Fix external encoder. Fixes: #3020

.ocamlformat

@@ -1,4 +1,4 @@
-version=0.24.1
+version=0.25.1
 profile = conventional
 break-separators = after
 space-around-lists = false

CHANGES.md

@@ -3,6 +3,7 @@
 
 Fixed:
 * Fixed non-monotonous PTS in ffmpeg raw content (#2978)
+* Fixed external encoder (#3020)
 
 2.1.4 (2022-03-01)
 =====

src/encoder/external_encoder.ml

@@ -112,13 +112,13 @@ let encoder id ext =
   let encode frame start len =
     let channels = ext.channels in
     let samplerate = Lazy.force ext.samplerate in
-    let width, height = Option.get ext.video in
-    let width = Lazy.force width in
-    let height = Lazy.force height in
     let sbuf =
-      if ext.video <> None then
+      if ext.video <> None then (
+        let width, height = Option.get ext.video in
+        let width = Lazy.force width in
+        let height = Lazy.force height in
         Avi_encoder.encode_frame ~channels ~samplerate ~converter ~width ~height
-          frame start len
+          frame start len)
       else (
         let b = AFrame.pcm frame in
         let start = Frame.audio_of_main start in

tests/regression/external-encoder.liq

@@ -0,0 +1,13 @@
+s = sine()
+
+tmp = file.temp("foo", "flv")
+on_shutdown({file.remove(tmp)})
+
+encoder = %external(process="cat")
+
+output.file(
+  encoder,
+  "/tmp/cat",
+  on_start=test.pass,
+  sine()
+)