support segmented mp4s

This is intended to support HTML5 Media Source Extensions, which I expect to
be the most practical way to make a good web UI with a proper scrub bar and
such.

This feature has had very limited testing on Chrome and Firefox, and that was
not entirely successful. More work is needed before it's usable, but this
seems like a helpful progress checkpoint.

src/web.rs

@@ -69,10 +69,12 @@ lazy_static! {
 }
 
 enum Path {
-    CamerasList,              // "/" or "/cameras/"
-    Camera(Uuid),             // "/cameras/<uuid>/"
-    CameraRecordings(Uuid),   // "/cameras/<uuid>/recordings"
-    CameraViewMp4(Uuid),      // "/cameras/<uuid>/view.mp4"
+    CamerasList,                 // "/" or "/cameras/"
+    InitSegment([u8; 20]),       // "/init/<sha1>.mp4"
+    Camera(Uuid),                // "/cameras/<uuid>/"
+    CameraRecordings(Uuid),      // "/cameras/<uuid>/recordings"
+    CameraViewMp4(Uuid),         // "/cameras/<uuid>/view.mp4"
+    CameraViewMp4Segment(Uuid),  // "/cameras/<uuid>/view.m4s"
     NotFound,
 }
 
@@ -80,6 +82,15 @@ fn decode_path(path: &str) -> Path {
     if path == "/" {
         return Path::CamerasList;
     }
+    if path.starts_with("/init/") {
+        if path.len() != 50 || !path.ends_with(".mp4") {
+            return Path::NotFound;
+        }
+        if let Ok(sha1) = strutil::dehex(&path.as_bytes()[6..46]) {
+            return Path::InitSegment(sha1);
+        }
+        return Path::NotFound;
+    }
     if !path.starts_with("/cameras/") {
         return Path::NotFound;
     }
@@ -102,6 +113,7 @@ fn decode_path(path: &str) -> Path {
         "/" => Path::Camera(uuid),
         "/recordings" => Path::CameraRecordings(uuid),
         "/view.mp4" => Path::CameraViewMp4(uuid),
+        "/view.m4s" => Path::CameraViewMp4Segment(uuid),
         _ => Path::NotFound,
     }
 }
@@ -436,7 +448,20 @@ impl Service {
            .with_body(body))
     }
 
-    fn camera_view_mp4(&self, uuid: Uuid, query: Option<&str>, req: &Request)
+    fn init_segment(&self, sha1: [u8; 20], req: &Request) -> Result<Response<slices::Body>, Error> {
+        let mut builder = mp4::FileBuilder::new(mp4::Type::InitSegment);
+        let db = self.db.lock();
+        for ent in db.video_sample_entries() {
+            if ent.sha1 == sha1 {
+                builder.append_video_sample_entry(ent.clone());
+                let mp4 = builder.build(self.db.clone(), self.dir.clone())?;
+                return Ok(http_entity::serve(mp4, req));
+            }
+        }
+        self.not_found()
+    }
+
+    fn camera_view_mp4(&self, uuid: Uuid, type_: mp4::Type, query: Option<&str>, req: &Request)
                        -> Result<Response<slices::Body>, Error> {
         let camera_id = {
             let db = self.db.lock();
@@ -444,7 +469,7 @@ impl Service {
                            .ok_or_else(|| Error::new("no such camera".to_owned()))?;
             camera.id
         };
-        let mut builder = mp4::FileBuilder::new();
+        let mut builder = mp4::FileBuilder::new(type_);
         if let Some(q) = query {
             for (key, value) in form_urlencoded::parse(q.as_bytes()) {
                 let (key, value) = (key.borrow(), value.borrow());
@@ -556,10 +581,16 @@ impl server::Service for Service {
     fn call(&self, req: Request) -> Self::Future {
         debug!("request on: {}", req.uri());
         let res = match decode_path(req.uri().path()) {
+            Path::InitSegment(sha1) => self.init_segment(sha1, &req),
             Path::CamerasList => self.list_cameras(&req),
             Path::Camera(uuid) => self.camera(uuid, req.uri().query(), &req),
             Path::CameraRecordings(uuid) => self.camera_recordings(uuid, req.uri().query(), &req),
-            Path::CameraViewMp4(uuid) => self.camera_view_mp4(uuid, req.uri().query(), &req),
+            Path::CameraViewMp4(uuid) => {
+                self.camera_view_mp4(uuid, mp4::Type::Normal, req.uri().query(), &req)
+            },
+            Path::CameraViewMp4Segment(uuid) => {
+                self.camera_view_mp4(uuid, mp4::Type::MediaSegment, req.uri().query(), &req)
+            },
             Path::NotFound => self.not_found(),
         };
         future::result(res.map_err(|e| {