MP4 video transcode using Android MediaCodec API, pure Java (not LGPL nor patent issue!). Supports API >= 18.
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Latest commit 012c3ab Aug 11, 2018


Hardware accelerated transcoder for Android, written in pure Java.


Android does not offer straight forward way to transcode video.

FFmpeg is the most famous solution for transcoding. But using FFmpeg binary on Android can cause GPL and/or patent issues. Also using native code for Android development can be troublesome because of cross-compiling, architecture compatibility, build time and binary size.

To transcode without any hassle written above, I created this library to provide hardware accelerated transcoding of H.264 (mp4) video without ffmpeg by using MediaCodec.


API Level 18 (Android 4.3, JELLY_BEAN_MR2) or later. If your app targets older Android, you should add below line to AndroidManifest.xml:

<!-- Only supports API >= 18 -->
<uses-sdk tools:overrideLibrary="net.ypresto.androidtranscoder" />

Please ensure checking Build.VERSION by your self.


protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    ParcelFileDescriptor parcelFileDescriptor = resolver.openFileDescriptor(data.getData(), "r");
    FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
    MediaTranscoder.Listener listener = new MediaTranscoder.Listener() {
        public void onTranscodeProgress(double progress) {

        public void onTranscodeCompleted() {
            startActivity(new Intent(Intent.ACTION_VIEW).setDataAndType(Uri.fromFile(file), "video/mp4"));

        public void onTranscodeFailed(Exception exception) {
    MediaTranscoder.getInstance().transcodeVideo(fileDescriptor, file.getAbsolutePath(),
            MediaFormatStrategyPresets.createAndroid720pStrategy(), listener); // or createAndroid720pStrategy([your bitrate here])

See in example directory for ready-made transcoder app.

Quick Setup


Available from JCenter, which is default repo of gradle script generated by recent android studio.

repositories {
compile 'net.ypresto.androidtranscoder:android-transcoder:0.2.0'


  • This library raises RuntimeExceptions (like IlleagalStateException) in various situations. Please catch it and provide alternate logics. I know this is bad design according to Effective Java; just is TODO.
  • Currently this library does not generate streaming-aware mp4 file. Use qtfaststart-java to place moov atom at beginning of file.
  • Android does not gurantees that all devices have bug-free codecs/accelerators for your codec parameters (especially, resolution). Refer supported media formats for parameters guaranteed by CTS.
  • This library does not support video files recorded by other device like digital cameras, iOS (mov files, including non-baseline profile h.264), etc.

More information about internals

There is a blog post about this library written in Japanese.

While it is Japanese, diagrams would be useful for understanding internals of this library.

References for Android Low-Level Media APIs


Copyright (C) 2014-2016 Yuya Tanaka

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
See the License for the specific language governing permissions and
limitations under the License.