diff --git a/crates/engine/src/cmd/file.rs b/crates/engine/src/cmd/file.rs
index ba567571..83e730d9 100644
--- a/crates/engine/src/cmd/file.rs
+++ b/crates/engine/src/cmd/file.rs
@@ -1,6 +1,10 @@
 //! File menu: new, open, save, export, close, properties.
 
-use deckcraft_model::{Presentation, defaults};
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use deckcraft_media::MediaInfo;
+use deckcraft_model::{MediaId, MediaItem, Presentation, Shape, ShapeKind, defaults};
 use serde_json::{Value, json};
 
 use super::*;
@@ -156,6 +160,7 @@ fn open_other(name: &str, bytes: &[u8]) -> Result<(Presentation, Vec<String>)> {
     if deckcraft_pptx::sniff(bytes) {
         let (mut p, lost_slides) = deckcraft_pptx::import_checked(bytes).map_err(|e| EngineError::Other(e.to_string()))?;
         deckcraft_format::repair(&mut p);
+        probe_clips(&mut p);
         return Ok((p, lost_slides));
     }
     if deckcraft_pptx::is_encrypted(bytes) {
@@ -178,6 +183,42 @@ fn open_other(name: &str, bytes: &[u8]) -> Result<(Presentation, Vec<String>)> {
     Err(EngineError::Other(format!("{name}: not a presentation DeckCraft can read")))
 }
 
+/// Fill in each audio and video clip's length and picture size from its bytes: a `.pptx` doesn't
+/// store them. Headers only, so opening never decodes a whole audio file.
+fn probe_clips(p: &mut Presentation) {
+    fn rec(shapes: &mut [Shape], media: &[MediaItem], probed: &mut HashMap<MediaId, Option<MediaInfo>>, depth: usize) {
+        if depth > 64 {
+            return;
+        }
+        for s in shapes {
+            if let ShapeKind::Media(m) = &mut s.kind
+                && (m.duration_ms == 0 || m.width == 0 && m.height == 0)
+                && let Some(info) = probed
+                    .entry(m.media)
+                    .or_insert_with(|| media.iter().find(|i| i.id == m.media).and_then(|i| deckcraft_media::probe_headers(&i.data).ok()))
+            {
+                if m.duration_ms == 0 {
+                    m.duration_ms = info.duration_ms.min(u32::MAX as u64) as u32;
+                }
+                if m.width == 0
+                    && m.height == 0
+                    && let Some(v) = &info.video
+                {
+                    (m.width, m.height) = (v.width, v.height);
+                }
+            }
+            if let Some(children) = s.children_mut() {
+                rec(children, media, probed, depth + 1);
+            }
+        }
+    }
+    let mut probed = HashMap::new();
+    // Just read, so no slide is shared yet and `make_mut` doesn't copy.
+    for slide in &mut p.slides {
+        rec(&mut Arc::make_mut(slide).shapes, &p.media, &mut probed, 0);
+    }
+}
+
 pub fn add_opened(s: &mut Session, name: &str, path: Option<String>, p: Presentation) -> usize {
     let title = std::path::Path::new(name).file_stem().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| name.to_string());
     crate::fonts::install_embedded_fonts(&p);
diff --git a/crates/engine/src/cmd/media.rs b/crates/engine/src/cmd/media.rs
index d9a3147d..85ed6c3f 100644
--- a/crates/engine/src/cmd/media.rs
+++ b/crates/engine/src/cmd/media.rs
@@ -228,6 +228,21 @@ mod tests {
         assert!(s.execute("media.posterFrame", &json!({})).is_err(), "audio has no poster frame");
     }
 
+    #[test]
+    fn a_video_reopened_from_pptx_keeps_its_length_and_size() {
+        let mut s = Session::with_new();
+        let clip = include_bytes!("../../../media/tests/fixtures/clip-h264.mp4");
+        s.execute("insert.video", &json!({"name": "clip.mp4", "data": base64_encode(clip)})).expect("insert");
+        let before = s.execute("media.info", &json!({})).expect("info");
+        assert!(before["durationMs"].as_u64().is_some_and(|ms| ms > 0));
+        let saved = s.execute("file.saveBytes", &json!({"format": "pptx"})).expect("save");
+        s.execute("file.openBytes", &json!({"name": "deck.pptx", "data": saved["data"]})).expect("open");
+        let after = s.execute("media.info", &json!({})).expect("info");
+        for key in ["durationMs", "width", "height"] {
+            assert_eq!(after[key], before[key], "{key}");
+        }
+    }
+
     #[test]
     fn media_commands_need_media() {
         let mut s = Session::with_new();
diff --git a/crates/media/src/lib.rs b/crates/media/src/lib.rs
index dc1a892b..1f924820 100644
--- a/crates/media/src/lib.rs
+++ b/crates/media/src/lib.rs
@@ -31,7 +31,7 @@ pub use audio::Pcm;
 pub use clip::ClipParams;
 pub use feed::VideoFeed;
 pub use player::{AudioOut, PlayState, Player, VoiceSpec, VoiceStatus};
-pub use probe::{AudioInfo, MediaInfo, VideoInfo, probe};
+pub use probe::{AudioInfo, MediaInfo, VideoInfo, probe, probe_headers};
 pub use video::{Frame, VideoDecoder, poster_frame, poster_png};
 
 /// Shared media bytes (the model's `MediaItem::data`).
diff --git a/crates/media/src/probe.rs b/crates/media/src/probe.rs
index 2453317a..97d9a751 100644
--- a/crates/media/src/probe.rs
+++ b/crates/media/src/probe.rs
@@ -48,6 +48,19 @@ fn ms(secs: f64) -> u64 {
 
 /// Probe `bytes`.
 pub fn probe(bytes: &Bytes) -> Result<MediaInfo> {
+    let mut info = probe_headers(bytes)?;
+    if info.duration_ms == 0 && info.audio.as_ref().is_some_and(|a| a.decodable) && info.video.is_none() {
+        // No length in the header (raw MP3 / ADTS without an index): decode to measure.
+        if let Ok(pcm) = crate::audio::decode(bytes) {
+            info.duration_ms = ms(pcm.duration());
+        }
+    }
+    Ok(info)
+}
+
+/// [`probe`] from the headers alone, without decoding: a raw MP3 or ADTS stream without an
+/// index reports a `duration_ms` of 0.
+pub fn probe_headers(bytes: &Bytes) -> Result<MediaInfo> {
     let c = Container::sniff(bytes);
     let mut info = match c {
         Container::Mp4 => probe_mp4(bytes)?,
@@ -73,12 +86,6 @@ pub fn probe(bytes: &Bytes) -> Result<MediaInfo> {
             info.duration_ms = ms(n as f64 / rate as f64);
         }
     }
-    if info.duration_ms == 0 && info.audio.as_ref().is_some_and(|a| a.decodable) && info.video.is_none() {
-        // No length in the header (raw MP3 / ADTS without an index): decode to measure.
-        if let Ok(pcm) = crate::audio::decode(bytes) {
-            info.duration_ms = ms(pcm.duration());
-        }
-    }
     Ok(info)
 }