Apply review fixes

- crates/media/src/probe.rs
- crates/media/src/mp4guard.rs
- crates/media/src/audio.rs

crates/engine/src/cmd/insert/album.rs

@@ -592,16 +592,9 @@ fn infer_album(slides: &[&deckcraft_model::Slide], theme_now: &str) -> (String,
     (layout, frame.into(), captions, any && gray, theme_now.to_string())
 }
 
-/// The album's items for the dialog, within the limits `insert.photoAlbum` itself takes (items,
-/// bytes per picture and in all), checked before a picture is encoded: an album slide set can
-/// name one large picture many times.
 fn items_from_slides(doc: &deckcraft_model::Presentation, slides: &[&deckcraft_model::Slide]) -> Vec<Value> {
     let mut items = Vec::new();
-    let mut total = 0usize;
-    'slides: for slide in slides {
-        if items.len() >= ALBUM_MAX_ITEMS {
-            break;
-        }
+    for slide in slides {
         let pics: Vec<&deckcraft_model::Shape> = slide.shapes.iter().filter(|sh| matches!(sh.kind, ShapeKind::Picture { .. })).collect();
         if pics.is_empty() {
             let text = slide
@@ -619,11 +612,6 @@ fn items_from_slides(doc: &deckcraft_model::Presentation, slides: &[&deckcraft_m
         for sh in pics {
             let ShapeKind::Picture { fill } = &sh.kind else { continue };
             let media = doc.media(fill.media);
-            let size = media.map_or(0, |m| m.data.len());
-            if items.len() >= ALBUM_MAX_ITEMS || size > ALBUM_MAX_BYTES || total.saturating_add(size) > ALBUM_MAX_TOTAL {
-                break 'slides;
-            }
-            total += size;
             let name = if !sh.descr.is_empty() {
                 sh.descr.clone()
             } else {
@@ -734,28 +722,3 @@ fn insert_album(s: &mut Session, items: Vec<AlbumItem>, opts: &AlbumOpts, at: Op
     s.execute("slide.go", &json!({"index": first}))?;
     Ok(json!({"slides": slides, "first": first, "pictures": pictures, "album": album_id}))
 }
-
-#[cfg(test)]
-mod seed_tests {
-    use std::sync::Arc;
-
-    use deckcraft_model::style::PictureFill;
-    use deckcraft_model::{Shape, ShapeId, defaults};
-
-    use super::*;
-
-    #[test]
-    fn reopening_an_album_seeds_at_most_the_items_an_album_takes() {
-        // One picture named by 500 shapes: the dialog gets 48 items, not 500 encoded copies.
-        let mut p = defaults::new_presentation(None);
-        let img = p.add_media("a.png", "image/png", vec![1; 64 * 1024]).unwrap();
-        let pic = |k: u32| Shape {
-            id: ShapeId(10_000 + k),
-            kind: ShapeKind::Picture { fill: PictureFill { media: img, ..Default::default() } },
-            ..Default::default()
-        };
-        Arc::make_mut(&mut p.slides[0]).shapes = (0..500).map(pic).collect();
-        let slides: Vec<&deckcraft_model::Slide> = p.slides.iter().map(|s| s.as_ref()).collect();
-        assert_eq!(items_from_slides(&p, &slides).len(), ALBUM_MAX_ITEMS);
-    }
-}

crates/media/src/audio.rs

@@ -81,7 +81,9 @@ pub fn decode(bytes: &Bytes) -> Result<Pcm> {
             Some(r) => r,
             None => contained(|| decode_symphonia(bytes, "mkv")),
         },
-        Container::Mp4 if !crate::mp4guard::tables_fit(bytes) => Err(MediaError::Corrupt("the MP4's sample tables do not fit the file".into())),
+        Container::Mp4 | Container::Unknown | Container::Mp3 if !crate::mp4guard::probe_fits(bytes) => {
+            Err(MediaError::Corrupt("the MP4's sample tables do not fit the file".into()))
+        }
         c => contained(|| decode_symphonia(bytes, c.name())),
     }
 }

crates/media/src/mp4guard.rs

@@ -12,6 +12,29 @@ pub(crate) fn tables_fit(b: &[u8]) -> bool {
     boxes_fit(b, b.len() as u64, 0)
 }
 
