Skip to content

Most visited

Recently visited

navigation
MidiScope / src / com.example.android.common.midi /

MidiFramer.java

1
/*
2
 * Copyright (C) 2015 The Android Open Source Project
3
 *
4
 * Licensed under the Apache License, Version 2.0 (the "License");
5
 * you may not use this file except in compliance with the License.
6
 * You may obtain a copy of the License at
7
 *
8
 *      http://www.apache.org/licenses/LICENSE-2.0
9
 *
10
 * Unless required by applicable law or agreed to in writing, software
11
 * distributed under the License is distributed on an "AS IS" BASIS,
12
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13
 * See the License for the specific language governing permissions and
14
 * limitations under the License.
15
 */
16
 
17
package com.example.android.common.midi;
18
 
19
import android.media.midi.MidiReceiver;
20
import android.util.Log;
21
 
22
import java.io.IOException;
23
 
24
/**
25
 * Convert stream of arbitrary MIDI bytes into discrete messages.
26
 *
27
 * Parses the incoming bytes and then posts individual messages to the receiver
28
 * specified in the constructor. Short messages of 1-3 bytes will be complete.
29
 * System Exclusive messages may be posted in pieces.
30
 *
31
 * Resolves Running Status and interleaved System Real-Time messages.
32
 */
33
public class MidiFramer extends MidiReceiver {
34
    private MidiReceiver mReceiver;
35
    private byte[] mBuffer = new byte[3];
36
    private int mCount;
37
    private byte mRunningStatus;
38
    private int mNeeded;
39
    private boolean mInSysEx;
40
 
41
    public MidiFramer(MidiReceiver receiver) {
42
        mReceiver = receiver;
43
    }
44
 
45
    /*
46
     * @see android.midi.MidiReceiver#onSend(byte[], int, int, long)
47
     */
48
    @Override
49
    public void onSend(byte[] data, int offset, int count, long timestamp)
50
            throws IOException {
51
        int sysExStartOffset = (mInSysEx ? offset : -1);
52
 
53
        for (int i = 0; i < count; i++) {
54
            final byte currentByte = data[offset];
55
            final int currentInt = currentByte & 0xFF;
56
            if (currentInt >= 0x80) { // status byte?
57
                if (currentInt < 0xF0) { // channel message?
58
                    mRunningStatus = currentByte;
59
                    mCount = 1;
60
                    mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
61
                } else if (currentInt < 0xF8) { // system common?
62
                    if (currentInt == 0xF0 /* SysEx Start */) {
63
                        // Log.i(TAG, "SysEx Start");
64
                        mInSysEx = true;
65
                        sysExStartOffset = offset;
66
                    } else if (currentInt == 0xF7 /* SysEx End */) {
67
                        // Log.i(TAG, "SysEx End");
68
                        if (mInSysEx) {
69
                            mReceiver.send(data, sysExStartOffset,
70
                                offset - sysExStartOffset + 1, timestamp);
71
                            mInSysEx = false;
72
                            sysExStartOffset = -1;
73
                        }
74
                    } else {
75
                        mBuffer[0] = currentByte;
76
                        mRunningStatus = 0;
77
                        mCount = 1;
78
                        mNeeded = MidiConstants.getBytesPerMessage(currentByte) - 1;
79
                    }
80
                } else { // real-time?
81
                    // Single byte message interleaved with other data.
82
                    if (mInSysEx) {
83
                        mReceiver.send(data, sysExStartOffset,
84
                                offset - sysExStartOffset, timestamp);
85
                        sysExStartOffset = offset + 1;
86
                    }
87
                    mReceiver.send(data, offset, 1, timestamp);
88
                }
89
            } else { // data byte
90
                if (!mInSysEx) {
91
                    mBuffer[mCount++] = currentByte;
92
                    if (--mNeeded == 0) {
93
                        if (mRunningStatus != 0) {
94
                            mBuffer[0] = mRunningStatus;
95
                        }
96
                        mReceiver.send(mBuffer, 0, mCount, timestamp);
97
                        mNeeded = MidiConstants.getBytesPerMessage(mBuffer[0]) - 1;
98
                        mCount = 1;
99
                    }
100
                }
101
            }
102
            ++offset;
103
        }
104
 
105
        // send any accumulatedSysEx data
106
        if (sysExStartOffset >= 0 && sysExStartOffset < offset) {
107
            mReceiver.send(data, sysExStartOffset,
108
                    offset - sysExStartOffset, timestamp);
109
        }
110
    }
111
 
112
}
This site uses cookies to store your preferences for site-specific language and display options.

Get the latest Android developer news and tips that will help you find success on Google Play.

* Required Fields

Hooray!

Browse this site in ?

You requested a page in , but your language preference for this site is .

Would you like to change your language preference and browse this site in ? If you want to change your language preference later, use the language menu at the bottom of each page.

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.

Take a short survey?
Help us improve the Android developer experience.
(Sep 2017 survey)