Allow customizing framerate of the color source

Author: pedromsilvapt

package.json

@@ -1,6 +1,6 @@
 {
   "name": "composable",
-  "version": "0.9.3",
+  "version": "0.9.4",
   "description": "Easily compose complex and reusable ffmpeg filters using JavaScript functions and generate the command string on the fly",
   "main": "./lib/main.js",
   "types": "./lib/main.d.ts",

src/Filters/Sources/Color.ts

@@ -36,10 +36,10 @@ export class ColorSourceFilter extends NativeFilter {
     parameters : string[] = [ 'color', 'size', 'rate' ]
 }
 
-export function color ( color : string, width : number, height : number, duration : number = null ) : OutputStream {
+export function color ( color : string, width : number, height : number, duration : number = null, rate : string | number = null ) : OutputStream {
     return new ColorSourceFilter( [ color ], {
         size: '' + width + 'x' + height,
-        rate: '24000/1001',
+        rate: rate,
         duration: duration
     } ).outputs[ 0 ];
 }