add super equalizer of audio effect

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

@@ -119,6 +119,7 @@ class AudioHandleActivity : BaseActivity() {
                 R.id.btn_audio_echo,
                 R.id.btn_audio_tremolo,
                 R.id.btn_audio_denoise,
+                R.id.btn_audio_equalizer,
                 R.id.btn_audio_silence,
                 R.id.btn_audio_volume
         )
@@ -256,6 +257,19 @@ class AudioHandleActivity : BaseActivity() {
                 val noisePath = PATH + File.separator + "denoise.mp3"
                 commandLine = FFmpegUtil.audioDenoise(srcFile, noisePath)
             }
+            R.id.btn_audio_equalizer // equalizer plus
+            -> {
+                // key:band  value:gain=[0-20]
+                val bandList = arrayListOf<String>()
+                bandList.add("6b=5")
+                bandList.add("8b=4")
+                bandList.add("10b=3")
+                bandList.add("12b=2")
+                bandList.add("14b=1")
+                bandList.add("16b=0")
+                val equalizePath = PATH + File.separator + "equalize.mp3"
+                commandLine = FFmpegUtil.audioEqualizer(srcFile, bandList, equalizePath)
+            }
             R.id.btn_audio_silence //silence detect
             -> {
                 commandLine = FFmpegUtil.audioSilenceDetect(srcFile)

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

@@ -160,6 +160,32 @@ public class FFmpegUtil {
         return volumeCmd.split(" ");
     }
 
+    /**
+     * Apply 18 band of equalizer into audio
+     *
+     * @param inputPath  input file
+     * @param bandList   bandList
+     * @param outputPath output file
+     */
+    public static String[] audioEqualizer(String inputPath, List<String> bandList, String outputPath) {
+        // unit: Hz  gain:0-20
+        /*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+         |   1b   |   2b   |   3b   |   4b   |   5b   |   6b   |   7b   |   8b   |   9b   |
+         |   65   |   92   |   131  |   185  |   262  |   370  |   523  |   740  |  1047  |
+         |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+         |   10b  |   11b  |   12b  |   13b  |   14b  |   15b  |   16b  |   17b  |   18b  |
+         |   1480 |   2093 |   2960 |   4186 |   5920 |   8372 |  11840 |  16744 |  20000 |
+         |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -*/
+        StringBuilder builder = new StringBuilder();
+        for (String band:bandList) {
+            builder.append(band).append(":");
+        }
+        builder.deleteCharAt(builder.length()-1);
+        String equalizerCmd = "ffmpeg -i %s -af superequalizer=%s -y %s";
+        equalizerCmd = String.format(Locale.getDefault(), equalizerCmd, inputPath, builder.toString(), outputPath);
+        return equalizerCmd.split(" ");
+    }
+
     /**
      * mux audio and video together
      *

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

@@ -16,7 +16,7 @@
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
             android:text="@string/audio_transform"
-            android:layout_marginTop="40dp" />
+            android:layout_marginTop="10dp" />
 
         <Button
             android:id="@+id/btn_cut"
@@ -99,6 +99,13 @@
             android:text="@string/audio_denoise"
             android:layout_marginTop="10dp" />
 
+        <Button
+            android:id="@+id/btn_audio_equalizer"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/audio_add_equalizer"
+            android:layout_marginTop="10dp" />
+
         <Button
             android:id="@+id/btn_audio_silence"
             android:layout_width="wrap_content"

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

@@ -2,7 +2,7 @@
     <string name="app_name">FFmpegAndroid</string>
     <string name="audio_transform">音频转码</string>
     <string name="audio_cut">音频剪切</string>
-    <string name="audio_concat">音频合并</string>
+    <string name="audio_concat">音频拼接</string>
     <string name="audio_mix">音乐混音</string>
     <string name="audio_play">音频解码AudioTrack播放</string>
     <string name="audio_opensl">音频解码OpenSL播放</string>