diff --git a/src/core/builtins/builtins_request.ml b/src/core/builtins/builtins_request.ml
index 9a6daa8b5f..3829033ad3 100644
--- a/src/core/builtins/builtins_request.ml
+++ b/src/core/builtins/builtins_request.ml
@@ -110,6 +110,12 @@ let _ =
         Some
           "Limit in seconds to the duration of the request resolution. \
            Defaults to `settings.request.timeout` when `null`." );
+      ( "content_type",
+        Lang.nullable_t (Lang.source_t (Lang.univ_t ())),
+        Some Lang.null,
+        Some
+          "Check that the request can decode content suitable for the given \
+           source." );
       ("", Request.Value.t, None, None);
     ]
     Lang.bool_t
@@ -121,8 +127,17 @@ let _ =
       let timeout =
         Lang.to_valued_option Lang.to_float (List.assoc "timeout" p)
       in
+      let source =
+        Lang.to_valued_option Lang.to_source (List.assoc "content_type" p)
+      in
       let r = Request.Value.of_value (List.assoc "" p) in
-      Lang.bool (try Request.resolve ?timeout r = `Resolved with _ -> false))
+      Lang.bool
+        (match (Request.resolve ?timeout r, source) with
+          | `Resolved, Some s -> (
+              try Request.get_decoder ~ctype:s#content_type r <> None
+              with _ -> false)
+          | `Resolved, None -> true
+          | _ | (exception _) -> false))
 
 let _ =
   Lang.add_builtin ~base:request "metadata" ~category:`Liquidsoap
@@ -310,8 +325,8 @@ class process ~name r =
         ~name ~priority:`Non_blocking
         ~retry_delay:(fun _ -> 0.1)
         ~available:(fun _ -> true)
+        ~prefetch:1 ~timeout:None ~synchronous:true
         (Lang.val_fun [] (fun _ -> Lang.null))
-        1 None
 
     initializer
       self#on_wake_up (fun () ->
diff --git a/src/core/sources/request_dynamic.ml b/src/core/sources/request_dynamic.ml
index b3aa692b2c..4f16c3d1c0 100644
--- a/src/core/sources/request_dynamic.ml
+++ b/src/core/sources/request_dynamic.ml
@@ -39,6 +39,8 @@ type handler = {
   close : unit -> unit;
 }
 
+type task = { notify : unit -> unit; stop : unit -> unit }
+
 let log_failed_request (log : Log.t) request ans =
   log#important "Could not resolve request %s: %s."
     (Request.initial_uri request)
@@ -47,12 +49,6 @@ let log_failed_request (log : Log.t) request ans =
       | `Timeout -> "timeout"
       | `Resolved -> "file could not be decoded with the correct content")
 
-let extract_queued_params p =
-  let l = Lang.to_valued_option Lang.to_int (List.assoc "prefetch" p) in
-  let l = Option.value ~default:conf_prefetch#get l in
-  let t = Lang.to_valued_option Lang.to_float (List.assoc "timeout" p) in
-  (l, t)
-
 let should_fail = Atomic.make false
 
 let () =
@@ -60,7 +56,7 @@ let () =
       Atomic.set should_fail true)
 
 class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
-  (f : Lang.value) prefetch timeout =
+  ~prefetch ~synchronous ~timeout f =
   let available () = (not (Atomic.get should_fail)) && available () in
   object (self)
     inherit source ~name ()
@@ -180,17 +176,16 @@ class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
     method seek_source = (self :> Source.source)
     method abort_track = Atomic.set should_skip true
 
+    method private is_request_ready =
+      self#current <> None || try self#fetch_request with _ -> false
+
     method can_generate_frame =
-      let is_ready =
-        (fun () ->
-          self#current <> None || try self#fetch_request with _ -> false)
-          ()
-      in
-      match is_ready with
+      match self#is_request_ready with
         | true -> true
         | false ->
             if available () then self#notify_new_request;
-            false
+            (* Try one more time in case a new request was queued above. *)
+            self#is_request_ready
 
     val retrieved : queue_item Queue.t = Queue.create ()
     method private queue_size = Queue.length retrieved
@@ -219,11 +214,24 @@ class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
 
     initializer
       self#on_wake_up (fun () ->
-          let t = Duppy.Async.add Tutils.scheduler ~priority self#feed_queue in
-          Duppy.Async.wake_up t;
+          let task =
+            if synchronous then
+              {
+                notify = (fun () -> self#synchronous_feed_queue);
+                stop = (fun () -> ());
+              }
+            else (
+              let t =
+                Duppy.Async.add Tutils.scheduler ~priority self#feed_queue
+              in
+              {
+                notify = (fun () -> Duppy.Async.wake_up t);
+                stop = (fun () -> Duppy.Async.stop t);
+              })
+          in
           assert (
             Atomic.compare_and_set state `Sleeping
-              (`Started (Unix.gettimeofday (), t))))
+              (`Started (Unix.gettimeofday (), task))))
 
     method private clear_retrieved =
       let rec clear () =
@@ -238,8 +246,8 @@ class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
     initializer
       self#on_sleep (fun () ->
           match Atomic.exchange state `Sleeping with
-            | `Started (_, t) ->
-                Duppy.Async.stop t;
+            | `Started (_, { stop }) ->
+                stop ();
                 (* No more feeding task, we can go to sleep. *)
                 self#end_request;
                 self#log#info "Cleaning up request queue...";
@@ -250,8 +258,7 @@ class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
       opportunity to feed the queue, in case it is sleeping. *)
     method private notify_new_request =
       match Atomic.get state with
-        | `Started (d, t) when d <= Unix.gettimeofday () ->
-            Duppy.Async.wake_up t
+        | `Started (d, { notify }) when d <= Unix.gettimeofday () -> notify ()
         | _ -> ()
 
