Develop Reference

Why isOperational() in mobile vision text Recognizer in a device return true and in other return false?

Why isOperational() in mobile vision text recognizer returns false?
At first, mobile vision only show preview camera and after many tries to get the result, I saw that the texts recognized but in one device it works and in other device does not.
What should I do?
For example, in one device, isOperational() returns false, and it goes to readstate() and after that goes to looper() and stays on it!
in other device it only return false and doesn't go to looper.
I want ask other questions about it:
My first question is: how does isOperational() work? I can't understand it.
Maybe it goes to looper to download the native library in a queue and after many try, at last download completes and work. Can it be correct? Or is it just a bug that it goes to looper? Anywhere, what should I do?
Can I work on this when it works in one device I tried and in other does not? Or it must work in every device to I can work on it? And I get .apk from project but it can't install in devices, why?
Should it check for network?
Should it check for access to the memory?
note: it works with camera API and its deprecated. maybe the problem is with this!
TextRecognizer textRecognizer = new TextRecognizer.Builder(context).build();
textRecognizer.setProcessor(new OcrDetectorProcessor(graphicOverlay));
if (!textRecognizer.**isOperational**()) {
// Note: The first time that an app using a Vision API is installed on a
// device, GMS will download a native libraries to the device in order to do detection.
// Usually this completes before the app is run for the first time. But if that
// download has not yet completed, then the above call will not detect any text,
// barcodes, or faces.
//
// isOperational() can be used to check if the required native libraries are currently
// available. The detectors will automatically become operational once the library
// downloads complete on device.
Log.w(TAG, "Detector dependencies are not yet available.");
// Check for low storage. If there is low storage, the native library will not be
// downloaded, so detection will not become operational.*
IntentFilter lowstorageFilter = new IntentFilter(Intent.ACTION_DEVICE_STORAGE_LOW);
boolean hasLowStorage = registerReceiver(null, lowstorageFilter) != null;
if (hasLowStorage) {
Toast.makeText(this, R.string.low_storage_error, Toast.LENGTH_LONG).show();
Log.w(TAG, getString(R.string.low_storage_error));
}
}
*// Creates and starts the camera. Note that this uses a higher resolution in comparison
// to other detection examples to enable the text recognizer to detect small pieces of text.*
cameraSource =
new CameraSource.Builder(getApplicationContext(), textRecognizer)
.setFacing(CameraSource.CAMERA_FACING_BACK)
.setRequestedPreviewSize(1280, 1024)
.setRequestedFps(2.0f)
.setFlashMode(useFlash ? Camera.Parameters.FLASH_MODE_TORCH : null)
.setFocusMode(autoFocus ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO : null)
.build();
}
It doesn't produce any error and show preview camera but doesn't recognize texts in some devices.

AudioManager not working - neither turns on speakerphone nor mutes

In a WebRT app that does video chat, I want to set cell phones to play sound using speakerphone, not earpiece.
I've tried using the AppRTCAudioManager(which wraps AudioManager) to set mute and set speakerphone, using the AudioManager directly to set mute, placing the code in different methods, etc.
android.permission.MODIFY_AUDIO_SETTINGS is granted.
private void gotRemoteStream(MediaStream stream){
...
runOnUiThread(new Runnable() {
#Override
public void run() {
...
audioManager = AppRTCAudioManager.create(context);...
audioManager.start((x, y) -> {}) // a callback that does logging, omitted for clarity
// First try setting audio device with the AppRTCAudioManager, which wraps AudioManager.
audioManager.selectAudioDevice(AppRTCAudioManager.AudioDevice.SPEAKER_PHONE);
AppRTCAudioManager.AudioDevice ad = audioManager.getSelectedAudioDevice();
//Shows SPEAKER_PHONE, but sound still plays from earpiece.
// Next try it with the AudioManager itself.
AudioManager am = (AudioManager)context.getSystemService(Context.AUDIO_SERVICE);
am.setMode(AudioManager.MODE_IN_COMMUNICATION);
am.setMicrophoneMute(true);
am.setSpeakerphoneOn(true);
boolean mute = am.isMicrophoneMute(); //false
boolean on = am.isSpeakerphoneOn(); //false
}
The audioManager.getSelectedAudioDevice method shows the audio device as speakerphone, but am.isSpeakerphoneOn reveals that speakerphone is still off.
Also, setting the microphone to mute with am.setMicrophoneMute doesn't do anything. am.IsMicrophone mute still says false.
Thanks in advance for any help.
UPDATE: my cell phone mysteriously started playing thru speakerphone. But the AudioManager code still doesn't do anything. I changed the AudioManager code to select EARPIECE as the audio device, but now it still plays thru speakerphone.

