Background
Phone recording is not really supported on Android, yet some devices support it to some extend.
This made various call recording apps gather as much possible information about devices and what should be done to them, and decide upon this what to do.
Some even offer root solutions.
One such example is boldbeast Call Recorder app, which offers a lot of various configurations to change:
"record mode" . Shows 14 modes for non-rooted devices, and up to 34 for rooted. Also shows "Alsa mode" as an option for it, for rooted devices.
Has "Tune Audio Effect ("auto tune a groupd of parameters") .
Has "Tune Audio Route", with the possible values of "Disabled", "Group1", "Group2", "Group3"
For rooted devices:
"change audio controls" ("auto change audio controls")
"change audio driver" (change audio drive settings to enable record mode 21,22,23,24,31,32,33,34")
For rooted devices: "start input stream"
The problem
If I'm in need to create a call recording app, there is no other way than to find the various workarounds for various devices, but as it seems other apps use terms that don't appear in the API.
I can't find any of those of the app I've mentioned, for example.
What I've found
Other than tons of questions of how to record calls on Android, showing that it doesn't work on all devices, I could find some interesting things. Here are my tries and insights so far:
There are some Audio recording sources we can use while preparing the recording (docs here) , but sadly in each device it might be different. For some, VOICE_CALL works, and for some, others. But at least we can try...
On OnePlus 2 with Android 6.0.1, incoming calls can be recorded using VOICE_CALL, but I can't make outgoing calls be recorded there, unless I use MIC as audio source together with speaker turned on. Somehow, the app I've mentioned succeeds recording it without any issues. I'm sure I will see other issues with other Android devices, as I've tried to address this whole topic in the past. Update: I've found this sample project (also here), which for some reason sleeps for 2 seconds on the UI thread between prepare and start calls of the mediaRecorder. It works fine, and when I did something similar (wait using Handler.postDelayed for 1 second), it worked fine too. The comment that was written there is "Sometimes prepare takes some time to complete".
On Galaxy S7 with Android 8, I've failed to get sound of the other side for outgoing calls AND incoming calls (even with MIC and speaker), no matter what I did, yet the app I've mentioned worked fine.
To let you try my POC of call recording, I've published an open source github repository here, having a sample that will record a single call, and let you listen to the most recent one, if all works well.
This "ViktorDegtyarev - CallRecLib" SDK , which doesn't seem to work at all, and crashes on various Android versions
These 2 old sample projects : rvoix , esnyder-callrecorder , both fail to actually record. The second doesn't even seem to work on Android 6.0.1 device, which it's supposed to support.
aykuttasil - CallRecorder sample and axet - android-call-recorder sample - both, just like on my POC, don't have any tweaking except for AudioSource, and because of this they fails to record on some cases, such as OnePlus 2 output-audio of outgoing calls.
Most third party apps only offer the AudioSource tweaking, but some (like "boldbeast") do offer more. One example is "Automatic Call Recorder" which has "configuration" (10 values to choose from, first is "default") and "method" (5 vales to choose from, first is "default"). Those apps probably do not want others to understand what those configurations mean, so they put general names. Or, it's just too complicated for everyone (especially for users), so they generalize the names.
There is an API of "setMode" here, but it doesn't seem to change upon calling it. I was thinking of maybe change the "channel" of where the call is being used, this way, but it doesn't work. It stays on the value of "2" during call, which is MODE_IN_CALL.
There are customized parameters that are available for various devices (each OEM and its own parameters), which can be set here and maybe even via JNI (here and here) , but I don't get where to get this information from (meaning which pairs of key-value are available). I've searched in a lot of places, but couldn't find any website that talks about which possible parameters are available, and for which devices.
I was thinking of using AudioRecord instead of MediaRecorder class for recording, thinking that it's a bit low level, so it could give me more power and access to customized capabilities, but it seems to be very similar to MediaRecorder, and even use the same audio sources (example here).
