Develop Reference

DTMF receiving in Android

my main goal is to get DTMF tones in my Android app and perform related actions. I've seen that TelephonyManager can send DTMF but there is no method to receive them. I came across many pages (most of them quite old) which suggest the use of FFT libraries through buffering the VOICE_DOWNLINK audio stream with AudioRecorder (setting proper permissions in the manifest). I tried both with AudioRecorder and MediaRecorder (which is mainly intended for creating file) as well as "Visulizer" class which contains a proper getFft methos out of the box but none of them can access MediaRecorder.AudioSource.VOICE_DOWNLINK & co even if permissions are correctly managed and granted.
uses-permission android:name="android.permission.RECORD_AUDIO"
None of the Visualizer/MediaRecorder/AudioRecorder get initialized and I'm getting frustrated by the fact that I'm chasing after record permissions in order to listen for DTMF tones. Is there any other way I'm not considering?

After many research it appears impossible since
There is no DTMF listen method (Google... why??)
There are limitation accessing other's phone audio to FFT.
Especially related to this last point I've seen that basically all app based on a common used Google/GitHub code (https://github.com/pjasiun/dtmf-decoder) crashes from a certain SDK during calls. They all work fine with phone mic which is useless for phonecalls
Leaving this post for other people. For my purposes I resolved with an Arduino DTMF recognizer.

Retrieving the application name that has audio focus change

I can't seem to find anything related to finding out what application got audio focus. I can correctly determine from my application what type of focus change it was, but not from any other application. Is there any way to determine what application received focus?
"What am I wanting to do?"
I have managed to record internal sound whether it be music or voice. If I am currently recording audio no matter the source, I want to determine what application took the focus over to determine what my application need's to do next.
Currently I am using the AudioManager.OnAudioFocusChangeListener for my application to stop recording internal sounds once the focus changes, but I want the application's name that gained the focus.

Short Answer: There's no good solution... and Android probably intended it this way.
Explanation:
Looking at the source code, AudioManager has no API's(even hidden APIs) for checking who has Audio Focus. AudioManager wraps calls to AudioService which holds onto the real audio state. The API that AudioService exposes through it's Stub when AudioManager binds to it also does not have an API for querying current Audio Focus. Thus, even through reflection / system level permissions you won't be able get the information you want.
If you're curious how the focus changes are kept track of, you can look at MediaFocusControl whose instance is a member variable of AudioService here.
Untested Hacky Heuristic:
You might be able to get some useful information by looking at UsageStats timestamps. Then once you have apps that were used within say ~500ms of you losing AudioFocus you can cross-check them against apps with Audio Permissions. You can follow this post to get permissions for any installed app.
This is clearly a heuristic and could require some tuning. It also requires the user to grant your app permissions to get access to the usage stats. Mileage may vary.

Looking at the MediaContorller class (new in lollipop, available in comparability library for older versions).
There are these two methods that look interesting:
https://developer.android.com/reference/android/media/session/MediaController.html#getPackageName()
https://developer.android.com/reference/android/media/session/MediaController.html#getSessionActivity()
getPackageName supposedly returns the current sessions package name:
http://androidxref.com/5.1.1_r6/xref/frameworks/base/media/java/android/media/session/MediaController.java#397
getSessionActivity gives you a PendingIntent with an activity to start (if one is supplied), where you could get the package as well.
Used together with your audio listener and a broadcast receiver for phone state to detect if the phone is currently ringing you might be able to use this in order to get a more fine grained detection than you currently have. As Trevor Carothers pointed out above, there is no way to get the general app with audio focus.

You can use dumpsys audio to find who are using audio focus. And, you can also look into the results of dumpsys media_session.
And, if you want to find who're playing music, you can choose dumpsys media.audio_flinger. For myself, I switch to this command.

AUDIO_OUTPUT_FLAG_FAST denied by client

I'm getting this AudioTrack warning
AUDIO_OUTPUT_FLAG_FAST denied by client
in my Android app for a button I'm subclassing. I can hear a click when tapping on the button so is this anything to worry about?
Note: I'm not getting the mismatching sample rate message as in this question: AudioTrack: AUDIO_OUTPUT_FLAG_FAST denied by client due to mismatching sample rate

Most likely, the tap sound got a AUDIO_OUTPUT_FLAG_FAST in order to use low-latency playback if possible, but the AudioTrack class considered the track settings to be incompatible with the low-latency audio output, so the flag got removed and the track got treated as if the flag hadn't been set to begin with. So I wouldn't consider this to be something to worry about.
As for the reason why the flag got denied; I'd still say that the most probable reason is a sample rate mismatch. The log in the question you linked to appears to have been added in this commit to the AOSP. But if we look at the master branch of the code base used on many Qualcomm-based devices we see that it still has the "AUDIO_OUTPUT_FLAG_FAST denied by client" log in the case were there was a sample rate mismatch. Which logs you get depends on the exact implemetation running on your device (i.e. which device and Android version you're running).

