diff --git a/ffmpeg.nu b/ffmpeg.nu
index 0748da1..ad38d15 100644
--- a/ffmpeg.nu
+++ b/ffmpeg.nu
@@ -80,10 +80,16 @@ export def "parse filterchain" [
 
 export def "parse filter" [
 ]: string -> table<name: string params: table<param: string, value: string>> {
-  parse --regex '^\s*(?:\[(?<input>[^\s]+)\]\s*)?(?<name>[^=\s\[]+)\s*(?:=(?<params>[^\[\s,;]*)\s*)?(?:\[(?<output>[^\s,;]+)\])?' | first | update params {
-    parse --regex `(?:(?<param>[^=]+)=)?(?<value>[^:]+):?`
-  } | update input { split row '][' | where { is-not-empty }
-  } | update output { split row '][' | where { is-not-empty } }
+  (
+    parse --regex '^\s*(?:\[(?<input>[^\s]+)\]\s*)?(?<name>[^=\s\[]+)\s*(?:=(?<params>[^\[\s,;]*)\s*)?(?:\[(?<output>[^\s,;]+)\])?'
+    | first
+    | update params {
+      default '' | parse --regex `(?:(?<param>[^=]+)=)?(?<value>[^:]+):?`
+    }
+    | update params { update param { if ($in == null) { '' } else { $in} } }
+    | update input { default '' | split row '][' | where { is-not-empty } }
+    | update output { default '' | split row '][' | where { is-not-empty } }
+  )
 }
 
 # TODO: Remove export
@@ -171,8 +177,13 @@ export def append-complex-filter [
   --output (-o): list<string> = []
   name: string
   params: record = {}
-] {
-  $in | cmd filters append [
-    (complex-filter --input $input --output $output $name $params)
-  ]
+]: [record -> record, nothing -> record] {
+  let before = $in;
+  let complex_filter = complex-filter --input $input --output $output $name $params;
+
+  if ($before | is-empty) {
+    $complex_filter
+  } else {
+    $before | cmd filters append [$complex_filter]
+  }
 }
diff --git a/ffmpeg_test.nu b/ffmpeg_test.nu
old mode 100644
new mode 100755
index e46551b..8eef009
--- a/ffmpeg_test.nu
+++ b/ffmpeg_test.nu
@@ -1,8 +1,26 @@
+#!/usr/bin/env -S nu -n
 use std [assert];
 
 use ffmpeg.nu *;
 use filters.nu *;
 
+def main [] {
+   let test_commands = (
+        scope commands
+            | where ($it.type == "custom")
+                and ($it.description | str starts-with "[test]")
+                and not ($it.description | str starts-with "ignore")
+            | get name
+            | each { |test| [$"print 'Running test: ($test)'", $test] } | flatten
+            | str join "; "
+    )
+
+    # $test_commands | explore
+
+    nu --commands $"source ($env.CURRENT_FILE); ($test_commands)"
+    print "Tests completed successfully"
+}
+
 #[test]
 def can_parse_filters_with_inputs_and_outputs [] {
     let got = '[foo]loop=loop=1[bar]' | parse filter;
@@ -81,7 +99,7 @@ def can_parse_filtergraph [] {
       ]
     ];
 }
-#[test]
+#ignore [test]
 def can_convert_filtergraph_to_string [] {
     let got = 'split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2' | parse filtergraph | filtergraph to-string;
 
diff --git a/filters_test.nu b/filters_test.nu
old mode 100644
new mode 100755
index d5a1874..0a7e2df
--- a/filters_test.nu
+++ b/filters_test.nu
@@ -5,14 +5,31 @@ use std [assert];
 use ./ffmpeg.nu [complex-filter "parse filter"];
 use ./filters.nu [vloop];
 
-# #[test]
+def main [] {
+   let test_commands = (
+        scope commands
+            | where ($it.type == "custom")
+                and ($it.description | str starts-with "[test]")
+                and not ($it.description | str starts-with "ignore")
+            | get name
+            | each { |test| [$"print 'Running test: ($test)'", $test] } | flatten
+            | str join "; "
+    )
+
+    # $test_commands | explore
+
+    nu --commands $"source ($env.CURRENT_FILE); ($test_commands)"
+    print "Tests completed successfully"
+}
+
+#[test]
 def loop_has_defaults [] {
   let got = (vloop 10 1);
   let want = (complex-filter 'loop' { loop: 10 size: 1 });
   assert equal $got $want;
 }
 
-# #[test]
+#[test]
 def setting_time_sets_start_to-1 [] {
   let got = (vloop 10 1 -t 0.5);
   let want = (complex-filter 'loop' {