feat(conform): audio cross-fades authored — harvested template, ramp-verified

- Harvested a real audio Sm2TiTransition by importing an FCP7
  KGAudioTransCrossFade via XMEML (Resolve stores PrettyType 'Final Cut
  Pro 7' for it — and renders it); bundled as
  templates/transition-cross-fade-r19.xml (Element-wrapped, guard test
  extended).
- placeTransition: trackType 'audio' places the harvested cross-fade
  (unknown trackType still refuses); assemble passes transitions[].trackType.
- eventsToAssembleSpec: audio events with dissolves author audio cross-fades
  under the same abut/handle geometry; drops carry trackType:'audio' + reason.
- Render proof (19.1.3.7): the offline-authored crossfade's highpass-RMS
  RAMPS through the junction (-27.6 → -25.6 → -23.0 → -21.9), identical
  shape to a Resolve-authored control; a butt cut steps.
- XMEML import gotcha recorded: an <audio><channelcount> block inside a FILE
  definition aborts the entire import silently ('created no timeline').
- 2 new bridge tests; wrapper guard covers the new template; guide table row.

Suites after last edit (incl. version bump): Node 828 pass / 0 fail;
Python 3101 passed + 799 subtests.

Author: samuelgursky

docs/guides/native-drt-authoring.md

@@ -42,6 +42,7 @@ window. `render.verify_output` covers the container-level checks.
 | Media cuts, multi-source | `media: [{mediaFilePath, spec, cuts}]` | v2.106–2.107 |
 | Multi-track video (V2+ stacking) | `cuts[].track` (video-only above V1) | v2.112 |
 | Cross-dissolves | `transitions: [{track, atFrame, durationFrames}]` | v2.111 |
+| Audio cross-fades | `transitions[].trackType: 'audio'` | v2.116 |
 | Constant retimes, forward | `cuts[].speed` (e.g. `0.5`) | v2.113 |
 | Constant retimes, reverse | `cuts[].reverse` | v2.114 |
 | Audio placements, A1–A8 | `cuts[].audioOnly + track` | v2.115 |

install.py

@@ -37,7 +37,7 @@
 
 # ─── Version ──────────────────────────────────────────────────────────────────
 
-VERSION = "2.115.1"
+VERSION = "2.116.0"
 # Only hard floor: mcp[cli] requires Python 3.10+. There is no upper bound —
 # Resolve's scripting bridge loads into newer interpreters on recent builds
 # (Python 3.14 verified against Resolve Studio 20.3.2). Older Resolve builds

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "davinci-resolve-mcp",
-  "version": "2.115.1",
+  "version": "2.116.0",
   "description": "NPM bootstrapper for the DaVinci Resolve MCP Server.",
   "license": "MIT",
   "author": "Samuel Gursky <samgursky@gmail.com>",

