equalizer - 简化实现代码

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

@@ -244,14 +244,9 @@ public class FFmpegUtil {
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-        StringBuilder builder = new StringBuilder();
-        for (String band:bandList) {
-            builder.append(band).append(":");
-        }
-        builder.deleteCharAt(builder.length() - 1);
-        // "ffmpeg -i %s -af superequalizer=%s -y %s"
+        String bands = String.join(":", bandList);
         String equalizerCmd = "ffmpeg -i -af superequalizer=%s -y";
-        equalizerCmd = String.format(Locale.getDefault(), equalizerCmd, builder.toString());
+        equalizerCmd = String.format(Locale.getDefault(), equalizerCmd, bands);
         return insert(equalizerCmd.split(" "), 2, inputPath, outputPath);
     }