Finally found the answer; I had mistyped the permission <uses-permission android:name="audioid.permission.MODIFY_AUDIO_SETTINGS"/>! Apparently the Android Studio compiler doesn't check for errors in the Manifest file. So it didn't alert me I had typed "audioid" instead of "android".

android - Why MediaPlayer delayes in playing mp3 audio?

I made a small app to practice audio playing in android using MediaPlayer, the app works great but there is a small delay of 1 second after clicking the play button and it's noticeable, I noticed this happens only when starting the audio file, when paused it resumes immediately with no delay,I googled around and seen people suggests using SoundPool instead of MediaPlayer but SoundPool is recommended for short audio clips while my app is playing a full song, what's the cause of this delay? is there a fix or work around this issue?
Here's my code:
private MediaPlayer mMediaPlayer;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mMediaPlayer = MediaPlayer.create(this,R.raw.this_is_america);
Button btnPlay = findViewById(R.id.btnPlay);
Button btnPause = findViewById(R.id.btnPause);
Button btnStop = findViewById(R.id.btnStop);
btnPlay.setOnClickListener(this);
btnPause.setOnClickListener(this);
btnStop.setOnClickListener(this);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnPlay:
Toast.makeText(getApplicationContext(), "Playing song",
Toast.LENGTH_SHORT).show();
mMediaPlayer.start();
break;
case R.id.btnPause:
Toast.makeText(getApplicationContext(), "Pausing song",
Toast.LENGTH_SHORT).show();
mMediaPlayer.pause();
break;
case R.id.btnStop:
Toast.makeText(getApplicationContext(), "Song stopped",
Toast.LENGTH_SHORT).show();
mMediaPlayer.reset();
mMediaPlayer = MediaPlayer.create(this,R.raw.this_is_america);
break;
}
}
Update: Turned out to be the mp3 audio file had silent pause at the beginning , tried another song and it works fine no noticeable delays , thank you greeble31 for suggesting to check that.

Your song has a silent pause at the beginning ;)
As #Lucefer mentioned, the Android platform has some small unavoidable latency due to the implementation of the audio stack. Or, at least it did a few years back, not sure what the current state of affairs is. At any rate, this delay is generally far too small (~10ms) to notice at the beginning of an audio file; it has more to do with response times for apps that simulate musical instruments and the like.

There is an audio latency issue in the Android operating system. There is a few milliseconds delay while audio recording and audio playing. You can learn more about this by navigating below URLs. And this latency is related to the device types.
https://developer.android.com/ndk/guides/audio/audio-latency
https://source.android.com/devices/audio/latency/measurements
You can use a native toolkit or native program (C, C++ ndk base) to minimize this latency. But you cannot do reduce it to 0Seconds. only minimize the latency.
There is https://superpowered.com/superpowered-android-media-server . You can get support from this but as I know you need to pay for it. I didn't try it. Therefore i don't know how much it reduced the latency.
If you want to remove silent part from your mp3. you can use ffmpeg wrapper for it. Go to https://github.com/WritingMinds/ffmpeg-android-java link there is a working ffmpeg wrapper for Android. you can easily use it.
using FFMPEG with silencedetect to remove audio silence you can find relevant FFmpeg command for it by navigating to this.
in the wrapper you don't need ffmpeg part. You need to replace it from -y. You can get those details when navigate to that wrapper

Android 6.0 (Marshmallow): How to play midi notes?