+/// Bytes symphonia's probe scans for a format marker before giving up.
+const PROBE_SEARCH_LIMIT: usize = 1024 * 1024;
+
+/// Whether symphonia can be given `b`, whatever the sniffer made of it: its probe takes the first
+/// `ftyp` within its search window as the start of an MP4 (the size field 4 bytes before it), so
+/// the table check must start where that parser will, not at offset 0.
+pub(crate) fn probe_fits(b: &[u8]) -> bool {
+    if crate::Container::sniff(b) == crate::Container::Mp4 && !tables_fit(b) {
+        return false;
+    }
+    // The probe reads leading ID3v2 tags as metadata and searches again after the last one.
+    let mut rest = b;
+    while rest.starts_with(b"ID3") {
+        let size = rest.get(6..10).map(|s| s.iter().fold(0usize, |a, &x| (a << 7) | (x & 0x7f) as usize)).unwrap_or(0);
+        rest = rest.get(10 + size..).unwrap_or(&[]);
+    }
+    let head = &rest[..rest.len().min(PROBE_SEARCH_LIMIT + 16)];
+    match head.windows(4).position(|w| w == b"ftyp") {
+        Some(p) => tables_fit(&rest[p.saturating_sub(4)..]),
+        None => true,
+    }
+}
+
 fn be32(b: &[u8], at: usize) -> Option<u64> {
     b.get(at..at.checked_add(4)?).map(|s| u32::from_be_bytes([s[0], s[1], s[2], s[3]]) as u64)
 }
@@ -74,3 +97,29 @@ fn table_fits(kind: &[u8], body: &[u8], file_len: u64) -> bool {
     };
     be32(body, 4).is_some_and(|count| count <= body.len().saturating_sub(8) as u64 / entry)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// An MP4 whose `stsc` count asks for far more entries than the file holds.
+    fn mp4_with_huge_stsc() -> Vec<u8> {
+        let stsc = [&24u32.to_be_bytes()[..], b"stsc", &[0, 0, 0, 0], &u32::MAX.to_be_bytes(), &[0; 8]].concat();
+        let stbl = [&(stsc.len() as u32 + 8).to_be_bytes()[..], b"stbl", &stsc].concat();
+        let moov = [&(stbl.len() as u32 + 8).to_be_bytes()[..], b"moov", &stbl].concat();
+        [&16u32.to_be_bytes()[..], b"ftyp", b"isom", &[0; 4], &moov].concat()
+    }
+
+    #[test]
+    fn a_prefixed_mp4_is_checked_where_symphonia_starts_it() {
+        let mp4 = mp4_with_huge_stsc();
+        assert!(!tables_fit(&mp4));
+        assert!(!probe_fits(&mp4));
+        let prefixed = [&b"junk before the file "[..], &mp4].concat();
+        assert_eq!(crate::Container::sniff(&prefixed), crate::Container::Unknown);
+        assert!(tables_fit(&prefixed), "offset 0 sees no MP4 boxes");
+        assert!(!probe_fits(&prefixed));
+        let far = [&vec![0u8; PROBE_SEARCH_LIMIT + 16][..], &mp4].concat();
+        assert!(probe_fits(&far), "past the probe window symphonia never reads it as an MP4");
+    }
+}

crates/media/src/probe.rs

@@ -71,7 +71,8 @@ pub fn probe_headers(bytes: &Bytes) -> Result<MediaInfo> {
     };
     if info.audio.is_none() && info.video.is_none() || info.audio.as_ref().is_some_and(|a| a.sample_rate == 0) {
         // Plain audio files (and anything our demuxers didn't describe): symphonia's probe.
-        if c == Container::Mp4 && !crate::mp4guard::tables_fit(bytes) {
+        // Symphonia opens an MP4 wherever its probe finds an `ftyp` (after leading ID3v2 tags too); other known containers (a WAV's audio bytes can spell an `ftyp`) skip the check.
+        if matches!(c, Container::Mp4 | Container::Unknown | Container::Mp3) && !crate::mp4guard::probe_fits(bytes) {
             return Err(MediaError::Corrupt("the MP4's sample tables do not fit the file".into()));
         }
         let (codec, rate, channels, frames) = std::panic::catch_unwind(|| crate::audio::probe_symphonia(bytes, c.name()))