     (** The body of the feeding task *)
@@ -266,6 +273,11 @@ class dynamic ?(name = "request.dynamic") ~priority ~retry_delay ~available
                   d)
         | _ -> -1.
 
+    method private synchronous_feed_queue =
+      match self#feed_queue () with
+        | 0. -> self#synchronous_feed_queue
+        | _ -> ()
+
     method fetch =
       try
         let r =
@@ -350,6 +362,12 @@ let _ =
         Some
           "Whether some new requests are available (when set to false, it \
            stops after current playing request)." );
+      ( "synchronous",
+        Lang.bool_t,
+        Some (Lang.bool false),
+        Some
+          "If `true`, new requests are prepared as needed instead of using an \
+           asynchronous queue." );
       ( "prefetch",
         Lang.nullable_t Lang.int_t,
         Some Lang.null,
@@ -435,5 +453,13 @@ let _ =
           | "non_blocking" -> `Non_blocking
           | n -> `Named n
       in
-      let l, t = extract_queued_params p in
-      new dynamic ~available ~priority ~retry_delay f l t)
+      let prefetch =
+        Lang.to_valued_option Lang.to_int (List.assoc "prefetch" p)
+      in
+      let prefetch = Option.value ~default:conf_prefetch#get prefetch in
+      let synchronous = Lang.to_bool (List.assoc "synchronous" p) in
+      let timeout =
+        Lang.to_valued_option Lang.to_float (List.assoc "timeout" p)
+      in
+      new dynamic
+        ~available ~priority ~retry_delay ~prefetch ~timeout ~synchronous f)
diff --git a/src/libs/extra/native.liq b/src/libs/extra/native.liq
index 4cfdfa5f86..a7ead829e5 100644
--- a/src/libs/extra/native.liq
+++ b/src/libs/extra/native.liq
@@ -89,6 +89,7 @@ def native.request.dynamic(%argsof(request.dynamic), f) =
   ignore(available)
   ignore(timeout)
   ignore(native)
+  ignore(synchronous)
 
   def f() =
     try
diff --git a/src/libs/request.liq b/src/libs/request.liq
index c2dc9ade09..130dc8de86 100644
--- a/src/libs/request.liq
+++ b/src/libs/request.liq
@@ -280,7 +280,7 @@ def request.single(
 ) =
   id = string.id.default(default="single", id)
 
-  fallible = fallible ?? getter.is_constant(r)
+  fallible = fallible ?? not getter.is_constant(r)
 
   infallible =
     if
@@ -302,9 +302,20 @@ def request.single(
       false
     end
 
+  if
+    not fallible and not infallible
+  then
+    log.severe(
+      label=id,
+      "Source was marked a infallible but its request is not a static file. The \
+       source is considered fallible for backward compatibility but this will \
+       fail in future versions!"
+    )
+  end
+
   static_request = ref(null())
 
-  def on_wake_up() =
+  def on_wake_up(s) =
     if
       infallible
     then
@@ -315,8 +326,9 @@ def request.single(
         label=id,
         "#{uri} is static, resolving once for all..."
       )
+
       if
-        not request.resolve(initial_request, timeout=timeout)
+        not request.resolve(initial_request, timeout=timeout, content_type=s)
       then
         request.destroy(initial_request)
         error.raise(
@@ -339,20 +351,35 @@ def request.single(
   end
 
   def next() =
-    def next() =
-      static_request() ?? getter.get(r)
-    end
+    static_request() ?? getter.get(r)
+  end
 
-    s = request.dynamic(prefetch=prefetch, thread_queue=thread_queue, next)
-    if infallible then s.set_queue([next()]) end
-    s
+  def mk_source(id) =
+    request.dynamic(
+      id=id,
+      prefetch=prefetch,
+      thread_queue=thread_queue,
+      synchronous=infallible,
+      next
+    )
   end
 
+  # We want to mark infallible source as such. `source.dynamic` is a nice
+  # way to do it as it will raise a user-friendly error in case the underlying
+  # source does not respect the conditions for being infallible.
   s =
-    source.dynamic(
-      id=id, infallible=infallible, self_sync=false, track_sensitive=true, next
-    )
-  s.on_wake_up(on_wake_up)
+    if
+      infallible
+    then
+      s = mk_source("#{id}.actual")
+      source.dynamic(
+        id=id, infallible=infallible, self_sync=false, track_sensitive=true, {s}
+      )
+    else
+      mk_source(id)
+    end
+
+  s.on_wake_up(fun () -> on_wake_up(s))
   s.on_shutdown(on_shutdown)
   (s : source_methods)
 end