labels: add dbp parser (Magnolia Pictures BD-J framework)

5th BD-J authoring framework recognized. Discriminator: any top-
level .jar in /BDMV/JAR/ that contains com/dbp/ package paths.
Identified during the 2026-05-10 corpus session via string-mining
disc-07's BD-J jar — perm files reference bd-live.magpictures.com
(Magnolia / Magnet Releasing).

Stream labels live as plain ASCII strings inside compiled .class
files in the form

    LTextField,Audio1,English Dolby Atmos,Fontstrip_Composite,...
    HTextField,Subtitle1,English SDH,Fontstrip_Composite,...
    ATextField,Subtitle0,None,Fontstrip_Composite,...

— a quirk of the menu-rendering layer encoding TextField positions
and content as constant strings the Java compiler retained in the
class string pool. The leading single-letter prefix is string-pool
ordering noise; parser anchors on `TextField,`. Subtitle0 is the
disable-subtitles button and is skipped.

The parser:
  - reads each top-level .jar via udf.read_file
  - opens it with the existing zip dependency
  - confirms com/dbp/ presence in the central directory
  - walks .class entries, extracts printable strings, matches the
    `TextField,(Audio|Subtitle)<N>,<label>,...` pattern
  - maps human-readable language names ("English", "Castilian
    Spanish", "Brazilian Portuguese", "Canadian French", ...) to
    ISO 639-2 codes via a parser-local table (per the rules-of-
    engagement memo, each parser knows its own format)
  - preserves the full disc-authored label string in `name` so
    consumers display it raw without the lib guessing further
    structure
  - detects SDH / Forced qualifiers and Commentary / Descriptive
    purposes from substring matches; everything else falls through
    to fill_defaults using BD-spec MPLS data

Verified live on the corpus: disc-07 (Civil War UHD) now matches
parser=dbp with 3 audio + 2 subtitle labels, exactly the count
visible in the disc's authored TextField definitions and what BD
spec MPLS reports.

Limitation: dbp's detect() returns true for ANY top-level .jar in
/BDMV/JAR/ (every BD-J disc has one), since the discriminator
trait function takes only `&UdfFs` and can't read jar contents.
parse() does the real com/dbp/ check — a non-dbp disc gets
parsed-as-dbp, archive_has_dbp returns false, parse() returns
None, and we fall through. Diagnostic noise: parsers_detected
includes "dbp" on non-dbp BD-J discs. Real fix is refactoring the
DetectFn signature to take a SectorReader; deferred.

7 unit tests cover the TextField extraction, language detection
(simple + compound: "Brazilian Portuguese", "Castilian Spanish",
"Canadian French", "Latin American Spanish", "Australian English"
plus the disc-corpus typo "Austrailian English"), SDH/Forced/RNIB
qualifier detection, and Commentary/Descriptive purpose detection.
Don't-guess discipline preserved: unknown languages return ""
(consumer falls back to MPLS spec data via fill_defaults).

