Fix DVD audio compatibility gaps: bitrate, DTS, and track order

README.md

@@ -15,7 +15,7 @@ Current DVD authoring capabilities include:
 - menu editing with authored scene documents, layers, still-image composition nodes, and motion menus with intro/loop timing, audio beds, and timeout actions
 - animated button highlights authored as keyframe tracks on a timeline strip and compiled into the disc's subpicture stream
 - semantic interaction graphs and remote-navigation preview simulation
-- asset inspection with embedded metadata title surfacing, compatibility explanations, fix-oriented validation, and still-image imports for menu authoring
+- asset inspection with embedded metadata title surfacing, compatibility explanations (including per-codec DVD-Video audio bitrate ceilings, not just codec-name matching), fix-oriented validation, and still-image imports for menu authoring
 - DVD build planning and execution with diagnostics export and toolchain checks
 - bitmap subtitle muxing plus first-pass text subtitle rendering for DVD authoring
 

SPEC.md

@@ -543,8 +543,8 @@ The native toolchain adapter should detect which encoders and pass-through paths
 This matters especially for:
 
 - MP2 output availability
-- DTS output availability
-- copy and passthrough eligibility for existing compliant streams
+- DTS output availability — confirmed unavailable as a re-encode target regardless of environment: ffmpeg's only DTS encoder path produces a stream that decodes fine in isolation but corrupts once muxed through the DVD program-stream muxer, so re-encoding to DTS is refused outright at validation and build time. DTS remains available as a stream copy of an already-DTS source.
+- copy and passthrough eligibility for existing compliant streams — a source stream is only copy-eligible when both its codec name _and_ its bitrate are DVD-legal (e.g. AC-3 above 448 kbps is a valid AC-3 bitstream but exceeds the DVD-Video ceiling and still requires a re-encode despite the codec name matching)
 
 ### 12.2.5 Planner integration
 
@@ -1102,7 +1102,7 @@ The app should not hide the build pipeline, but it also should not dump raw tool
 
 - "Title 3 exceeds estimated disc budget by 412 MB after adding the second audio track."
 - "Subtitle track 2 is text-based and must be converted before DVD authoring."
-- "Requested DTS output is not available in the current toolchain configuration."
+- "Cannot re-encode audio track \"English\" to DTS — ffmpeg has no reliable DTS encoder (its native encoder produces DVD-incompatible output). DTS is only supported as a stream copy of an already-DTS source; re-encode to AC3 instead."
 - "Menu button 'Scenes' points to a missing chapter menu."
 
 ---
@@ -1514,7 +1514,7 @@ These should be resolved during design review.
 6. Should the project file remain pure JSON in v1, or should a sidecar cache database be introduced immediately? — This affects portability, transparency, migration complexity, and how derived data is separated from authored data.
 7. How should menu highlight/select assets be modelled internally to support both ease of use and DVD constraints? — This matters because button visuals are simple in the UI but have strict authored-disc implications.
 8. How much of the generated build pipeline should be user-overridable? — This determines how inspectable and hackable the tool should be for advanced users without making the normal workflow fragile.
-9. Should DTS output require a separate advanced-compatibility acknowledgement even when toolchain support is present? — This is about distinguishing legal authoring from broadly safe playback compatibility.
+9. ~~Should DTS output require a separate advanced-compatibility acknowledgement even when toolchain support is present?~~ Narrowed by the confirmed-broken ffmpeg DTS encoder (§12.2.4): DTS re-encoding isn't offered at all, toolchain-independent, so the open question is now only about copy-mode DTS passthrough, which is already unrestricted since it never touches the broken encoder.
 10. How aggressively should the app recommend Half-D1 over Full-D1 when bitrate pressure is high? — This affects how opinionated the planner becomes when trading resolution against expected quality.
 11. How should autogenerated menus be regenerated after the user has manually customised them? — This raises important questions about preserving edits, reapplying templates, and avoiding destructive regeneration.
 12. Should generated chapter, audio, and subtitle menus be opt-in per title or derived automatically from project rules? — This affects how much automation the app performs by default and how predictable the authored structure feels.

apps/spindle/src/pages/TitlesPage.tsx

@@ -547,11 +547,20 @@ function TitleEditor({
 		// Auto-map first video stream and create audio mappings
 		const videoMapping =
 			asset.videoStreams.length > 0
-				? { sourceStreamIndex: asset.videoStreams[0].index, copyMode: 'copy' as CopyMode }
+				? {
+						sourceStreamIndex: asset.videoStreams[0].index,
+						copyMode: (isVideoCopyCompatible(asset) ? 'copy' : 're-encode') as CopyMode,
+					}
 				: null;
 
