From: Romain Beauxis <toots@rastageeks.org>
Date: Wed, 9 Apr 2025 21:30:34 -0500
Subject: Flip default behavior for `metadata.map` strip argument. (#4447)

Applied-Upstream: 30c41bafcceae8d5fd62ae4a79ddc78efb9f7743

---
 CHANGES.md                                     | 14 +++++++++
 src/core/operators/map_metadata.ml             | 40 ++++++++++++++++++++------
 tests/media/ffmpeg_filter_changing_rate.liq    |  2 +-
 tests/regression/AC5109.liq                    |  4 +--
 tests/regression/GH1129.liq                    |  6 ++--
 tests/regression/GH1279.liq                    |  4 +--
 tests/regression/GH1327.liq                    |  6 ++--
 tests/regression/GH4163.liq                    | 17 +++++++++--
 tests/regression/GH4281-2.liq                  | 10 +++++--
 tests/regression/GH4281.liq                    | 10 +++++--
 tests/regression/append-merge.liq              |  4 ++-
 tests/regression/seek_track_map.liq            |  2 +-
 tests/streams/cross-override-end.liq           | 11 +++++--
 tests/streams/cross-override-start.liq         | 11 +++++--
 tests/streams/cross-override.liq               | 11 +++++--
 tests/streams/cross-persist-end-override.liq   | 11 +++++--
 tests/streams/cross-persist-override.liq       | 11 +++++--
 tests/streams/cross-persist-start-override.liq | 11 +++++--
 tests/streams/cross.liq                        | 10 +++++--
 tests/streams/crossfade-plot.liq               |  2 ++
 tests/streams/crossfade.liq                    | 10 +++++--
 tests/streams/fades-overrides.liq              | 11 +++++--
 tests/streams/fades-persistent-override.liq    | 11 +++++--
 tests/streams/hls_id3v2.liq                    |  1 +
 tests/streams/random.liq                       |  4 +--
 tests/streams/rotate.liq                       |  7 ++++-
 26 files changed, 190 insertions(+), 51 deletions(-)

diff --git a/CHANGES.md b/CHANGES.md
index e1228be..fdd7f0b 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,17 @@
+# 2.3.3 (unreleased)
+
+Fixed:
+
+- Do not send empty metadata to shoutcast servers (#4408)
+
+Changed:
+
+- Changed default value of `metadata.map` `strip` argument to `true` and `insert_missing`
+  to `false` Added `settings.metadata.map.strip` and `settings.metadata.map.insert_missing`
+  configuration keys to revert to previous defaults. (#4447)
+
+---
+
 # 2.3.2 (2025-04-01) 🃏

 New:
diff --git a/src/core/operators/map_metadata.ml b/src/core/operators/map_metadata.ml
index f4d18e1..1dfecd3 100644
--- a/src/core/operators/map_metadata.ml
+++ b/src/core/operators/map_metadata.ml
@@ -22,6 +22,22 @@