Another try I had with low level API, was even further, of using JNI (OpenSL ES for Android). For this, I couldn't find much information (except here and here), and only found the 2 samples of Google here (called "audio echo" and "native audio"), which are not about recording sound, or at least I don't see them occur.
Android P might have official way to record calls (read here and here). Testing on my Android P DP3 device (Pixel 2), I could record both sides fine in both incoming and outgoing calls, using "DEFAULT" as audio source, so maybe the API will finally be official and work on all Android versions. I wrote about it here and here.
I was thinking that maybe the Visualizer class could be a workaround of recording, but according to some StackOverflow post (here), the quality it extremely low, so I decided that maybe I shouldn't try it. Plus I couldn't find a sample of how to record from it.
I've found some parameters that might be available on some devices, here (found from here), all start with "AUDIO_PARAMETER_", but testing on Galaxy S7, all returned empty string. I've also found this website, that gave me the idea of using audioManager.setParameters("noise_suppression=off") together with MIC audio source, but this didn't seem to do anything in the case of Galaxy S7.
The questions
As opposed to other similar questions about this topic, I'm not asking how to record calls. I already know it's a very problematic and complex problem. I already know I will have to address various configurations, and that I will probably use a server to store all of them and find there the best match for each one.
What I want to ask is more about the tweaking and workarounds :
Is there a list of configurations for the various devices, Android versions, and what to choose for each?
Besides Audio source, which other configuration is possible to be used?
Which parameters are possible for the various devices and Android versions ? Are there any websites of the OEMs describing them?
What are the various terms in the app I've mentioned? Where can I find information of how to change them?
Which tools are available for rooted devices?
Is it possible to know which device supports call recording and which not, by using the API ?
About the workaround of OnePlus 2, to wait a moment till we start recording, why is it needed? Is it needed on all Android versions? Is it a known issue? Would 1 second be enough?
How come on the Galaxy S7 I've failed to record the other side even when using MIC&speaker?
EDIT: I've found this of accessibility service being able to help with call recording:
https://developer.android.com/guide/topics/media/sharing-audio-input#voice_call_ordinary_app
Not sure how to use it though. It seems "ACR Phone Dialer" uses it. If anyone knows how it can be done, please let me know.
I spent many weeks working on a Voicecall Recording App so I faced all your issues/questions/problems.
Moreover: my project had a low-priority so I didn't spent much time every day on it, so I worked on this App for many months while Android was changing under the hood (minor an major releases).
I was developing always on the same Galaxy Note 5 using its stock ROM (without Root) but I discovered that on the same device the behaviour was changing from one Android release to another without any explanation.
For example from Nougat 7.0 to 7.1.2 I was unable to record a voicecall using the same code as before.
Google has enforced_or_changed restrictions about voicecall recording many times.
At the beginning it was sufficient to use use VOICE_CALL AudioSource. Then manufactures has started to interprete this Value as they wanted, and the result was that one implementation was working well but another was not.
Then Reflection was needed to run undocumented/hidden methods to start voicecall recording.
Then Google has added a Runtime check, so calling them directly was not more possible even using Reflection.
However this method lack of stability because it was not guarantee that a method was using the same name on all devices.
Then I started to reverse-engineer currently working Apps that were working on newer Android version and I discovered that them were using a complete different and more secure approach. This takes me many weeks because all these Apps uses JNI Libraries trying to hide this method between Assembler code.
When I succesfully create a Test App which was recording well I tried the SAME code in many different devices and ROMs/Versions and surprisely it was working well.
This means that all those different methods you can see in these App Settings (I'm 98% sure about it) are just "fake" or just refers to OLD methods not more used.
A small different metion should be done for Rooted devices:
these devices could change AudioRoutes so a different approach can be used in this case.
[1] There isn't any list or website listing all supported devices or best method to do a successfully voicecall record
[6] It's not possibile to know which device supports Voicecall Recording
just using an API call. You have to try and catch Excepions...