Try changing the sample rate at
"frameworks/base/
frameworks/av/
hardware/libhardware" locations.
default sample rate is 44100 try setting the sample rate you want (your audio files have).
it will work.
cheers.

I had the same problem, my problem was caused because I forgotten type activity define in manifest file. such as : activity android:name=".NFCReaderActivity"

Playing Audio During call so that other person on call can hear it

i am developing one application which
needs to play an audio song to callee when call is lifted by callee,
and automatically call has to be disconnected automatically when audio
song playing completed . i tried to find in android API for any
classes or methods to do this, but failed to find... please help me
how to do this..
your answer could be helpful to me...please do reply
Thank you in advance..

AFAIK, it is not possible to play a sound in the ongoing call and also to automatically dosconnect a call. Telephont API doesnt provide any methods to do any od these. So both od these requirement can't be fullfilled in ANdroid.

Voice recognition on android with recorded sound clip?

I've used the voice recognition feature on Android and I love it. It's one of my customers' most praised features. However, the format is somewhat restrictive. You have to call the recognizer intent, have it send the recording for transcription to google, and wait for the text back.
Some of my ideas would require recording the audio within my app and then sending the clip to google for transcription.
Is there any way I can send an audio clip to be processed with speech to text?

I got a solution that is working well to have speech recognizing and audio recording. Here is the link to a simple Android project I created to show the solution's working. Also, I put some print screens inside the project to illustrate the app.
I'm gonna try to explain briefly the approach I used. I combined two features in that project: Google Speech API and Flac recording.
Google Speech API is called through HTTP connections. Mike Pultz gives more details about the API:
"(...) the new [Google] API is a full-duplex streaming API. What this means, is that it actually uses two HTTP connections- one POST request to upload the content as a “live” chunked stream, and a second GET request to access the results, which makes much more sense for longer audio samples, or for streaming audio."
However, this API needs to receive a FLAC sound file to work properly. That makes us to go to the second part: Flac recording
I implemented Flac recording in that project through extracting and adapting some pieces of code and libraries from an open source app called AudioBoo. AudioBoo uses native code to record and play flac format.
Thus, it's possible to record a flac sound, send it to Google Speech API, get the text, and play the sound that was just recorded.
The project I created has the basic principles to make it work and can be improved for specific situations. In order to make it work in a different scenario, it's necessary to get a Google Speech API key, which is obtained by being part of Google Chromium-dev group. I left one key in that project just to show it's working, but I'll remove it eventually. If someone needs more information about it, let me know cause I'm not able to put more than 2 links in this post.

Unfortunately not at this time. The only interface currently supported by Android's voice recognition service is the RecognizerIntent, which doesn't allow you to provide your own sound data.
If this is something you'd like to see, file a feature request at http://b.android.com. This is also tangentially related to existing issue 4541.

As far as I know there is still no way to directly send an audio clip to Google for transcription. However, Froyo (API level 8) introduced the SpeechRecognizer class, which provides direct access to the speech recognition service. So, for example, you can start playback of an audio clip and have your Activity start the speech recognizer listening in the background, which will return results after completion to a user-defined listener callback method.
The following sample code should be defined within an Activity since SpeechRecognizer's methods must be run in the main application thread. Also you will need to add the RECORD_AUDIO permission to your AndroidManifest.xml.
boolean available = SpeechRecognizer.isRecognitionAvailable(this);
if (available) {
SpeechRecognizer sr = SpeechRecognizer.createSpeechRecognizer(this);
sr.setRecognitionListener(new RecognitionListener() {
#Override
public void onResults(Bundle results) {
// process results here
}
// define your other overloaded listener methods here
});
Intent intent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
// the following appears to be a requirement, but can be a "dummy" value
intent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE, "com.dummy");
// define any other intent extras you want
// start playback of audio clip here
// this will start the speech recognizer service in the background
// without starting a separate activity
sr.startListening(intent);
}
You can also define your own speech recognition service by extending RecognitionService, but that is beyond the scope of this answer :)