 open Source

+let conf_metadata =
+  Dtools.Conf.void ~p:(Configure.conf#plug "Metadata") "Metadata settings"
+
+let conf_metadata_map =
+  Dtools.Conf.void ~p:(conf_metadata#plug "map") "Metadata map settings"
+
+let conf_metadata_map_strip =
+  Dtools.Conf.bool
+    ~p:(conf_metadata_map#plug "strip")
+    ~d:true "Default value for the `strip` parameter."
+
+let conf_metadata_map_insert_missing =
+  Dtools.Conf.bool
+    ~p:(conf_metadata_map#plug "insert_missing")
+    ~d:false "Default value for the `insert_missing` parameter."
+
 class map_metadata source rewrite_f insert_missing update strip =
   object (self)
     inherit operator ~name:"metadata.map" [source]
@@ -89,18 +105,20 @@ let register =
           "Update metadata. If false, existing metadata are cleared and only \
            returned values are set as new metadata." );
       ( "strip",
-        Lang.bool_t,
-        Some (Lang.bool false),
+        Lang.nullable_t Lang.bool_t,
+        Some Lang.null,
         Some
           "Completely remove empty metadata. Operates on both empty values and \
-           empty metadata chunk." );
+           empty metadata chunk. Defaults to `settings.metadata.map.strip` \
+           when `null`." );
       ( "insert_missing",
-        Lang.bool_t,
-        Some (Lang.bool true),
+        Lang.nullable_t Lang.bool_t,
+        Some Lang.null,
         Some
           "Treat track beginnings without metadata as having empty ones. The \
            operational order is: create empty if needed, map and strip if \
-           enabled." );
+           enabled. Defaults to `settings.metadata.map.insert_missing` when \
+           `null`." );
       ("", return_t, None, None);
     ]
     ~category:`Track ~descr:"Rewrite metadata on the fly using a function."
@@ -110,6 +128,12 @@ let register =
       assert (field = Frame.Fields.metadata);
       let f = Lang.assoc "" 1 p in
       let update = Lang.to_bool (List.assoc "update" p) in
-      let strip = Lang.to_bool (List.assoc "strip" p) in
-      let missing = Lang.to_bool (List.assoc "insert_missing" p) in
+      let strip = Lang.to_valued_option Lang.to_bool (List.assoc "strip" p) in
+      let strip = Option.value ~default:conf_metadata_map_strip#get strip in
+      let missing =
+        Lang.to_valued_option Lang.to_bool (List.assoc "insert_missing" p)
+      in
+      let missing =
+        Option.value ~default:conf_metadata_map_insert_missing#get missing
+      in
       (field, new map_metadata source f missing update strip))
diff --git a/tests/media/ffmpeg_filter_changing_rate.liq b/tests/media/ffmpeg_filter_changing_rate.liq
index 0df077b..3c79b17 100644
--- a/tests/media/ffmpeg_filter_changing_rate.liq
+++ b/tests/media/ffmpeg_filter_changing_rate.liq
@@ -27,7 +27,7 @@ end
 s = single(fname)
 s' = single(fname2)
 last = single(id="last", fname)
-last = metadata.map(fun (_) -> [("title", "done")], last)
+last = metadata.map(insert_missing=true, fun (_) -> [("title", "done")], last)
 s = sequence([s, s', s, s', s, last, s, s', s])
 s = f(s)
 done = ref(false)
diff --git a/tests/regression/AC5109.liq b/tests/regression/AC5109.liq
index e372c55..a9a768f 100644
--- a/tests/regression/AC5109.liq
+++ b/tests/regression/AC5109.liq
@@ -7,9 +7,9 @@ s = sequence([s1, s2])

 def transition(a, b) =
   s1 = sine(duration=0.5)
-  s1 = metadata.map(fun (_) -> [("type", "s1")], s1)
+  s1 = metadata.map(insert_missing=true, fun (_) -> [("type", "s1")], s1)
   s2 = sine(duration=0.5)
-  s2 = metadata.map(fun (_) -> [("type", "s2")], s2)
+  s2 = metadata.map(insert_missing=true, fun (_) -> [("type", "s2")], s2)
   sequence(
     [(a.source : source), (s1 : source), (s2 : source), (b.source : source)]
   )
diff --git a/tests/regression/GH1129.liq b/tests/regression/GH1129.liq
index 3421ec9..1777a64 100644
--- a/tests/regression/GH1129.liq
+++ b/tests/regression/GH1129.liq
@@ -9,7 +9,7 @@ def m1(_) =
   [("id", "s1")]
 end

-s1 = metadata.map(id="s1", m1, s1)
+s1 = metadata.map(insert_missing=true, id="s1", m1, s1)
 s2_ready = ref(false)
 s2 = switch(id="s2", [({!s2_ready}, blank(duration=0.04))])

@@ -17,14 +17,14 @@ def m2(_) =
   [("id", "s2")]
 end

-s2 = metadata.map(id="s2", m2, s2)
+s2 = metadata.map(insert_missing=true, id="s2", m2, s2)
 s3 = blank(id="s3", duration=0.04)

 def m3(_) =
   [("id", "s3")]
 end

-s3 = metadata.map(id="s3", m3, s3)
+s3 = metadata.map(insert_missing=true, id="s3", m3, s3)

 def f(m) =
   s2_ready := !s2_ready or m["id"] == "s3"
diff --git a/tests/regression/GH1279.liq b/tests/regression/GH1279.liq
index e53143b..f9784a0 100644
--- a/tests/regression/GH1279.liq
+++ b/tests/regression/GH1279.liq
@@ -5,14 +5,14 @@ def m1(_) =
   [("id", "s1")]
 end

