change audio speed

app/src/main/java/com/frank/ffmpeg/activity/AudioHandleActivity.java

@@ -108,7 +108,8 @@ public class AudioHandleActivity extends BaseActivity {
                 R.id.btn_play_audio,
                 R.id.btn_play_opensl,
                 R.id.btn_audio_encode,
-                R.id.btn_pcm_concat
+                R.id.btn_pcm_concat,
+                R.id.btn_audio_speed
         );
     }
 
@@ -208,6 +209,11 @@ public class AudioHandleActivity extends BaseActivity {
                 FileUtil.concatFile(srcPCM, appendPCM, concatPCM);
                 mHandler.obtainMessage(MSG_FINISH).sendToTarget();
                 return;
+            case R.id.btn_audio_speed://change audio speed
+                float speed = 2.0f;//from 0.5 to 2.0
+                String speedPath = PATH + File.separator + "speed.mp3";
+                commandLine = FFmpegUtil.changeAudioSpeed(srcFile, speedPath, speed);
+                break;
             default:
                 break;
         }

app/src/main/java/com/frank/ffmpeg/util/FFmpegUtil.java

@@ -520,6 +520,22 @@ public class FFmpegUtil {
         return speedCmd.split(" ");
     }
 
+    /**
+     * Changing the speed of playing, speed range at 0.5-2 in audio.
+     * @param inputFile the inputFile of normal speed
+     * @param outputFile the outputFile which you want to change speed
+     * @param speed speed of playing
+     * @return change speed success or not
+     */
+    public static String[] changeAudioSpeed(String inputFile, String outputFile, float speed) {
+        if (speed > 2 || speed < 0.5) {
+            throw new IllegalArgumentException("audio speed range is from 0.5 to 2");
+        }
+        String speedCmd = "ffmpeg -i %s -filter_complex atempo=%.2f %s";
+        speedCmd = String.format(Locale.getDefault(), speedCmd, inputFile, speed, outputFile);
+        return speedCmd.split(" ");
+    }
+
     /**
      * Rebuild the keyframe index of FLV, make it seekable
      * @param inputFile inputFile

app/src/main/res/layout/activity_audio_handle.xml

@@ -66,6 +66,14 @@
             android:layout_height="wrap_content"
             android:text="@string/pcm_concat"
             android:layout_marginTop="10dp" />
+
+        <Button
+            android:id="@+id/btn_audio_speed"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/audio_speed"
+            android:layout_marginTop="10dp" />
+
     </LinearLayout>
 
     <include

app/src/main/res/values-en/strings.xml

@@ -8,6 +8,7 @@
     <string name="audio_opensl">OpenSL play</string>
     <string name="audio_encode">Audio encode</string>
     <string name="pcm_concat">PCM concat</string>
+    <string name="audio_speed">Audio speed</string>
 
     <string name="audio_handle">Audio handle</string>
     <string name="media_handle">Media handle</string>

app/src/main/res/values/strings.xml

@@ -8,6 +8,7 @@
     <string name="audio_opensl">音频解码OpenSL播放</string>
     <string name="audio_encode">音频编码</string>
     <string name="pcm_concat">PCM合并</string>
+    <string name="audio_speed">音频速度</string>
 
     <string name="audio_handle">音频处理</string>
     <string name="media_handle">音视频处理</string>