fix audio only filters

src/stores.js

@@ -109,9 +109,11 @@ export const previewCommand = derived([edges, nodes], ([$edges, $nodes]) => {
       finalCommand.push("0:a");
     }
 
-    if (hasVid) {
 		finalCommand.push("-map");
+    if (hasVid) {
       finalCommand.push('"[vid_out]"');
+    } else {
+      finalCommand.push("0:v");
     }
   }
 
@@ -253,6 +255,12 @@ export function addNode(_data, type) {
   });
 }
 
+export function resetNodes() {
+	nodes.set([]);
+	addNode({ name: "punch.mp4" }, "input");
+	addNode({ name: "out.mp4" }, "output");
+}
+
 export function removeNode(id) {
   nodes.update((_nodes) => {
     const index = _nodes.findIndex((n) => n.id === id);

tests/unit-tests/commandbuilder.js

@@ -1,5 +1,6 @@
 import { expect, test, describe } from "vitest";
-import { makeFilterArgs } from "../../src/stores.js";
+import { get } from "svelte/store";
+import { nodes, edges, addNode, resetNodes, makeFilterArgs, previewCommand } from "../../src/stores.js";
 
 describe("Filter param builder", () => {
 	test("No params", () => {
@@ -38,7 +39,7 @@ describe("Filter param builder", () => {
 			name: "filter",
 			params: [
 				{ name: "param1", value: 1, default: 1 }, // should be ignored
-				{ name: "param2", value: "", }, // should be ignored
+				{ name: "param2", value: "" }, // should be ignored
 				{ name: "param3", value: 1, default: 2 },
 				{ name: "param4", value: 2 },
 				{ name: "param5", value: "p5" },
@@ -47,3 +48,25 @@ describe("Filter param builder", () => {
 		expect(results).toBe("filter=param3=1:param4=2:param5=p5");
 	});
 });
+
+describe("Command builder", () => {
+	test("Defaults", () => {
+		expect(get(previewCommand)).toBe("ffmpeg -i punch.mp4 out.mp4");
+	});
+
+	test("Simple video filter", () => {
+		resetNodes();
+		addNode({ name: "filter", type: "V->V" }, "filter");
+		expect(get(previewCommand)).toBe(
+			`ffmpeg -i punch.mp4 -filter_complex "[0:v]filter[vid_out]" -map 0:a -map "[vid_out]" out.mp4`
+		);
+	});
+
+	test("Simple audio filter", () => {
+		resetNodes();
+		addNode({ name: "filter", type: "A->A" }, "filter");
+		expect(get(previewCommand)).toBe(
+			`ffmpeg -i punch.mp4 -filter_complex "[0:a]filter[aud_out]" -map "[aud_out]" -map 0:v out.mp4`
+		);
+	});
+});