+		// Both dimensions must hold for a legal stream copy: a DVD-legal
+		// codec name at an over-ceiling bitrate (e.g. 640 kbps AC-3) still
+		// needs a re-encode down to a DVD-legal rate.
 		const audioCompatByStream = new Map(
-			asset.compatibilityDetail?.audioStreams.map((c) => [c.streamIndex, c.codec.compatible]) ?? [],
+			asset.compatibilityDetail?.audioStreams.map((c) => [
+				c.streamIndex,
+				c.codec.compatible && c.bitrate.compatible,
+			]) ?? [],
 		);
 		const audioMappings = asset.audioStreams.map((as_, i) => {
 			const compatible = audioCompatByStream.get(as_.index) ?? false;
@@ -718,15 +727,23 @@ function TitleEditor({
 					<select
 						className="titles__select"
 						value={title.videoMapping?.sourceStreamIndex ?? ''}
-						onChange={(e) =>
+						onChange={(e) => {
+							const streamIndex = Number(e.target.value);
+							// Compatibility data only covers the inspected/primary
+							// stream (videoStreams[0]) — picking any other stream
+							// is data we have no compatibility signal for, so it
+							// must default to re-encode rather than assume copy.
+							const isPrimaryStream = streamIndex === selectedAsset.videoStreams[0]?.index;
 							onUpdate({
 								...title,
 								videoMapping: {
-									sourceStreamIndex: Number(e.target.value),
-									copyMode: 'copy',
+									sourceStreamIndex: streamIndex,
+									copyMode: (isPrimaryStream && isVideoCopyCompatible(selectedAsset)
+										? 'copy'
+										: 're-encode') as CopyMode,
 								},
-							})
-						}
+							});
+						}}
 					>
 						{selectedAsset.videoStreams.map((vs) => (
 							<option key={vs.index} value={vs.index}>
@@ -819,7 +836,13 @@ function TitleEditor({
 									<option value="AC3">AC3 (Dolby Digital)</option>
 									<option value="LPCM">LPCM</option>
 									<option value="MP2">MP2</option>
-									<option value="DTS">DTS</option>
+									<option
+										value="DTS"
+										disabled={am.copyMode !== 'copy'}
+										title="ffmpeg has no reliable DTS encoder — DTS is only supported as a passthrough of an already-DTS source, not as a re-encode target."
+									>
+										DTS{am.copyMode !== 'copy' ? ' (passthrough only)' : ''}
+									</option>
 								</select>
 								<select
 									className="titles__select"
@@ -838,6 +861,14 @@ function TitleEditor({
 													? {
 															...a,
 															copyMode,
+															// DTS re-encode isn't offered (no reliable ffmpeg
+															// encoder) — switching to Re-encode with DTS still
+															// selected must fall back rather than silently keep
+															// an option the UI no longer lets you pick.
+															outputTarget:
+																copyMode === 're-encode' && a.outputTarget === 'DTS'
+																	? 'AC3'
+																	: a.outputTarget,
 															// Channel layout and bitrate only apply to re-encoded
 															// tracks — clear them so a stale selection doesn't
 															// silently reappear if the user switches back later.
@@ -1238,7 +1269,21 @@ function isCopyCompatible(asset: Asset | null, mapping: AudioTrackMapping): bool
 	const compat = asset?.compatibilityDetail?.audioStreams.find(
 		(c) => c.streamIndex === mapping.sourceStreamIndex,
 	);
-	return compat?.codec.compatible ?? true;
+	if (!compat) return true;
+	// Both dimensions must hold: a DVD-legal codec at an over-ceiling
+	// bitrate (e.g. 640 kbps AC-3) still isn't legally copyable as-is.
+	return compat.codec.compatible && compat.bitrate.compatible;
+}
+
+// Unlike audio (a single per-stream codec check), video compatibility is
+// multi-dimensional and unindexed (`CompatibilityDetail.video` assesses
+// whichever stream inspection treated as primary — in practice always
+// videoStreams[0]) — codec, resolution, AND frame rate must all already be
+// DVD-legal for a stream copy to be valid; any one mismatch means re-encode.
+function isVideoCopyCompatible(asset: Asset | null): boolean {
+	const compat = asset?.compatibilityDetail?.video;
+	if (!compat) return true;
+	return compat.codec.compatible && compat.resolution.compatible && compat.frameRate.compatible;
 }
 
 function sourceChannelLabel(asset: Asset | null, mapping: AudioTrackMapping): string | null {

plugins/tauri-plugin-spindle-project/guest-js/index.ts

@@ -555,6 +555,7 @@ export interface VideoCompatibility {
 export interface AudioStreamCompatibility {
 	streamIndex: number;
 	codec: PropertyCheck;
+	bitrate: PropertyCheck;
 }
 
 export interface ContainerCompatibility {

plugins/tauri-plugin-spindle-project/src/build/authoring/language.rs

@@ -1,12 +1,12 @@
-// ISO 639 language code normalisation for dvdauthor subpicture stream
+// ISO 639 language code normalisation for dvdauthor audio/subpicture stream
 // declarations.
 //
 // (c) Copyright 2026 Liminal HQ, Scott Morris
 // SPDX-License-Identifier: MIT
 
 use isolang::Language;
 