I'm creating an app that generates live instrument sounds and I'm planning on using the new Midi API featured in Android Marshmallow (version 6.0). I've read the package overview document here http://developer.android.com/reference/android/media/midi/package-summary.html and I know how to generate Midi notes but i'm still unsure: how do I actually play these notes after I've generated their Midi data?
Do I need a synthesizer program to play Midi notes? If so, do I have to make my own or is one provided by Android or a 3rd party?
I am a novice with Midi so please be as descriptive as possible with your answer.
What i've tried so far:
I've created a Midi manager object and opened an input port
MidiManager m = (MidiManager)context.getSystemService(Context.MIDI_SERVICE);
MidiInputPort inputPort = device.openInputPort(index);
Then, i've sent a test noteOn midi message to the port
byte[] buffer = new byte[32];
int numBytes = 0;
int channel = 3; // MIDI channels 1-16 are encoded as 0-15.
buffer[numBytes++] = (byte)(0x90 + (channel - 1)); // note on
buffer[numBytes++] = (byte)60; // pitch is middle C
buffer[numBytes++] = (byte)127; // max velocity
int offset = 0;
// post is non-blocking
inputPort.send(buffer, offset, numBytes);
I've also set up a class to receive the midi note messages
class MyReceiver extends MidiReceiver {
public void onSend(byte[] data, int offset,
int count, long timestamp) throws IOException {
// parse MIDI or whatever
}
}
MidiOutputPort outputPort = device.openOutputPort(index);
outputPort.connect(new MyReceiver());
Now, here's where i'm most confused. The use case of my app is to be an all-in-one composition & playback tool for making music. In other words, my app needs to contain or use a virtual midi device (like an intent of another app's midi synthesizer). Unless someone already made such a synthesizer, I must create one myself within my app's lifecycle. How do I actually actually convert a received midi noteOn() into sound coming out of my speakers? I'm especially confused because there also has to be a way to programmatically decide what type of instrument the note sounds like it's coming from: is this also done in a synthesizer?
Midi support in Android Marshmallow is fairly new so I haven't been able to find any tutorials or sample synthesizer apps online. Any insight is appreciated.