package.json

@@ -299,6 +299,7 @@ export function eventsToAssembleSpec(events, opts = {}) {
   const audioTrackNum = (t) => { const m = /^A(\d+)?$/.exec(String(t)); return m && m[1] ? parseInt(m[1], 10) : 1; };
   const audioPlacements = [];
   const audioRetimesSkipped = [];
+  const audioTransCandidates = [];
   for (const e of auds) {
     const recIn = ORIGIN + (toTl(e.recIn, e.fps) - minRec);
     const recOut = ORIGIN + (toTl(e.recOut, e.fps) - minRec);
@@ -309,7 +310,16 @@ export function eventsToAssembleSpec(events, opts = {}) {
     }
     const track = audioTrackNum(e.track);
     const cut = { startFrame: recIn, durationFrames, srcIn: toTl(e.srcIn ?? 0, e.fps), audioOnly: true, track };
-    audioPlacements.push({ start: recIn, end: recOut, index: e.index, track });
+    if (e.transition) {
+      let d = Math.max(2, toTl(e.transition.duration || 0, e.fps) || 2);
+      d += d % 2;
+      audioTransCandidates.push({
+        atFrame: recIn, durationFrames: d, track,
+        index: e.index, type: e.transition.type, rawDuration: e.transition.duration,
+        source: e.source, srcIn: cut.srcIn,
+      });
+    }
+    audioPlacements.push({ start: recIn, end: recOut, index: e.index, track, source: e.source, srcIn: cut.srcIn, durationFrames });
     if (!perSource.has(e.source)) perSource.set(e.source, []);
     perSource.get(e.source).push(cut);
   }
@@ -384,6 +394,29 @@ export function eventsToAssembleSpec(events, opts = {}) {
     }
     transitions.push({ track: c.track, atFrame: c.atFrame, durationFrames: c.durationFrames });
   }
+  // Audio cross-fades, same geometry rules (render-verified on 19.1.3.7 via
+  // the harvested cross-fade template: the highpass RMS ramps, not steps).
+  for (const c of audioTransCandidates) {
+    const prev = audioPlacements.find((pl) => pl.track === c.track && pl.end === c.atFrame);
+    if (!prev) {
+      droppedTransitions.push({ index: c.index, type: c.type, duration: c.rawDuration, trackType: 'audio', reason: 'no abutting predecessor at the cut' });
+      continue;
+    }
+    const half = c.durationFrames / 2;
+    const bHandle = c.srcIn >= half;
+    const aSpec = sourceMap[prev.source] && sourceMap[prev.source].spec;
+    const aFrames = aSpec && Number(aSpec.frameCount);
+    const aHandle = Number.isFinite(aFrames) ? prev.srcIn + prev.durationFrames + half <= aFrames : false;
+    if (!bHandle || !aHandle) {
+      droppedTransitions.push({
+        index: c.index, type: c.type, duration: c.rawDuration, trackType: 'audio',
+        reason: `insufficient handles for a centered ${c.durationFrames}f cross-fade` +
+          `${bHandle ? '' : ' (incoming srcIn < half)'}${aHandle ? '' : ' (outgoing tail media < half)'}`,
+      });
+      continue;
+    }
+    transitions.push({ track: c.track, atFrame: c.atFrame, durationFrames: c.durationFrames, trackType: 'audio' });
+  }
 
   return {
     spec: { timelineName, media, ...(transitions.length ? { transitions } : {}) },

resolve-advanced/server/author-interchange.mjs

@@ -46,7 +46,7 @@ const assembleSchema = z.object({
   spec: z
     .object({})
     .passthrough()
-    .describe("assembleTimeline spec: { timelineName?, media?: {mediaFilePath, spec:{width,height,frameCount,fps}, cuts:[{startFrame,durationFrames,srcIn?,track? (1-based video track; >1 = video-only, render-verified stacking),speed?/reverse? (constant retime, e.g. 0.5, forward or backwards; video-only; readback+render-verified on 19),audioOnly?+track? (explicit AUDIO placement on audio track 1-8; presence suppresses the A1 mirror; render-verified on 19)}]} | [same, ...] (multi-source needs media_pool.capture_media_template run once per file), elements?: [{type:'title'|'generator', track, startFrame, durationFrames?, text?, generatorName? ('Solid Color'|'SMPTE Color Bar'|'Grey Scale' render-verified on 19), ...}], transitions? }. startFrame is timeline-absolute (origin 86400)."),
+    .describe("assembleTimeline spec: { timelineName?, media?: {mediaFilePath, spec:{width,height,frameCount,fps}, cuts:[{startFrame,durationFrames,srcIn?,track? (1-based video track; >1 = video-only, render-verified stacking),speed?/reverse? (constant retime, e.g. 0.5, forward or backwards; video-only; readback+render-verified on 19),audioOnly?+track? (explicit AUDIO placement on audio track 1-8; presence suppresses the A1 mirror; render-verified on 19)}]} | [same, ...] (multi-source needs media_pool.capture_media_template run once per file), transitions?: [{track, atFrame, durationFrames?, trackType? ('video' dissolve | 'audio' cross-fade, both render-verified on 19)}], elements?: [{type:'title'|'generator', track, startFrame, durationFrames?, text?, generatorName? ('Solid Color'|'SMPTE Color Bar'|'Grey Scale' render-verified on 19), ...}] }. startFrame is timeline-absolute (origin 86400)."),
   outputPath: z.string().describe('Absolute path where the importable .drt will be written'),
   targetAppVersion: z
     .union([z.string(), z.number()])