[8] Recording by MIC+speaker suffers of many issues: (1) the caller will hear all your ambient sound so the privacy-bug is a big issue (2) the echo is a big problem (3) the recording volume is very low as the quality of recordered voice
According to my tests, one way to improve this is to have an AccessibilityService being active (no need to write there anything at all) while choosing voice-recognition as the audio source. Also it's recommended to have the speaker turned on because this will record the audio from the microphone.
This seems to exist in some call-recording apps.
Weird thing is that Google has written this as a rule on the Play Store:
The Accessibility API is not designed and cannot be requested for
remote call audio recording.
https://support.google.com/googleplay/android-developer/answer/11899428
No idea what the "remote" means here.
Anyway, I've updated the Github repository to include these additions.
Skip the first two paragraphs if your not interested in why I'm asking this question.
Here is the situation: I'm using a Moto Z Play with the Projector Modification, the mod is really cool and allows me to literally project my phone screen onto the wall. I've been writing a personal assistant program that helps me with my daily life I.E. Sorting gmails, reminding me of calendar events, keeping track of anything I want it to remember and reminding me of those things when I've asked it to, and much more. Its basically a personal secretary.
One new feature I just added was a habit tracker. I created a small graphical interface on my phone using Tasker that would email my "assistant" who would then record the habit and create a really cool graph that shows my past habit record as well as using a neural network to predict the next days habit. Only problem is, the graph got really intricate really fast. I want to show a months worth of habits (16 total habits), creating what can be up to a 16 x 31 floating point graph with labels. My laptop screen is just not big enough to display all of that without it just being a mess! I really want to display the graph from my projector mod, the entire wall will definitely be big enough to show all that data.
Ok, now my question (thanks for hanging in there I know that was a lot):
Is there any way that I can display an image on my phone from a Python program without creating a standalone app? Even if my phone needs to be plugged into my computer to stream the data through a cable.
I would use a service like Kivy to create a standalone app, but then it wouldn't be hooked up to my assistant, completely defeating the purpose.
I'm not looking for anything similar to a notification, I really want to draw over the entire screen of my phone. This is something I did with Processing (Java library) a while back, but now I'm using Python because it's more machine learning friendly.
I've looked into a lot of services but nothing seems to be able to do this. Remember that I dont need to send anything back from my phone, simply display an image on the screen until the desktop side program tells it to stop.
Not my expertise but if I would need to do something like that I would make a web-service of the python app using django and go to the url with my phone. Don't know if it help....
Regardless of "how" or "what", the answer is, you will always need some software running on the Android to capture the stream of data (images) and display it in the screen.
The point is, you don't have to write this software yourself. The obvious example that come to mind is use any DLNA compatible software, VLC for example, and have your python to generate a h264 stream and point VLC to it. Another way would be use some http service from your python and simply load it in the browser.
hope it helps.
I am taking this crazy class on Moble Programming. We have to do a final project and I would like to do some sort simple guitar processor app.
I wanted to do this in IOS, but it seems like the learning curve for IOS is to impractical for a short class.
No offense to anyone but Droid is easier to program, at least to me, but I am confused if you can even get guitar input from a jack (not mic) and then do some processing on the input and feed it to the output.
I'm aware of latency, which may or may not be a big deal for a class.
Does anyone know if Droid can do anything like this? If so any articles or somewhere to start? I know with IOS you can at least buy a jack and it seems to have tons of open source processing code, but I can't seem to find anything for Droid. All I have seen is "Ghetto Amp" for guitar stuff.
Any ideas?
Thanks
You may want to look at this project:
http://code.google.com/p/moonblink/wiki/Audalyzer
should be pretty useful :)
However the core class you will be using to pick up and look at audio streams is: http://developer.android.com/reference/android/net/rtp/AudioStream.html
I wrote a MIDI guitar for a college project a long time ago, in assembly for a Texas Instruments DSP. As long as you just played exactly one note, and were really careful about it, it could tell what you'd played.