I haven't found any "official" way to control the internal synthesizer from Java code.
Probably the easiest option is to use the Android midi driver for the Sonivox synthesizer.
Get it as an AAR package (unzip the *.zip) and store the *.aar file somewhere in your workspace. The path doesn't really matter and it doesn't need to be inside your own app's folder structure but the "libs" folder inside your project could be a logical place.
With your Android project open in Android Studio:
File -> New -> New Module -> Import .JAR/.AAR Package -> Next -> Find
and select the "MidiDriver-all-release.aar" and change the subproject
name if you want. -> Finish
Wait for Gradle to do it's magic and then go to your "app" module's settings (your own app project's settings) to the "Dependencies" tab and add (with the green "+" sign) the MIDI Driver as a module dependency. Now you have access to the MIDI Driver:
import org.billthefarmer.mididriver.MidiDriver;
...
MidiDriver midiDriver = new MidiDriver();
Without having to worry anything about NDK and C++ you have these Java methods available:
// Not really necessary. Receives a callback when/if start() has succeeded.
midiDriver.setOnMidiStartListener(listener);
// Starts the driver.
midiDriver.start();
// Receives the driver's config info.
midiDriver.config();
// Stops the driver.
midiDriver.stop();
// Just calls write().
midiDriver.queueEvent(event);
// Sends a MIDI event to the synthesizer.
midiDriver.write(event);
A very basic "proof of concept" for playing and stopping a note could be something like:
package com.example.miditest;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import org.billthefarmer.mididriver.MidiDriver;
public class MainActivity extends AppCompatActivity implements MidiDriver.OnMidiStartListener,
View.OnTouchListener {
private MidiDriver midiDriver;
private byte[] event;
private int[] config;
private Button buttonPlayNote;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
buttonPlayNote = (Button)findViewById(R.id.buttonPlayNote);
buttonPlayNote.setOnTouchListener(this);
// Instantiate the driver.
midiDriver = new MidiDriver();
// Set the listener.
midiDriver.setOnMidiStartListener(this);
}
#Override
protected void onResume() {
super.onResume();
midiDriver.start();
// Get the configuration.
config = midiDriver.config();
// Print out the details.
Log.d(this.getClass().getName(), "maxVoices: " + config[0]);
Log.d(this.getClass().getName(), "numChannels: " + config[1]);
Log.d(this.getClass().getName(), "sampleRate: " + config[2]);
Log.d(this.getClass().getName(), "mixBufferSize: " + config[3]);
}
#Override
protected void onPause() {
super.onPause();
midiDriver.stop();
}
#Override
public void onMidiStart() {
Log.d(this.getClass().getName(), "onMidiStart()");
}
private void playNote() {
// Construct a note ON message for the middle C at maximum velocity on channel 1:
event = new byte[3];
event[0] = (byte) (0x90 | 0x00); // 0x90 = note On, 0x00 = channel 1
event[1] = (byte) 0x3C; // 0x3C = middle C
event[2] = (byte) 0x7F; // 0x7F = the maximum velocity (127)
// Internally this just calls write() and can be considered obsoleted:
//midiDriver.queueEvent(event);
// Send the MIDI event to the synthesizer.
midiDriver.write(event);
}
private void stopNote() {
// Construct a note OFF message for the middle C at minimum velocity on channel 1:
event = new byte[3];
event[0] = (byte) (0x80 | 0x00); // 0x80 = note Off, 0x00 = channel 1
event[1] = (byte) 0x3C; // 0x3C = middle C
event[2] = (byte) 0x00; // 0x00 = the minimum velocity (0)
// Send the MIDI event to the synthesizer.
midiDriver.write(event);
}
#Override
public boolean onTouch(View v, MotionEvent event) {
Log.d(this.getClass().getName(), "Motion event: " + event);
if (v.getId() == R.id.buttonPlayNote) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
Log.d(this.getClass().getName(), "MotionEvent.ACTION_DOWN");
playNote();
}
if (event.getAction() == MotionEvent.ACTION_UP) {
Log.d(this.getClass().getName(), "MotionEvent.ACTION_UP");
stopNote();
}
}
return false;
}
}
The layout file just has one button that plays the predefined note when held down and stops it when released:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.miditest.MainActivity"
android:orientation="vertical">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Play a note"
android:id="#+id/buttonPlayNote" />
</LinearLayout>
It is actually this simple. The code above could well be a starting point for a touch piano app with 128 selectable instruments, very decent latency and a proper "note off" functionality which many apps lack.
As for choosing the instrument: You'll just need to send a MIDI "program change" message to the channel on which you intend to play to choose one of the 128 sounds in the General MIDI soundset. But that's related to the details of MIDI and not to the usage of the library.
Likewise you'll probably want to abstract away the low level details of MIDI so that you can easily play a specific note on a specific channel with a specific instrument at a specific velocity for a specific time and for that you might find some clues from all the open source Java and MIDI related applications and libraries made so far.
This approach doesn't require Android 6.0 by the way. And at the moment only 4.6 % of devices visiting the Play Store run Android 6.x so there wouldn't be much audience for your app.
Of course if you want to use the android.media.midi package you could then use the library to implement a android.media.midi.MidiReceiver to receive the MIDI events and play them on the internal synthesizer. Google already has some demo code that plays notes with square and saw waves. Just replace that with the internal synthesizer.
Some other options could be to check out what's the status with porting FluidSynth to Android. I guess there might be something available.
Edit: Other possibly interesting libraries:
port of Java's javax.sound.midi package for abstracting the low level MIDI technical details
USB MIDI Driver for connecting to a digital piano/keyboard with a USB MIDI connector
MIDI over Bluetooth LE driver for connecting wirelessly to a digital piano/keyboard that supports MIDI over Bluetooth LE (like e.g. some recent Roland and Dexibell digital pianos)
JFugue Music library port for Android for further abstracting the MIDI details and instead thinking in terms of music theory