resolve-advanced/server/tools/drt.mjs

@@ -308,3 +308,36 @@ test('audio cuts beyond the template ceiling refuse at assemble time', async ()
     /audio track 9 exceeds the template's 8 audio tracks/,
   );
 });
+
+// Audio cross-fades: same geometry rules as video dissolves; the harvested
+// cross-fade template renders a RAMP through the junction (verified on
+// 19.1.3.7 against a Resolve-authored control: -27.6 → -25.6 → -23.0 → -21.9
+// highpass-RMS, identical shape).
+test('an EDL audio dissolve with handles authors an audio cross-fade', () => {
+  const edl = [
+    'TITLE: AX',
+    'FCM: NON-DROP FRAME',
+    '001  TAPE1 A     C        00:00:01:00 00:00:03:00 01:00:00:00 01:00:02:00',
+    '002  TAPE2 A     D    024 00:00:01:00 00:00:03:00 01:00:02:00 01:00:04:00',
+    '003  TAPE1 V     C        00:00:01:00 00:00:05:00 01:00:00:00 01:00:04:00',
+    '',
+  ].join('\n');
+  const { spec, report } = eventsToAssembleSpec(parseEDL(edl, { fps: 24 }), { sourceMap: MAP });
+  assert.deepEqual(report.authoredTransitions, [{ track: 1, atFrame: 86448, durationFrames: 24, trackType: 'audio' }]);
+  assert.equal(report.droppedTransitions.length, 0);
+  assert.deepEqual(spec.transitions, report.authoredTransitions);
+});
+
+test('an audio dissolve without an abutting predecessor drops with trackType audio', () => {
+  const edl = [
+    'TITLE: AX',
+    'FCM: NON-DROP FRAME',
+    '001  TAPE1 V     C        00:00:01:00 00:00:05:00 01:00:00:00 01:00:04:00',
+    '002  TAPE2 A     D    024 00:00:01:00 00:00:03:00 01:00:02:00 01:00:04:00',
+    '',
+  ].join('\n');
+  const { report } = eventsToAssembleSpec(parseEDL(edl, { fps: 24 }), { sourceMap: MAP });
+  assert.equal(report.droppedTransitions.length, 1);
+  assert.equal(report.droppedTransitions[0].trackType, 'audio');
+  assert.match(report.droppedTransitions[0].reason, /no abutting predecessor/);
+});

resolve-advanced/test/events-to-assemble.test.mjs

@@ -124,7 +124,7 @@ test('harvested r19 snippets are Element-wrapped (unwrapped clips break the trac
   // outright with no status (measured); the wrapper is load-bearing.
   const fs3 = require('node:fs');
   const path3 = require('node:path');
-  for (const f of ['fusion-title-r19.xml', 'generator-solid-color-r19.xml', 'fusion-title.xml', 'generator-solid-color.xml']) {
+  for (const f of ['fusion-title-r19.xml', 'generator-solid-color-r19.xml', 'fusion-title.xml', 'generator-solid-color.xml', 'transition-cross-fade-r19.xml']) {
     const s = fs3.readFileSync(
       path3.join(process.cwd(), 'vendor', 'drp-format', 'templates', f), 'utf8').trim();
     assert.ok(s.startsWith('<Element>'), `${f} must start with <Element>`);

resolve-advanced/test/media-template-transplant.test.mjs

@@ -44,5 +44,7 @@ test('placeTransition errors when no abutting boundary at atFrame', async () =>
 test('placeTransition validates args', async () => {
   const buf = await synth2();
   await assert.rejects(() => placeTransition(buf, { track: 1, atFrame: 100, durationFrames: 1 }), /durationFrames/);
-  await assert.rejects(() => placeTransition(buf, { track: 1, atFrame: 100, trackType: 'audio' }), /only video/);
+  // trackType 'audio' is now supported (harvested cross-fade template,
+  // v2.116.0); an unknown trackType still refuses.
+  await assert.rejects(() => placeTransition(buf, { track: 1, atFrame: 100, trackType: 'subtitle' }), /video or audio/);
 });

resolve-advanced/vendor/drp-format/__tests__/place-transition.test.js

@@ -181,6 +181,7 @@ async function assembleTimeline(spec = {}) {
     if (!tr || typeof tr !== 'object') throw new TypeError(`assembleTimeline: transitions[${i}] must be an object`);
     ({ buffer } = await placeTransition(buffer, {
       track: tr.track, atFrame: tr.atFrame, durationFrames: tr.durationFrames,
+      trackType: tr.trackType || 'video',
     }));
   }