Add public interface for audio transcoding

Author: ypresto

README.md

@@ -48,7 +48,7 @@ protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         }
     };
     MediaTranscoder.getInstance().transcodeVideo(fileDescriptor, file.getAbsolutePath(),
-            MediaFormatStrategyPresets.createAndroid720pStrategy(), listener); // or createAndroid720pStrategy([your bit rate here])
+            MediaFormatStrategyPresets.createAndroid720pStrategy(), listener); // or createAndroid720pStrategy([your bitrate here])
 }
 ```
 

example/src/main/java/net/ypresto/androidtranscoder/example/TranscoderActivity.java

@@ -104,7 +104,7 @@ public void onTranscodeFailed(Exception exception) {
                     };
                     Log.d(TAG, "transcoding into " + file);
                     mFuture = MediaTranscoder.getInstance().transcodeVideo(fileDescriptor, file.getAbsolutePath(),
-                            MediaFormatStrategyPresets.createAndroid720pStrategy(), listener);
+                            MediaFormatStrategyPresets.createAndroid720pStrategy(8000 * 1000, 128 * 1000, 1), listener);
                     switchButtonEnabled(true);
                 }
                 break;

lib/src/main/java/net/ypresto/androidtranscoder/format/Android16By9FormatStrategy.java

@@ -20,6 +20,8 @@
 import android.util.Log;
 
 class Android16By9FormatStrategy implements MediaFormatStrategy {
+    public static final int AUDIO_BITRATE_AS_IS = -1;
+    public static final int AUDIO_CHANNELS_AS_IS = -1;
     public static final int SCALE_720P = 5;
     private static final String TAG = "Android16By9FormatStrategy";
     private final int mScale;
@@ -28,7 +30,7 @@ class Android16By9FormatStrategy implements MediaFormatStrategy {
     private final int mAudioChannels;
 
     public Android16By9FormatStrategy(int scale, int videoBitrate) {
-        this(scale, videoBitrate, 0, 0);
+        this(scale, videoBitrate, AUDIO_BITRATE_AS_IS, AUDIO_CHANNELS_AS_IS);
     }
 
     public Android16By9FormatStrategy(int scale, int videoBitrate, int audioBitrate, int audioChannels) {
@@ -74,7 +76,7 @@ public MediaFormat createVideoOutputFormat(MediaFormat inputFormat) {
 
     @Override
     public MediaFormat createAudioOutputFormat(MediaFormat inputFormat) {
-        if (mAudioBitrate == 0 || mAudioChannels == 0) return null;
+        if (mAudioBitrate == AUDIO_BITRATE_AS_IS || mAudioChannels == AUDIO_CHANNELS_AS_IS) return null;
 
         // Use original sample rate, as resampling is not supported yet.
         final MediaFormat format = MediaFormat.createAudioFormat(MediaFormatExtraConstants.MIMETYPE_AUDIO_AAC,

lib/src/main/java/net/ypresto/androidtranscoder/format/Android720pFormatStrategy.java

@@ -20,24 +20,26 @@
 import android.util.Log;
 
 class Android720pFormatStrategy implements MediaFormatStrategy {
+    public static final int AUDIO_BITRATE_AS_IS = -1;
+    public static final int AUDIO_CHANNELS_AS_IS = -1;
     private static final String TAG = "720pFormatStrategy";
     private static final int LONGER_LENGTH = 1280;
     private static final int SHORTER_LENGTH = 720;
-    private static final int DEFAULT_BITRATE = 8000 * 1000; // From Nexus 4 Camera in 720p
-    private final int mVideoBitRate;
+    private static final int DEFAULT_VIDEO_BITRATE = 8000 * 1000; // From Nexus 4 Camera in 720p
+    private final int mVideoBitrate;
     private final int mAudioBitrate;
     private final int mAudioChannels;
 
     public Android720pFormatStrategy() {
-        this(DEFAULT_BITRATE, 0, 0);
+        this(DEFAULT_VIDEO_BITRATE);
     }
 
     public Android720pFormatStrategy(int videoBitrate) {
-        this(videoBitrate, 0, 0);
+        this(videoBitrate, AUDIO_BITRATE_AS_IS, AUDIO_CHANNELS_AS_IS);
     }
 
     public Android720pFormatStrategy(int videoBitrate, int audioBitrate, int audioChannels) {
-        mVideoBitRate = videoBitrate;
+        mVideoBitrate = videoBitrate;
         mAudioBitrate = audioBitrate;
         mAudioChannels = audioChannels;
     }
@@ -67,7 +69,7 @@ public MediaFormat createVideoOutputFormat(MediaFormat inputFormat) {
         }
         MediaFormat format = MediaFormat.createVideoFormat("video/avc", outWidth, outHeight);
         // From Nexus 4 Camera in 720p
-        format.setInteger(MediaFormat.KEY_BIT_RATE, mVideoBitRate);
+        format.setInteger(MediaFormat.KEY_BIT_RATE, mVideoBitrate);
         format.setInteger(MediaFormat.KEY_FRAME_RATE, 30);
         format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 3);
         format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);
@@ -76,7 +78,7 @@ public MediaFormat createVideoOutputFormat(MediaFormat inputFormat) {
 
     @Override
     public MediaFormat createAudioOutputFormat(MediaFormat inputFormat) {
-        if (mAudioBitrate == 0 || mAudioChannels == 0) return null;
+        if (mAudioBitrate == AUDIO_BITRATE_AS_IS || mAudioChannels == AUDIO_CHANNELS_AS_IS) return null;
 
         // Use original sample rate, as resampling is not supported yet.
         final MediaFormat format = MediaFormat.createAudioFormat(MediaFormatExtraConstants.MIMETYPE_AUDIO_AAC,

lib/src/main/java/net/ypresto/androidtranscoder/format/MediaFormatStrategyPresets.java

@@ -34,11 +34,26 @@ public static MediaFormatStrategy createAndroid720pStrategy() {
     /**
      * Preset based on Nexus 4 camera recording with 720p quality.
      * This preset is ensured to work on any Android >=4.3 devices by Android CTS (if codec is available).
+     * Audio track will be copied as-is.
      *
-     * @param bitRate Preferred bit rate for encoding.
+     * @param bitrate Preferred bitrate for video encoding.
      */
-    public static MediaFormatStrategy createAndroid720pStrategy(int bitRate) {
-        return new Android720pFormatStrategy(bitRate);
+    public static MediaFormatStrategy createAndroid720pStrategy(int bitrate) {
+        return new Android720pFormatStrategy(bitrate);
+    }
+
+    /**
+     * Preset based on Nexus 4 camera recording with 720p quality.
+     * This preset is ensured to work on any Android >=4.3 devices by Android CTS (if codec is available).
+     * <p/>
+     * Note: audio transcoding is experimental feature.
+     *
+     * @param bitrate       Preferred bitrate for video encoding.
+     * @param audioBitrate  Preferred bitrate for audio encoding.
+     * @param audioChannels Output audio channels.
+     */
+    public static MediaFormatStrategy createAndroid720pStrategy(int bitrate, int audioBitrate, int audioChannels) {
+        return new Android720pFormatStrategy(bitrate, audioBitrate, audioChannels);
     }
 
     /**