+    });
+
+    const { cliExitCode } = await copyCli.runCli();
+    if (cliExitCode !== 0) {
+      throw new Error(`[transcode2PassX265] Video-copy/audio-transcode failed with exit code ${cliExitCode}`);
+    }
+
+    jobLog(`[transcode2PassX265] Done. Output: ${outFile}\n`);
+    return {
+      outputNumber: 1,
+      outputFileObj: { ...inputFileObj, _id: outFile },
+      variables,
+    };
+  }
+
   const { CLI } = require('../../../../FlowHelpers/1.0.0/cliUtils');
 
   // ══ PASS 1 ════════════════════════════════════════════════════════════════

README.md

@@ -223,7 +223,7 @@ OCR failures are logged as **warnings** without stopping the pipeline.
 
 Performs 2-pass libx265 encoding using VBV parameters from `args.variables`.
 
-- **Video**: bound-1080p Lanczos scaling (no letterbox, even dimensions)
+- **Video**: HEVC already within 1080p and strictly below 3000 kbps is copied; all other video is bound-1080p Lanczos scaled and x265-encoded (no letterbox, even dimensions)
 - **Audio**: Opus re-encode with per-track indexed bitrate (ITA default, ENG secondary)
 - **Subtitles**: stripped (`-sn`)
 - **Chapters**: preserved (`-map_chapters 0`)
@@ -233,6 +233,7 @@ Performs 2-pass libx265 encoding using VBV parameters from `args.variables`.
 |---|---|---|
 | `x265Preset` | `slow` | x265 preset (`ultrafast` … `veryslow`). Slower = better quality. |
 | `outputContainer` | `mkv` | Output file extension |
+| `copyHevcBelowKbps` | `3000` | Copy compatible HEVC video below this bitrate instead of re-encoding it. `0` disables copying. |
 
 **Outputs**: `1` → transcode complete
 

tests/quick-logic-test.js

@@ -197,6 +197,9 @@ const AUDIO_INPUTS = {
   ok(transcodeCode.includes('`-b:a:${audioTrackOut}`'), 'buildAudioArgs uses indexed -b:a:N (not global -b:a)');
   ok(transcodeCode.includes('[...mapArgs, ...codecArgs]'), 'buildAudioArgs: maps first, then codec settings');
   ok(!transcodeCode.includes("'-c:a', 'libopus'"), 'no unindexed -c:a in buildAudioArgs');
+  ok(transcodeCode.includes('bitrateKbps < copyHevcBelowKbps'), 'HEVC copy requires bitrate strictly below the limit');
+  ok(transcodeCode.includes("copyHevcBelowKbps || '3000'"), 'HEVC copy limit defaults to 3000 kbps');
+  ok(transcodeCode.includes("'-c:v', 'copy'"), 'compatible HEVC video uses stream copy');
 
   // ── Summary ───────────────────────────────────────────────────────────────
   console.log(`\n${'='.repeat(55)}`);