-pub(super) fn dvdauthor_subpicture_language(language: &str) -> Option<String> {
+pub(super) fn dvdauthor_language_code(language: &str) -> Option<String> {
     let normalised = language
         .trim()
         .split(['-', '_'])

plugins/tauri-plugin-spindle-project/src/build/authoring/mod.rs

@@ -3,6 +3,7 @@
 // (c) Copyright 2026 Liminal HQ, Scott Morris
 // SPDX-License-Identifier: MIT
 
+use std::collections::HashMap;
 use std::path::Path;
 
 use crate::models::*;
@@ -29,6 +30,7 @@ pub(crate) fn generate_dvdauthor_xml(
         VideoStandard::Ntsc => "ntsc",
         VideoStandard::Pal => "pal",
     };
+    let assets: HashMap<&str, &Asset> = project.assets.iter().map(|a| (a.id.as_str(), a)).collect();
 
     let mut xml = String::new();
 
@@ -113,6 +115,7 @@ pub(crate) fn generate_dvdauthor_xml(
             titleset_index,
             &project.disc,
             titles_dir,
+            &assets,
         )?;
 
         xml.push_str("  </titleset>\n");

plugins/tauri-plugin-spindle-project/src/build/authoring/tests.rs

@@ -330,6 +330,80 @@ fn dvdauthor_xml_rejects_mixed_menu_aspects_within_one_section() {
         .contains("Menus in the same DVD menu section must share one display aspect"));
 }
 
+#[test]
+fn dvdauthor_xml_declares_audio_streams_in_authored_order() {
+    // Without explicit <audio> declarations, dvdauthor auto-detects audio
+    // streams from the vob itself, and its inferred physical-track order
+    // does not reliably match the order the streams actually appear in —
+    // observed in practice with a mixed AC3+MP2 title, where dvdauthor
+    // placed the second (MP2) stream at physical audio 0 regardless of
+    // which track was marked default. Declaring the order explicitly is
+    // the fix; this pins that the declared order matches audio_mappings.
+    let mut project = test_project();
+    project.disc.titlesets[0].titles[0]
+        .audio_mappings
+        .push(AudioTrackMapping {
+            id: "am-2".to_string(),
+            source_stream_index: 2,
+            output_target: AudioOutputTarget::Mp2,
+            copy_mode: CopyMode::ReEncode,
+            label: "Commentary".to_string(),
+            language: "eng".to_string(),
+            order_index: 1,
+            is_default: false,
+            channel_layout: None,
+            bitrate_bps: None,
+        });
+
+    let plan = generate_build_plan(&project, "/tmp/dvd_output", false).unwrap();
+
+    let ac3_pos = plan
+        .dvdauthor_xml
+        .find("<audio format=\"ac3\" lang=\"en\" />")
+        .expect("expected an ac3 audio declaration");
+    let mp2_pos = plan
+        .dvdauthor_xml
+        .find("<audio format=\"mp2\" lang=\"en\" />")
+        .expect("expected an mp2 audio declaration");
+    assert!(
+        ac3_pos < mp2_pos,
+        "expected the default (ac3) audio track declared before the \
+         non-default (mp2) track\n{}",
+        plan.dvdauthor_xml
+    );
+}
+
+#[test]
+fn dvdauthor_xml_declares_copied_audio_using_the_actual_source_codec() {
+    // A CopyMode::Copy mapping passes the source stream's own bytes through
+    // unchanged (build_ffmpeg_transcode_command emits `-c:a copy`, ignoring
+    // output_target entirely) — but the UI lets output_target and copyMode
+    // be set independently, so a track can end up in copy mode with a
+    // stale output_target left over from before the user switched modes
+    // (e.g. was re-encoding AC3 -> MP2, then switched to copy). Declaring
+    // that stale output_target's format to dvdauthor would tell it a
+    // physical AC3 stream is MP2, which can make dvdauthor reject or
+    // mis-author the stream. The declared format must come from the
+    // source's real codec for copied mappings.
+    let mut project = test_project();
+    project.assets[0].audio_streams[0].codec = "ac3".to_string();
+    project.disc.titlesets[0].titles[0].audio_mappings[0].copy_mode = CopyMode::Copy;
+    project.disc.titlesets[0].titles[0].audio_mappings[0].output_target = AudioOutputTarget::Mp2;
+
+    let plan = generate_build_plan(&project, "/tmp/dvd_output", false).unwrap();
+
+    assert!(
+        plan.dvdauthor_xml.contains("<audio format=\"ac3\" lang=\"en\" />"),
+        "expected the copied stream declared using its real ac3 source codec, not the stale mp2 output_target\n{}",
+        plan.dvdauthor_xml
+    );
+    assert!(
+        !plan.dvdauthor_xml.contains("<audio format=\"mp2\""),
+        "must not declare the stale mp2 output_target for a copy-mode mapping\n{}",
+        plan.dvdauthor_xml
+    );
+}
+
 #[test]
 fn dvdauthor_xml_normalises_subpicture_languages_for_dvdauthor() {
     let mut project = test_project();