Do I need a synthesizer program to play Midi notes? If so, do I have to make my own or is one provided by Android or a 3rd party?
No, fortunately you don't need to make your own synthesizer. Android already has one built in: the SONiVOX Embedded Audio Syntehesizer. Android states in the docs on SONiVOX JETCreator:
JET works in conjunction with SONiVOX's Embedded Audio Synthesizer (EAS) which is the MIDI playback device for Android.
It wasn't clear whether or not you want real-time playback, or if you want to create a composition first and play it later within the same app. You also state that you want to play midi notes, not files. But, just so you know, Midi playback is supported on android devices. So playing a .mid file should be done the same way you would play a .wav file using MediaPlayer.
To be honest, I haven't use the midi package, or done midi playback, but if you can create a .mid file and save it to disk, then you should be able to play it back using straight MediaPlayer.
Now, if you want to play straight midi notes, not files, then you can use this mididriver package. Using this package you should be able to write midi data to the Embedded Synthesizer:
/**
* Writes midi data to the Sonivox synthesizer.
* The length of the array should be the exact length
* of the message or messages. Returns true on success,
* false on failure.
*/
boolean write(byte buffer[])
If you want to step even lower than that, you could even play straight PCM using AudioTrack.
For additional info, here is a blog post I found from someone who seemed to have similar troubles to yours. He states:
Personally I solved the dynamic midi generation issue as follows: programmatically generate a midi file, write it to the device storage, initiate a mediaplayer with the file and let it play. This is fast enough if you just need to play a dynamic midi sound. I doubt it’s useful for creating user controlled midi stuff like sequencers, but for other cases it’s great.
Hope I covered everything.

To generate sound using Android MIDI API, you need a synthesizer app which accepts MIDI input. Unfortunately, this is the only such app I have found on Google Play:
https://play.google.com/store/apps/details?id=com.mobileer.midisynthexample
I was able to play music by sending note on and note off messages to this app. But program change worked poorly. Unless I did something wrong in my code, it seems the app has only two instruments.
However, there are some guys working on other synthesizer apps, so I expect more apps will be available soon. This app looks promising, though I haven't tested it myself yet:
https://github.com/pedrolcl/android/tree/master/NativeGMSynth

Java set MIDI Out receiver

Hey I am trying to send MIDI data from a Java class to a MIDI device connected via USB. I did this once like 2 years ago and it worked, but I somehow can't find the project anymore.
The example Java code runs fine;
myMsg = new ShortMessage();
myMsg.setMessage(ShortMessage.NOTE_ON, 0, 60, 93);
timeStamp = -1;
Receiver rcvr = MidiSystem.getReceiver();
rcvr.send(myMsg, timeStamp);
Simple stuff. 5 lines of code and the message appears on the device. The problem is, that this way, only the standard device is set up and ready to receive MIDI. I can't ask my users to set the device of desire as standard device every time they want to use my application. (the Receiver acts as output destination/port to the input of the physical device I am connected to)
I am now trying to set up the Receiver by doing the following:
MidiDevice.Info[] infoA=MidiSystem.getMidiDeviceInfo();//array where all the device info goes
for (int x=0;x<infoA.length;x++){
System.out.println("in "+infoA[x]); //this displays all the devices
}
MidiSystem.getMidiDevice(infoA[d]); //d is set to an integer that represents the item number on the device list of the device I wanna send MIDI to
System.out.println(infoA[d]);//last check if the correct device is selected
MidiDevice MidiOutDevice = MidiSystem.getMidiDevice(infoA[d]); //setting this to "my" device in order to set the Receiver
maschineReceiver= MidiOutDevice.getReceiver();
Sequencer MidiOutSequencer = MidiSystem.getSequencer();
MidiOutSequencer.getTransmitter().setReceiver(maschineReceiver); //probably unnecessary last 2 line but I gave this a try in case it helps
if I now do maschineReceiver.send(myMsg, timeStamp);, nothing happens at all. I also tried different devices but it didn't get any better. I am sure it can't be a very hard difficult thing to do as it something I actually achieved 2 years ago when my coding skills were awful but I just can't find the mistake right now, no matter how often I reread the Java documentation, it just won't work whatever I do.
Thanks in advance

To actually reserve a device for your program, you need to use the MidiDevice method open:
if (!(device.isOpen())) {
try {
device.open();
} catch (MidiUnavailableException e) {
// Handle or throw exception...
}
}