src/labels/dbp.rs

@@ -0,0 +1,365 @@
+//! "dbp" framework — Magnolia Pictures BD-J authoring shop (per
+//! `bd-live.magpictures.com` referenced in the disc's
+//! `com/dbp/bluray.MenuXlet.perm`). Detected on UHD discs whose
+//! `/BDMV/JAR/<x>.jar` (top-level, not in a subdir) contains
+//! `com/dbp/` package paths.
+//!
+//! Stream labels live as plain ASCII strings inside compiled `.class`
+//! files in the jar — a quirk of the menu-rendering layer encoding
+//! its TextField positions and content as constant strings the
+//! Java compiler retained in the class string pool. Format observed
+//! in the corpus (Civil War UHD, 2024):
+//!
+//! ```text
+//! LTextField,Audio1,English Dolby Atmos,Fontstrip_Composite,...
+//! RTextField,Audio2,English Descriptive Audio,Fontstrip_Composite,...
+//! HTextField,Subtitle1,English SDH,Fontstrip_Composite,...
+//! ATextField,Subtitle0,None,Fontstrip_Composite,...
+//! ```
+//!
+//! The single uppercase letter before `TextField` is string-pool
+//! prefix noise — the parser anchors on `TextField,` regardless of
+//! what precedes it. `Subtitle0` is the disable-subtitles menu
+//! button and is skipped (not a real subtitle stream).
+//!
+//! Per `(internal)/memory/feedback_label_data_rules.md`: this
+//! parser knows its own format, so we map human-readable language
+//! names ("English", "Spanish", "Canadian French", ...) to ISO 639-2
+//! codes locally. The full disc-authored display string is preserved
+//! in the label `name` field — consumers display it raw without
+//! freemkv guessing further structure.
+
+use super::{LabelPurpose, LabelQualifier, StreamLabel, StreamLabelType};
+use crate::sector::SectorReader;
+use crate::udf::UdfFs;
+
+/// dbp detect can't peek inside a jar without a SectorReader (the
+/// trait function only takes `&UdfFs`), so we trigger on the cheap
+/// signal "any top-level .jar in /BDMV/JAR/." That fires on every
+/// BD-J disc, but parse() does the real `com/dbp/` check and
+/// returns None on a mismatch — so this parser only ever consumes
+/// time on discs that fell through every earlier parser. The
+/// parse-side mismatch is bounded (read one .jar, list central
+/// directory, walk class strings).
+pub fn detect(udf: &UdfFs) -> bool {
+    let Some(jar_dir) = udf.find_dir("/BDMV/JAR") else {
+        return false;
+    };
+    jar_dir
+        .entries
+        .iter()
+        .any(|e| !e.is_dir && e.name.to_lowercase().ends_with(".jar"))
+}
+
+pub fn parse(reader: &mut dyn SectorReader, udf: &UdfFs) -> Option<Vec<StreamLabel>> {
+    let jar_dir = udf.find_dir("/BDMV/JAR")?;
+    for entry in &jar_dir.entries {
+        if entry.is_dir {
+            continue;
+        }
+        if !entry.name.to_lowercase().ends_with(".jar") {
+            continue;
+        }
+        let path = format!("/BDMV/JAR/{}", entry.name);
+        let Ok(bytes) = udf.read_file(reader, &path) else {
+            continue;
+        };
+        let cursor = std::io::Cursor::new(&bytes);
+        let Ok(mut archive) = zip::ZipArchive::new(cursor) else {
+            continue;
+        };
+        if !archive_has_dbp(&mut archive) {
+            continue;
+        }
+        let labels = scan_jar(&mut archive);
+        if !labels.is_empty() {
+            return Some(labels);
+        }
+    }
+    None
+}
+
+fn archive_has_dbp<R: std::io::Read + std::io::Seek>(archive: &mut zip::ZipArchive<R>) -> bool {
+    for i in 0..archive.len() {
+        if let Ok(f) = archive.by_index(i) {
+            if f.name().starts_with("com/dbp/") {
+                return true;
+            }
+        }
+    }
+    false
+}
+
+fn scan_jar<R: std::io::Read + std::io::Seek>(
+    archive: &mut zip::ZipArchive<R>,
+) -> Vec<StreamLabel> {
+    use std::collections::BTreeMap;
+    // BTreeMap so we keep the highest-numbered (last-written) label
+    // for each stream slot deterministic across runs. Entries are
+    // collected from string-pool fragments scattered across hundreds
+    // of obfuscated .class files; the same TextField,Audio1,...
+    // string can appear in multiple classes (button-state variants,
+    // localization fallbacks). Last write wins — they should all
+    // agree on the label text, but the structure is defensive.
+    let mut audios: BTreeMap<u16, String> = BTreeMap::new();
+    let mut subs: BTreeMap<u16, String> = BTreeMap::new();
+
+    for i in 0..archive.len() {
