Android MediaCodec Encode and Decode In Asynchronous Mode

Question

I am trying to decode a video from a file and encode it into a different format with MediaCodec in the new Asynchronous Mode supported in API Level 21 and up (Android OS 5.0 Lollipop).

There are many examples for doing this in Synchronous Mode on sites such as Big Flake, Google's Grafika, and dozens of answers on StackOverflow, but none of them support Asynchronous mode.

I do not need to display the video during the process.

I believe that the general procedure is to read the file with a MediaExtractor as the input to a MediaCodec(decoder), allow the output of the Decoder to render into a Surface that is also the shared input into a MediaCodec(encoder), and then finally to write the Encoder output file via a MediaMuxer. The Surface is created during setup of the Encoder and shared with the Decoder.

I can Decode the video into a TextureView, but sharing the Surface with the Encoder instead of the screen has not been successful.

I setup MediaCodec.Callback()s for both of my codecs. I believe that an issues is that I do not know what to do in the Encoder's callback's onInputBufferAvailable() function. I do not what to (or know how to) copy data from the Surface into the Encoder - that should happen automatically (as is done on the Decoder output with codec.releaseOutputBuffer(outputBufferId, true);). Yet, I believe that onInputBufferAvailable requires a call to codec.queueInputBuffer in order to function. I just don't know how to set the parameters without getting data from something like a MediaExtractor as used on the Decode side.

If you have an Example that opens up a video file, decodes it, encodes it to a different resolution or format using the asynchronous MediaCodec callbacks, and then saves it as a file, please share your sample code.

=== EDIT ===

Here is a working example in synchronous mode of what I am trying to do in asynchronous mode: ExtractDecodeEditEncodeMuxTest.java: https://android.googlesource.com/platform/cts/+/jb-mr2-release/tests/tests/media/src/android/media/cts/ExtractDecodeEditEncodeMuxTest.java This example is working in my application

user_8270308 · Answer

Can also set the Handler in the MediaEncoder.

---> AudioEncoderCallback(aacSamplePreFrameSize),mHandler);

MyAudioCodecWrapper myMediaCodecWrapper;

public MyAudioEncoder(long startRecordWhenNs){
    super.startRecordWhenNs = startRecordWhenNs;
}

@RequiresApi(api = Build.VERSION_CODES.M)
public MyAudioCodecWrapper prepareAudioEncoder(AudioRecord _audioRecord , int aacSamplePreFrameSize)  throws Exception{
    if(_audioRecord==null || aacSamplePreFrameSize<=0)
        throw new Exception();

    audioRecord = _audioRecord;
    Log.d(TAG, "audioRecord:" + audioRecord.getAudioFormat() + ",aacSamplePreFrameSize:" + aacSamplePreFrameSize);

    mHandlerThread.start();
    mHandler = new Handler(mHandlerThread.getLooper());

    MediaFormat audioFormat = new MediaFormat();
    audioFormat.setString(MediaFormat.KEY_MIME, MIMETYPE_AUDIO_AAC);
    //audioFormat.setInteger(MediaFormat.KEY_BIT_RATE, BIT_RATE );
    audioFormat.setInteger(MediaFormat.KEY_AAC_PROFILE, MediaCodecInfo.CodecProfileLevel.AACObjectLC);
    audioFormat.setInteger(MediaFormat.KEY_SAMPLE_RATE, audioRecord.getSampleRate());//44100
    audioFormat.setInteger(MediaFormat.KEY_CHANNEL_COUNT, audioRecord.getChannelCount());//1(單身道)
    audioFormat.setInteger(MediaFormat.KEY_BIT_RATE, 128000);
    audioFormat.setInteger(MediaFormat.KEY_MAX_INPUT_SIZE, 16384);
    MediaCodec codec = MediaCodec.createEncoderByType(MIMETYPE_AUDIO_AAC);
    codec.configure(audioFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
    codec.setCallback(new AudioEncoderCallback(aacSamplePreFrameSize),mHandler);
    //codec.start();

    MyAudioCodecWrapper myMediaCodecWrapper = new MyAudioCodecWrapper();
    myMediaCodecWrapper.mediaCodec = codec;

    super.mediaCodec = codec;

    return myMediaCodecWrapper;

}

Android MediaCodec Encode and Decode In Asynchronous Mode

2 Answers