MediaCodec: Decoding AAC android

Encoding/Decoding for various audio/video formats is now possible in android since
JellyBean. Sample code below shows AAC decoding using MediaCodec API provided in
android JellyBean and above.

Sample InputFile
Sample input file, songwav.mp4 is also created using MediaCodec and MediaMuxer.
Songwav.mp4 file AAC encoded file with following parameters:

    MediaFormat outputFormat = MediaFormat.createAudioFormat(
            "audio/mp4a-latm", 44100, 2);
    outputFormat.setInteger(MediaFormat.KEY_AAC_PROFILE,
            MediaCodecInfo.CodecProfileLevel.AACObjectLC);
    outputFormat.setInteger(MediaFormat.KEY_BIT_RATE,
            128000);

AAC Decoding
AAC file is decoded using MediaExtractor and MediaCodec. AudioTrack is used to play
the audio while decoding.

String inputfilePath = Environment.getExternalStorageDirectory()
            .getPath() + "/" + "songwav.mp4";
String outputFilePath = Environment.getExternalStorageDirectory()
            .getPath() + "/" + "songwavmp4.pcm";
OutputStream outputStream = new FileOutputStream(outputFilePath);
    MediaCodec codec;
    AudioTrack audioTrack;

// extractor gets information about the stream
MediaExtractor extractor = new MediaExtractor();
extractor.setDataSource(inputfilePath);

        MediaFormat format = extractor.getTrackFormat(0);
    String mime = format.getString(MediaFormat.KEY_MIME);

    // the actual decoder
    codec = MediaCodec.createDecoderByType(mime);
    codec.configure(format, null /* surface */, null /* crypto */, 0 /* flags */);
    codec.start();
    ByteBuffer[] codecInputBuffers = codec.getInputBuffers();
    ByteBuffer[] codecOutputBuffers = codec.getOutputBuffers();

    // get the sample rate to configure AudioTrack
    int sampleRate = format.getInteger(MediaFormat.KEY_SAMPLE_RATE);

    // create our AudioTrack instance
    audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, sampleRate,
            AudioFormat.CHANNEL_OUT_STEREO, AudioFormat.ENCODING_PCM_16BIT,
            AudioTrack.getMinBufferSize(sampleRate,
                    AudioFormat.CHANNEL_OUT_STEREO,
                    AudioFormat.ENCODING_PCM_16BIT), AudioTrack.MODE_STREAM);

    // start playing, we will feed you later
    audioTrack.play();
    extractor.selectTrack(0);

    // start decoding
    final long kTimeOutUs = 10000;
    MediaCodec.BufferInfo BufInfo = new MediaCodec.BufferInfo();
    boolean sawInputEOS = false;
    boolean sawOutputEOS = false;

    int inputBufIndex;

    int counter=0;
while (!sawOutputEOS) {


        counter++;
        if (!sawInputEOS) {
            inputBufIndex = codec.dequeueInputBuffer(kTimeOutUs);
            // Log.d(LOG_TAG, " bufIndexCheck " + bufIndexCheck);
            if (inputBufIndex >= 0) {
                ByteBuffer dstBuf = codecInputBuffers[inputBufIndex];

                int sampleSize = extractor
                        .readSampleData(dstBuf, 0 /* offset */);

                long presentationTimeUs = 0;

                if (sampleSize < 0) {

                    sawInputEOS = true;
                    sampleSize = 0;
                } else {

                    presentationTimeUs = extractor.getSampleTime();
                }
                // can throw illegal state exception (???)

                codec.queueInputBuffer(inputBufIndex, 0 /* offset */,
                        sampleSize, presentationTimeUs,
                        sawInputEOS ? MediaCodec.BUFFER_FLAG_END_OF_STREAM
                                : 0);

                if (!sawInputEOS) {
                    extractor.advance();
                }
            } else {
                Log.e("sohail", "inputBufIndex " + inputBufIndex);
            }
        }

        int res = codec.dequeueOutputBuffer(BufInfo, kTimeOutUs);

        if (res >= 0) {
            Log.i("sohail","decoding: deqOutputBuffer >=0, counter="+counter);
            // Log.d(LOG_TAG, "got frame, size " + info.size + "/" +
            // info.presentationTimeUs);
            if (BufInfo.size > 0) {
                // noOutputCounter = 0;
            }

            int outputBufIndex = res;
            ByteBuffer buf = codecOutputBuffers[outputBufIndex];

            final byte[] chunk = new byte[BufInfo.size];
            buf.get(chunk);
            buf.clear();

            if (chunk.length > 0) {
                // play
                audioTrack.write(chunk, 0, chunk.length);
                // write to file
                outputStream.write(chunk);

            }
            codec.releaseOutputBuffer(outputBufIndex, false /* render */);
            if ((BufInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                Log.i("sohail", "saw output EOS.");
                sawOutputEOS = true;
            }
        } else if (res == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
            codecOutputBuffers = codec.getOutputBuffers();

            Log.i("sohail", "output buffers have changed.");
        } else if (res == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
            MediaFormat oformat = codec.getOutputFormat();

            Log.i("sohail", "output format has changed to " + oformat);
        } else {
            Log.i("sohail", "dequeueOutputBuffer returned " + res);
        }
    }

    Log.d(LOG_TAG, "stopping...");

    // ////////closing
    if (audioTrack != null) {
        audioTrack.flush();
        audioTrack.release();
        audioTrack = null;
    }

    outputStream.flush();
    outputStream.close();

    codec.stop();