+        let Ok(mut f) = archive.by_index(i) else {
+            continue;
+        };
+        if !f.name().ends_with(".class") {
+            continue;
+        }
+        let mut buf = Vec::new();
+        if std::io::Read::read_to_end(&mut f, &mut buf).is_err() {
+            continue;
+        }
+        for s in extract_printable(&buf) {
+            collect_textfield(&s, &mut audios, &mut subs);
+        }
+    }
+
+    let mut out = Vec::new();
+    for (num, label) in audios {
+        out.push(make_label(num, label, StreamLabelType::Audio));
+    }
+    for (num, label) in subs {
+        out.push(make_label(num, label, StreamLabelType::Subtitle));
+    }
+    out
+}
+
+fn collect_textfield(
+    s: &str,
+    audios: &mut std::collections::BTreeMap<u16, String>,
+    subs: &mut std::collections::BTreeMap<u16, String>,
+) {
+    // Anchor on "TextField," — the prefix character before it varies
+    // (string-pool ordering inside compiled Java) and is irrelevant.
+    let Some(idx) = s.find("TextField,") else {
+        return;
+    };
+    let after = &s[idx + "TextField,".len()..];
+    let mut parts = after.splitn(3, ',');
+    let kind_n = parts.next().unwrap_or("").trim();
+    let label = parts.next().unwrap_or("").trim();
+    if label.is_empty() {
+        return;
+    }
+    if let Some(rest) = kind_n.strip_prefix("Audio") {
+        if let Ok(n) = rest.parse::<u16>() {
+            audios.insert(n, label.to_string());
+        }
+    } else if let Some(rest) = kind_n.strip_prefix("Subtitle") {
+        if let Ok(n) = rest.parse::<u16>() {
+            // Subtitle0 is conventionally the "None / Off" disable
+            // button, not an actual subtitle stream.
+            if n > 0 {
+                subs.insert(n, label.to_string());
+            }
+        }
+    }
+}
+
+fn make_label(num: u16, label: String, stream_type: StreamLabelType) -> StreamLabel {
+    let (language, qualifier, purpose) = parse_attributes(&label);
+    StreamLabel {
+        stream_number: num,
+        stream_type,
+        language,
+        name: label,
+        purpose,
+        qualifier,
+        codec_hint: String::new(),
+        variant: String::new(),
+    }
+}
+
+fn parse_attributes(label: &str) -> (String, LabelQualifier, LabelPurpose) {
+    let lower = label.to_lowercase();
+    let language = detect_language(&lower);
+    let qualifier = if lower.contains("sdh") {
+        LabelQualifier::Sdh
+    } else if lower.contains("descriptive service") || lower.contains(" rnib") {
+        LabelQualifier::DescriptiveService
+    } else if lower.contains("forced") {
+        LabelQualifier::Forced
+    } else {
+        LabelQualifier::None
+    };
+    let purpose = if lower.contains("commentary") {
+        LabelPurpose::Commentary
+    } else if lower.contains("descriptive") || lower.contains("audio description") {
+        LabelPurpose::Descriptive
+    } else {
+        LabelPurpose::Normal
+    };
+    (language, qualifier, purpose)
+}
+
+/// Map English-language label tokens to ISO 639-2 codes. Keep this
+/// list conservative — only common tokens we've actually observed
+/// or that have a canonical mapping. Returns "" when the token
+/// isn't recognized; the consumer falls back to fill_defaults reading
+/// MPLS spec language codes.
+fn detect_language(lower: &str) -> String {
+    // Compound tokens first (multi-word language names).
+    for (needle, code) in [
+        ("brazilian portuguese", "por"),
+        ("euro portuguese", "por"),
+        ("castilian spanish", "spa"),
+        ("latin american spanish", "spa"),
+        ("canadian french", "fra"),
+        ("parisian french", "fra"),
+        ("australian english", "eng"),
+        ("austrailian english", "eng"), // disc-corpus typo, keep matching
+    ] {
+        if lower.contains(needle) {
+            return code.to_string();
+        }
+    }
+    // Then bare tokens. Order matters where one is prefix of another.
+    for (needle, code) in [
+        ("english", "eng"),
+        ("spanish", "spa"),
+        ("french", "fra"),
+        ("german", "deu"),
+        ("italian", "ita"),
+        ("japanese", "jpn"),
+        ("chinese", "zho"),
+        ("portuguese", "por"),
+        ("polish", "pol"),
+        ("czech", "ces"),
+        ("hungarian", "hun"),
+        ("dutch", "nld"),
+        ("korean", "kor"),
+        ("arabic", "ara"),
+        ("hindi", "hin"),