Not much amplification was needed. In fact, I could get some notes even on an unamplified signal. I had oscilloscopes and a pretty generalized ADC to work with, you might have to amplify the signal...but if you do, be careful not to fry your input. Start low...and really, the more you can read up on the tolerances the better.
Looks like they never made any hi-fi micro-USB 24-bit ADCs or wrote drivers for them. I guess there's no market. :) But if you're doing a school project and not producing the latest Muse album, get a path from your guitar to the headset line in:
http://androidforums.com/android-media/194740-questions-about-audio-recording-droid.html
I'd probably just sacrifice a cheap or broken headset to get the headset plug. ( Maybe they sell appropriate tips at Radio Shack but I've learned not to assume such things anymore :-/ ) After building a cable I'd I'd feed it an amplified signal from the guitar so I could control the gain level to whatever I wanted.
Depending on latency requirements you can use Java or NDK. Note this answer:
Need help about sound processing
(I have one of the original Droids sitting around in a drawer, I'm sure I could use it for something but I just haven't figured out what!)
I have searched for this online, but am still a bit confused (as I'm sure others will be if they think of something like this). I'd like to preface by saying that this is not for homework and/or profit.
I wanted to create an app that could listen to your microwave as you prepare popcorn. It would work by sounding an alarm when there's a certain time interval between pops (say 5-6 seconds). Again, this is simply a project to keep me occupied - not for a class.
Either way, I'm having trouble trying to figure out how to analyze the audio intake in real-time. That is, I need a way to log the time when a "pop" occurs. So that you guys don't think I didn't do any research into the matter, I've checked out this SO question and have extensively searched the AudioRecord function list.
I'm thinking that I will probably have to do something with one of the versions of read() and then compare the recorded audio every 2 seconds or so to the recorded audio of a "pop" (i.e. if 70% or more of the byte[] audioData array is the same as that of a popping sound, then log the time). Can anyone with Android audio input experience let me know if I'm at least on the right track? This is not a question of me wanting you to code anything for me, but a question as to whether I'm on the correct track, and, if not, which direction I should head instead.
I think I have an easier way.
You could use the MediaRecorder 's getMaxAmplitude method.
Anytime your recorder detects a big jump in amplitude, you have detected a corn pop!
Check out this code (ignore the playback part): Playing back sound coming from microphone in real-time
Basically the idea is that you will have to take the value of each 16-bit sample (which corresponds to the value of the wave at that time). Using the sampling rate, you can calculate the time between peaks in volume. I think that might accomplish what you want.
this may be a bit overkill, but there is a framework from MIT media labs called funf: http://code.google.com/p/funf-open-sensing-framework/
They already created classes for audio input and some analysis (FFT and the like), also saving to files or uploading is implemented as far as I've seen, and they handle most of the sensors available on the phone.
You can also get inspired from the code they wrote, which I think is pretty good.
I noticed that Flash allows you to insert cue's into a video file (flv). Is something like this possible on Android? I have a video that runs locally in my Android app and I would like to insert cues into the video which will give me callbacks when a certain portion of the video has been reached. If this is not possible, are there any other methods to do something similar? I have to be pretty precise with where the cue is located.
Thanks
Note:
I just found this same question on stackoverflow. Can anyone verify that this is still the case? (That it is not possible, only by polling the video continually). I did know of this way, but it's not the most accurate way if you need to be precise and stich dynamic pieces of video together seamlessly.
Android VideoView - Detect point of time in video
I´m working on this as well and a kind of cue/action scripts. For tutorials, instruction video I need to keep track of current position to serve for example questions and navigation menus appropriate for that point in time. Easy when it´s sufficient to act in response to user input but otherwise firing up a thread to poll at some decent interval is the thing. Accuracy might be acceptable and can be calibrated by sensing actual position.