-s1 = metadata.map(id="s1", m1, s1)
+s1 = metadata.map(insert_missing=true, id="s1", m1, s1)
 s2 = blank(duration=0.04)

 def m2(_) =
   [("id", "s2")]
 end

-s2 = metadata.map(id="s2", m2, s2)
+s2 = metadata.map(insert_missing=true, id="s2", m2, s2)

 def f(m) =
   selected := list.add(m["id"], !selected)
diff --git a/tests/regression/GH1327.liq b/tests/regression/GH1327.liq
index 037fb6c..891a669 100644
--- a/tests/regression/GH1327.liq
+++ b/tests/regression/GH1327.liq
@@ -8,7 +8,7 @@ def m1(_) =
   [("id", "s1")]
 end

-s1 = metadata.map(id="s1", m1, s1)
+s1 = metadata.map(insert_missing=true, id="s1", m1, s1)

 s2 = blank(duration=0.1)

@@ -16,7 +16,7 @@ def m2(_) =
   [("id", "s2")]
 end

-s2 = metadata.map(id="s2", m2, s2)
+s2 = metadata.map(insert_missing=true, id="s2", m2, s2)

 def f(m) =
   selected := list.add(m["id"], !selected)
@@ -30,7 +30,7 @@ def m_noise(_) =
   [("id", "noise")]
 end

-noise = metadata.map(id="noise", m_noise, noise())
+noise = metadata.map(insert_missing=true, id="noise", m_noise, noise())

 ready = ref(false)

diff --git a/tests/regression/GH4163.liq b/tests/regression/GH4163.liq
index 65cc60a..c4cbe08 100644
--- a/tests/regression/GH4163.liq
+++ b/tests/regression/GH4163.liq
@@ -1,11 +1,17 @@
 first_blank =
   metadata.map(
-    id="first_blank", fun (_) -> [("title", "first_blank")], blank(duration=3.)
+    insert_missing=true,
+    id="first_blank",
+    fun (_) -> [("title", "first_blank")],
+    blank(duration=3.)
   )

 after_blank =
   metadata.map(
-    id="after_blank", fun (_) -> [("title", "after_blank")], sine(duration=10.)
+    insert_missing=true,
+    id="after_blank",
+    fun (_) -> [("title", "after_blank")],
+    sine(duration=10.)
   )

 blank_sequence = sequence(id="blank_sequence", [first_blank, after_blank])
@@ -14,7 +20,12 @@ blank_strip =
   blank.strip(id="blank_strip", max_blank=5., start_blank=true, blank_sequence)

 fallback_sine =
-  metadata.map(id="fallback_sine", fun (_) -> [("title", "fallback")], sine())
+  metadata.map(
+    insert_missing=true,
+    id="fallback_sine",
+    fun (_) -> [("title", "fallback")],
+    sine()
+  )

 s =
   fallback(
diff --git a/tests/regression/GH4281-2.liq b/tests/regression/GH4281-2.liq
index 5a0176c..43c942e 100644
--- a/tests/regression/GH4281-2.liq
+++ b/tests/regression/GH4281-2.liq
@@ -1,8 +1,14 @@
 d = sequence([sine(duration=3.), sine(duration=3.)])
-d = metadata.map(update=false, (fun (_) -> [("title", "delay")]), d)
+d =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "delay")]), d
+  )

 f = sequence([sine(duration=3.), sine(duration=3.)])
-f = metadata.map(update=false, (fun (_) -> [("title", "fallback")]), f)
+f =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "fallback")]), f
+  )

 s = fallback([delay(initial=true, 1., d), f])

diff --git a/tests/regression/GH4281.liq b/tests/regression/GH4281.liq
index 3b0dade..e371c8f 100644
--- a/tests/regression/GH4281.liq
+++ b/tests/regression/GH4281.liq
@@ -1,8 +1,14 @@
 d = sequence([sine(duration=3.), sine(duration=3.)])
-d = metadata.map(update=false, (fun (_) -> [("title", "delay")]), d)
+d =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "delay")]), d
+  )

 f = sequence([sine(duration=3.), sine(duration=3.)])
-f = metadata.map(update=false, (fun (_) -> [("title", "fallback")]), f)
+f =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "fallback")]), f
+  )

 s = fallback([delay(1., d), f])

diff --git a/tests/regression/append-merge.liq b/tests/regression/append-merge.liq
index 28065f9..b80ed92 100644
--- a/tests/regression/append-merge.liq
+++ b/tests/regression/append-merge.liq
@@ -2,7 +2,9 @@ music = chop(every=1., metadata=[("source", "s1")], sine(amplitude=0.1, 440.))