+        ("turkish", "tur"),
+        ("thai", "tha"),
+        ("swedish", "swe"),
+        ("norwegian", "nor"),
+        ("danish", "dan"),
+        ("finnish", "fin"),
+        ("hebrew", "heb"),
+        ("russian", "rus"),
+    ] {
+        if lower.split_whitespace().next() == Some(needle)
+            || lower.split_whitespace().any(|w| w == needle)
+        {
+            return code.to_string();
+        }
+    }
+    String::new()
+}
+
+fn extract_printable(data: &[u8]) -> Vec<String> {
+    let mut out = Vec::new();
+    let mut current = String::new();
+    for &b in data {
+        if (0x20..0x7f).contains(&b) {
+            current.push(b as char);
+        } else {
+            if current.len() >= 5 {
+                out.push(current.clone());
+            }
+            current.clear();
+        }
+    }
+    if current.len() >= 5 {
+        out.push(current);
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn collect_extracts_audio_and_subtitle_indices() {
+        let mut audios = std::collections::BTreeMap::new();
+        let mut subs = std::collections::BTreeMap::new();
+        let lines = [
+            "LTextField,Audio1,English Dolby Atmos,Fontstrip_Composite,296,763,275,25,left",
+            "RTextField,Audio2,English Descriptive Audio,Fontstrip_Composite,296,803,275,25,left",
+            "RTextField,Audio3,Spanish 5.1 Dolby Digital,Fontstrip_Composite,296,843,275,25,left",
+            "ATextField,Subtitle0,None,Fontstrip_Composite,1312,843,275,25,left",
+            "HTextField,Subtitle1,English SDH,Fontstrip_Composite,1312,763,275,25,left",
+            "DTextField,Subtitle2,Spanish,Fontstrip_Composite,1312,803,275,25,left",
+        ];
+        for s in &lines {
+            collect_textfield(s, &mut audios, &mut subs);
+        }
+        assert_eq!(audios.len(), 3);
+        assert_eq!(audios[&1], "English Dolby Atmos");
+        assert_eq!(audios[&2], "English Descriptive Audio");
+        assert_eq!(audios[&3], "Spanish 5.1 Dolby Digital");
+        // Subtitle0 ("None") is skipped — disable button, not a stream.
+        assert_eq!(subs.len(), 2);
+        assert_eq!(subs[&1], "English SDH");
+        assert_eq!(subs[&2], "Spanish");
+    }
+
+    #[test]
+    fn collect_ignores_non_textfield_strings() {
+        let mut audios = std::collections::BTreeMap::new();
+        let mut subs = std::collections::BTreeMap::new();
+        for s in [
+            "GraphicButton,SU_Audio",
+            "AudioMenu",
+            "CommentaryMenuAlternateScenes",
+            "PrimaryAudioControl",
+        ] {
+            collect_textfield(s, &mut audios, &mut subs);
+        }
+        assert!(audios.is_empty());
+        assert!(subs.is_empty());
+    }
+
+    #[test]
+    fn parse_attributes_recognizes_sdh() {
+        let (lang, qual, purp) = parse_attributes("English SDH");
+        assert_eq!(lang, "eng");
+        assert_eq!(qual, LabelQualifier::Sdh);
+        assert_eq!(purp, LabelPurpose::Normal);
+    }
+
+    #[test]
+    fn parse_attributes_recognizes_descriptive_audio() {
+        let (lang, qual, purp) = parse_attributes("English Descriptive Audio");
+        assert_eq!(lang, "eng");
+        assert_eq!(qual, LabelQualifier::None);
+        assert_eq!(purp, LabelPurpose::Descriptive);
+    }
+
+    #[test]
+    fn parse_attributes_recognizes_commentary() {
+        let (lang, qual, purp) = parse_attributes("English Director's Commentary");
+        assert_eq!(lang, "eng");
+        assert_eq!(qual, LabelQualifier::None);
+        assert_eq!(purp, LabelPurpose::Commentary);
+    }
+
+    #[test]
+    fn parse_attributes_recognizes_compound_languages() {
+        assert_eq!(parse_attributes("Brazilian Portuguese 5.1").0, "por");
+        assert_eq!(parse_attributes("Castilian Spanish").0, "spa");
+        assert_eq!(parse_attributes("Canadian French Dolby Digital").0, "fra");
+        assert_eq!(parse_attributes("Latin American Spanish").0, "spa");
+    }
+
+    #[test]
+    fn parse_attributes_returns_empty_for_unknown_language() {
+        // Don't guess. Per the rules-of-engagement.
+        assert_eq!(parse_attributes("Klingon Dolby Atmos").0, "");
+    }
+
+    #[test]
+    fn parse_attributes_recognizes_rnib_descriptive_service() {
+        let (lang, qual, _) = parse_attributes("English RNIB");
+        assert_eq!(lang, "eng");
+        assert_eq!(qual, LabelQualifier::DescriptiveService);
+    }
+}