diff --git a/lib/audioconv.js b/lib/audioconv.js
index f17467c..1b771f1 100644
--- a/lib/audioconv.js
+++ b/lib/audioconv.js
@@ -39,7 +39,8 @@ const {
   createDirIfNotExistSync,
   createLogFile,
   dropNullAndUndefined,
-  isNullOrUndefined
+  isNullOrUndefined,
+  isObject
 } = require('./utils');
 
 /**
@@ -193,7 +194,9 @@ function splitOptions(options) {
  * @return {module:audioconv~ResolvedConvertAudioOptions} The resolved options.
  * @since  1.0.0
  */
-function resolveOptions(options, useDefault=true) {
+function resolveOptions(options, useDefault=false) {
+  if (!isObject(options)) return defaultOptions;
+
   return {
     inputOptions: (
       Array.isArray(options?.inputOptions)
@@ -457,12 +460,18 @@ async function convertAudio(inFile, options = defaultOptions) {
           || (Array.isArray(options.outputOptions) && options.outputOptions.length === 0)
       )
     ) {
-      ffmpegChain
-        .audioBitrate(options.bitrate)
-        .audioCodec(options.codec)
-        .audioChannels(options.channels)
-        .audioFrequency(options.frequency)
-        .outputFormat(options.format);
+      // Add each option only if present and specified
+      // By using this logic, now user can convert an audio file with only specifying
+      // the output audio format
+      if (options.bitrate) ffmpegChain.audioBitrate(options.bitrate);
+      if (options.codec) ffmpegChain.audioCodec(options.codec);
+      if (options.channels) ffmpegChain.audioChannels(options.channels);
+      if (options.frequency) ffmpegChain.audioFrequency(options.frequency);
+
+      // Mandatory for output format
+      // Note: Specifying the same output format as input may copy the input file
+      //       with the same codec and format
+      ffmpegChain.outputFormat(options.format);
     } else {
       if (Array.isArray(options.inputOptions)) {
         ffmpegChain.inputOptions(options.inputOptions);
diff --git a/test/unittest/audioconv.spec.mjs b/test/unittest/audioconv.spec.mjs
index 5ab8624..fd53604 100644
--- a/test/unittest/audioconv.spec.mjs
+++ b/test/unittest/audioconv.spec.mjs
@@ -12,7 +12,7 @@ describe('module:audioconv', function () {
     ],
     resolveOptions: [
       'should return default options if given argument is nullable value',
-      'should return nullable options if given argument is nullable value',
+      'should return default options if given argument is not an object',
       'should resolve the given configuration options'
     ]
   };
@@ -92,7 +92,7 @@ describe('module:audioconv', function () {
     });
 
     it(testMessages.resolveOptions[0], function () {
-      const actualOptions = [null, undefined, {}].map((val) => {
+      const actualOptions = [null, undefined, false].map((val) => {
         return audioconv.resolveOptions(val , true);
       });
 
@@ -110,15 +110,16 @@ describe('module:audioconv', function () {
     });
 
     it(testMessages.resolveOptions[1], function () {
-      const actualOptions = [null, undefined, {}].map((val) => {
+      const actualOptions = ['&', /y/, 16n].map((val) => {
         return audioconv.resolveOptions(val , false);
       });
 
       actualOptions.forEach((actual) => {
         assert.notStrictEqual(actual, null);  // Non-nullable
         assert.notStrictEqual(typeof actual, 'undefined');
-        assert.notDeepStrictEqual(actual, expectedOptions[0]);
-        assert.deepStrictEqual(actual, expectedOptions[2]);
+        assert.deepStrictEqual(actual, expectedOptions[0]);
+        assert.notDeepStrictEqual(actual, expectedOptions[1]);
+        assert.notDeepStrictEqual(actual, expectedOptions[2]);
       });
       [...actualOptions].reverse().forEach((actual1) => {
         actualOptions.forEach((actual2) => {