 def next(_) =
   s = sine(amplitude=0.1, duration=.5, 880.)
-  metadata.map(insert_missing=true, fun (_) -> [("source", "s2")], s)
+  metadata.map(
+    insert_missing=true, fun (_) -> [("source", "s2")], s
+  )
 end

 s = append(merge=true, music, next)
diff --git a/tests/regression/seek_track_map.liq b/tests/regression/seek_track_map.liq
index cfbd457..3e5c3e2 100644
--- a/tests/regression/seek_track_map.liq
+++ b/tests/regression/seek_track_map.liq
@@ -8,7 +8,7 @@ def set_cues(s) =
     [("liq_cue_in", "#{in}"), ("liq_cue_out", "#{out}")]
   end

-  metadata.map(f, s)
+  metadata.map(insert_missing=true, f, s)
 end

 s = set_cues(s)
diff --git a/tests/streams/cross-override-end.liq b/tests/streams/cross-override-end.liq
index 04b1108..98c97a9 100644
--- a/tests/streams/cross-override-end.liq
+++ b/tests/streams/cross-override-end.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_end_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(end_duration=5., start_duration=4., s)
diff --git a/tests/streams/cross-override-start.liq b/tests/streams/cross-override-start.liq
index 22db72c..6a7d1f8 100644
--- a/tests/streams/cross-override-start.liq
+++ b/tests/streams/cross-override-start.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_start_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(start_duration=5., end_duration=4., s)
diff --git a/tests/streams/cross-override.liq b/tests/streams/cross-override.liq
index 7446fc0..be81360 100644
--- a/tests/streams/cross-override.liq
+++ b/tests/streams/cross-override.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(duration=5., s)
diff --git a/tests/streams/cross-persist-end-override.liq b/tests/streams/cross-persist-end-override.liq
index c6ef962..f5c2c5a 100644
--- a/tests/streams/cross-persist-end-override.liq
+++ b/tests/streams/cross-persist-end-override.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_end_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(persist_override=true, start_duration=5., end_duration=4., s)
diff --git a/tests/streams/cross-persist-override.liq b/tests/streams/cross-persist-override.liq
index 05eb631..817157d 100644
--- a/tests/streams/cross-persist-override.liq
+++ b/tests/streams/cross-persist-override.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(persist_override=true, duration=5., s)
diff --git a/tests/streams/cross-persist-start-override.liq b/tests/streams/cross-persist-start-override.liq
index bf3e85d..d3854aa 100644
--- a/tests/streams/cross-persist-start-override.liq
+++ b/tests/streams/cross-persist-start-override.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(id="a", update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, id="a", update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     id="b",
     update=false,
     (fun (_) -> [("source", "b"), ("liq_cross_start_duration", "1.1")]),
@@ -13,7 +17,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(id="c", update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, id="c", update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])
 s = crossfade(persist_override=true, start_duration=5., end_duration=4., s)
diff --git a/tests/streams/cross.liq b/tests/streams/cross.liq
index f96f3ce..bf5be70 100644
--- a/tests/streams/cross.liq
+++ b/tests/streams/cross.liq
@@ -1,8 +1,14 @@
 video.frame.rate.set(24)
 a = sine(duration=5., 440.)
-a = metadata.map(update=false, (fun (_) -> [("title", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "a")]), a
+  )
 b = sine(duration=5., 880.)
-b = metadata.map(update=false, (fun (_) -> [("title", "b")]), b)
+b =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "b")]), b
+  )
 s = sequence([a, b])

