Merge "BLE-MIDI: fix timestamps for sysex data" into rvc-dev am: 2682bcf618 am: ec1e4705f7 (e5545c3c) · Commits · e / os / android_frameworks_base

media/packages/BluetoothMidiService/src/com/android/bluetoothmidiservice/BluetoothPacketDecoder.java

+44 −36

Original line number	Original line	Diff line number	Diff line
	@@ -22,24 +22,41 @@ import android.util.Log;
	import java.io.IOException;		import java.io.IOException;

	/**		/**
	* This is an abstract base class that decodes a packet buffer and passes it to a		* This is an abstract base class that decodes a BLE-MIDI packet
	* {@link android.media.midi.MidiReceiver}		* buffer and passes it to a {@link android.media.midi.MidiReceiver}
	*/		*/
	public class BluetoothPacketDecoder extends PacketDecoder {		public class BluetoothPacketDecoder extends PacketDecoder {

	private static final String TAG = "BluetoothPacketDecoder";		private static final String TAG = "BluetoothPacketDecoder";

	private final byte[] mBuffer;		private final byte[] mBuffer;
			private int mBytesInBuffer;
	private MidiBtleTimeTracker mTimeTracker;		private MidiBtleTimeTracker mTimeTracker;

	private final int TIMESTAMP_MASK_HIGH = 0x1F80;		private int mLowTimestamp;
	private final int TIMESTAMP_MASK_LOW = 0x7F;		private long mNanoTimestamp;
	private final int HEADER_TIMESTAMP_MASK = 0x3F;
			private static final int TIMESTAMP_MASK_HIGH = 0x1F80; // top 7 bits
			private static final int TIMESTAMP_MASK_LOW = 0x7F; // bottom 7 bits
			private static final int HEADER_TIMESTAMP_MASK = 0x3F; // bottom 6 bits

	public BluetoothPacketDecoder(int maxPacketSize) {		public BluetoothPacketDecoder(int maxPacketSize) {
	mBuffer = new byte[maxPacketSize];		mBuffer = new byte[maxPacketSize];
	}		}

			private void flushOutput(MidiReceiver receiver) {
			if (mBytesInBuffer > 0) {
			try {
			receiver.send(mBuffer, 0, mBytesInBuffer, mNanoTimestamp);
			} catch (IOException e) {
			// ???
			}
			mBytesInBuffer = 0;
			}
			}

			// NOTE: this code allows running status across packets,
			// although the specification does not allow that.
	@Override		@Override
	public void decodePacket(byte[] buffer, MidiReceiver receiver) {		public void decodePacket(byte[] buffer, MidiReceiver receiver) {
	if (mTimeTracker == null) {		if (mTimeTracker == null) {
	@@ -47,14 +64,11 @@ public class BluetoothPacketDecoder extends PacketDecoder {
	}		}

	int length = buffer.length;		int length = buffer.length;

	// NOTE his code allows running status across packets,
	// although the specification does not allow that.

	if (length < 1) {		if (length < 1) {
	Log.e(TAG, "empty packet");		Log.e(TAG, "empty packet");
	return;		return;
	}		}

	byte header = buffer[0];		byte header = buffer[0];
	if ((header & 0xC0) != 0x80) {		if ((header & 0xC0) != 0x80) {
	Log.e(TAG, "packet does not start with header");		Log.e(TAG, "packet does not start with header");
	@@ -64,52 +78,46 @@ public class BluetoothPacketDecoder extends PacketDecoder {
	// shift bits 0 - 5 to bits 7 - 12		// shift bits 0 - 5 to bits 7 - 12
	int highTimestamp = (header & HEADER_TIMESTAMP_MASK) << 7;		int highTimestamp = (header & HEADER_TIMESTAMP_MASK) << 7;
	boolean lastWasTimestamp = false;		boolean lastWasTimestamp = false;
	int dataCount = 0;
	int previousLowTimestamp = 0;		int previousLowTimestamp = 0;
	long nanoTimestamp = 0;		int currentTimestamp = highTimestamp \| mLowTimestamp;
	int currentTimestamp = 0;

	// iterate through the rest of the packet, separating MIDI data from timestamps		// Iterate through the rest of the packet, separating MIDI data from timestamps.
	for (int i = 1; i < buffer.length; i++) {		for (int i = 1; i < buffer.length; i++) {
	byte b = buffer[i];		byte b = buffer[i];

			// Is this a timestamp byte?
	if ((b & 0x80) != 0 && !lastWasTimestamp) {		if ((b & 0x80) != 0 && !lastWasTimestamp) {
	lastWasTimestamp = true;		lastWasTimestamp = true;
	int lowTimestamp = b & TIMESTAMP_MASK_LOW;		mLowTimestamp = b & TIMESTAMP_MASK_LOW;
	if (lowTimestamp < previousLowTimestamp) {
			// If the low timestamp byte wraps within the packet then
			// increment the high timestamp byte.
			if (mLowTimestamp < previousLowTimestamp) {
	highTimestamp = (highTimestamp + 0x0080) & TIMESTAMP_MASK_HIGH;		highTimestamp = (highTimestamp + 0x0080) & TIMESTAMP_MASK_HIGH;
	}		}
	previousLowTimestamp = lowTimestamp;		previousLowTimestamp = mLowTimestamp;

	int newTimestamp = highTimestamp \| lowTimestamp;		// If the timestamp advances then send any pending data.
			int newTimestamp = highTimestamp \| mLowTimestamp;
	if (newTimestamp != currentTimestamp) {		if (newTimestamp != currentTimestamp) {
	if (dataCount > 0) {		// Send previous message separately since it has a different timestamp.
	// send previous message separately since it has a different timestamp		flushOutput(receiver);
	try {
	receiver.send(mBuffer, 0, dataCount, nanoTimestamp);
	} catch (IOException e) {
	// ???
	}
	dataCount = 0;
	}
	currentTimestamp = newTimestamp;		currentTimestamp = newTimestamp;
	}		}

	// calculate nanoTimestamp		// Calculate MIDI nanosecond timestamp from BLE timestamp.
	long now = System.nanoTime();		long now = System.nanoTime();
	nanoTimestamp = mTimeTracker.convertTimestampToNanotime(currentTimestamp, now);		mNanoTimestamp = mTimeTracker.convertTimestampToNanotime(currentTimestamp, now);
	} else {		} else {
	lastWasTimestamp = false;		lastWasTimestamp = false;
	mBuffer[dataCount++] = b;		// Flush if full before adding more data.
			if (mBytesInBuffer == mBuffer.length) {
			flushOutput(receiver);
	}		}
	}		mBuffer[mBytesInBuffer++] = b;

	if (dataCount > 0) {
	try {
	receiver.send(mBuffer, 0, dataCount, nanoTimestamp);
	} catch (IOException e) {
	// ???
	}		}
	}		}

			flushOutput(receiver);
	}		}
	}		}