 def t(a, b) =
diff --git a/tests/streams/crossfade-plot.liq b/tests/streams/crossfade-plot.liq
index dd8c92f..3aebbdc 100644
--- a/tests/streams/crossfade-plot.liq
+++ b/tests/streams/crossfade-plot.liq
@@ -3,6 +3,7 @@ log.level := 5
 a = sine(duration=20., 440.)
 a =
   metadata.map(
+    insert_missing=true,
     update=false,
     fun (_) ->
       [
@@ -18,6 +19,7 @@ a =
 b = sine(duration=20., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     update=false,
     fun (_) ->
       [
diff --git a/tests/streams/crossfade.liq b/tests/streams/crossfade.liq
index cd195d3..d6df92f 100644
--- a/tests/streams/crossfade.liq
+++ b/tests/streams/crossfade.liq
@@ -1,10 +1,16 @@
 video.frame.rate.set(24)

 a = sine(duration=20., 440.)
-a = metadata.map(update=false, (fun (_) -> [("title", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "a")]), a
+  )

 b = sine(duration=20., 880.)
-b = metadata.map(update=false, (fun (_) -> [("title", "b")]), b)
+b =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("title", "b")]), b
+  )

 s = sequence([a, b])

diff --git a/tests/streams/fades-overrides.liq b/tests/streams/fades-overrides.liq
index a5cd276..07e3db2 100644
--- a/tests/streams/fades-overrides.liq
+++ b/tests/streams/fades-overrides.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     update=false,
     (
       fun (_) ->
@@ -21,7 +25,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])

diff --git a/tests/streams/fades-persistent-override.liq b/tests/streams/fades-persistent-override.liq
index a24d76a..a3666b1 100644
--- a/tests/streams/fades-persistent-override.liq
+++ b/tests/streams/fades-persistent-override.liq
@@ -1,11 +1,15 @@
 success = ref(false)

 a = sine(duration=5., 440.)
-a = metadata.map(update=false, (fun (_) -> [("source", "a")]), a)
+a =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("source", "a")]), a
+  )

 b = sine(duration=5., 880.)
 b =
   metadata.map(
+    insert_missing=true,
     update=false,
     (
       fun (_) ->
@@ -21,7 +25,10 @@ b =
   )

 c = sine(duration=5., 440.)
-c = metadata.map(update=false, (fun (_) -> [("source", "c")]), c)
+c =
+  metadata.map(
+    insert_missing=true, update=false, (fun (_) -> [("source", "c")]), c
+  )

 s = sequence([a, b, c])

diff --git a/tests/streams/hls_id3v2.liq b/tests/streams/hls_id3v2.liq
index a48e38c..03bc357 100644
--- a/tests/streams/hls_id3v2.liq
+++ b/tests/streams/hls_id3v2.liq
@@ -167,6 +167,7 @@ end
 s = sine()
 s =
   metadata.map(
+    insert_missing=true,
     fun (_) ->
       [
         (
diff --git a/tests/streams/random.liq b/tests/streams/random.liq
index b85a99c..d55959a 100644
--- a/tests/streams/random.liq
+++ b/tests/streams/random.liq
@@ -9,7 +9,7 @@ def m1(_) =
   [("id", "s1")]
 end

-s1 = metadata.map(id="s1-map", m1, s1)
+s1 = metadata.map(insert_missing=true, id="s1-map", m1, s1)
 s1_ready = ref(true)
 s1 = switch(id="s1", track_sensitive=false, [(s1_ready, s1)])
 s1_weight = ref(1)
@@ -19,7 +19,7 @@ def m2(_) =
   [("id", "s2")]
 end

-s2 = metadata.map(id="s2-map", m2, s2)
+s2 = metadata.map(insert_missing=true, id="s2-map", m2, s2)
 s2_ready = ref(false)
 s2 = switch(id="s2", track_sensitive=false, [(s2_ready, s2)])
 s2_weight = ref(1)
diff --git a/tests/streams/rotate.liq b/tests/streams/rotate.liq
index 1c6c845..804f728 100644
--- a/tests/streams/rotate.liq
+++ b/tests/streams/rotate.liq
@@ -1,5 +1,10 @@
 def mksource(id="", url) =
-  metadata.map(id=id, fun (_) -> [("source", id)], mksafe(playlist(url)))
+  metadata.map(
+    insert_missing=true,
+    id=id,
+    fun (_) -> [("source", id)],
+    mksafe(playlist(url))
+  )
 end

 jingles = mksource("jingles", "jingles")