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usbaudiosupport

Support for USB audio interfaces

Audio Evolution Mobile version 1.8.0 or higher has support for external USB audio interfaces. Using such a device can turn your Android device into a professional mobile recording studio! There are more than a hundred different USB audio devices around, ranging from simple low-cost USB 'dongles' (6 to 10 euro), via entry level quality devices (Lexicon Alpha, M-Audio Fast Track Pro, 40 to 80 euro) to high-end multichannel devices like the FocusRite 18i6 or Presonus 1818VSL (over 300 euro). There is always a device for your budget!

Note: the use of USB audio interfaces requires an in-app purchase or the purchase of USB Audio Recorder PRO!

The advantages

  • Quality: the audio quality of these devices quickly raises far above the built-in mic and A/D and D/A converters of your Android device. You'll be able to record in higher sample rates and higher resolutions when your USB audio interface supports it.
  • Connectivity: proper XLR inputs with high quality pre-amps, quarter-inch jacks for line inputs (*)
  • Control input gain: almost all USB audio devices will let you control the input gain, something which Android lacks completely (*)
  • Zero-latency monitoring: use zero-input latency hardware monitoring to hear directly what you are recording, also not present on Android. (*)
  • Lower latency: our USB audio system talks directly to the hardware without the Android audio layer in between
  • Very low latency jitter: the variation in latency each time you record can be dramatically high using the Android audio system (up to half a second!). With our USB audio system, this jitter is limited to one or a couple of milliseconds)
  • Multichannel recording: when your Android device is capable enough, you can even record more than two channels at the same time if your USB audio interface has more than two inputs.

Note that some features like multichannel and 24-bit recording are only possible on certain Android configurations. Please read the section on compatibility for further information.

(*) = When the USB audio interface supports it

Compatibility

There are three basic rules that determine if your Android/USB audio device combination will work:

  1. Your Android device runs Android 3.1 or higher
  2. Your Android device supports USB host mode (most often you need an OTG cable to enable it)
  3. Your USB audio interface is 'class compliant'

Your Android device does NOT need to be rooted. To find out if your Android device supports USB host mode, you can either look in our compatibility list, Google for it, or look at a good phone website like http://www.phonearena.com. Enter your phone model there in the search field and select your device. Then look at Connectivity and see if it says 'USB host'.

Whether a USB audio interface is 'class compliant' or not is harder to determine. If the device does not require specific drivers under Windows or OSX, then there are good chances it will work. Look in our compatibility list if your device is there. If it's not, then you could simply try it out with the free trial version of USB Audio Recorder PRO or the demo version of Audio Evolution Mobile (2 minute recording limit), or in the full version with a 30-second limit and a couple of recordings.

Compatibility list

Please look on our USB Audio Recorder PRO webpage for a list of known working and non-working Android and USB audio devices.

VERY IMPORTANT NOTE: if you want to use a USB audio interface with Audio Evolution Mobile, please make sure to try our free trial version Audio Evolution Mobile Demo first!!. If you do not have a USB audio interface yet, please see our compatibility list as well or ask us by email.

Caveats

  • Some Android devices have USB host, but lack certain kernel features that are needed for USB audio. These are usually cheap 'Chinese' tablets, but also the Samsung Note 1 and Galaxy S2 lack it. When your device has a Rockchip cpu inside, chances are very high it will not work. Basic rule of thumb is that if your Android tablet is under 200 euro, it probably is not going to work.
  • Power: some USB audio devices require a lot of current to run. Most Android devices do not supply more than 100mA, so sometimes you will need a powered USB hub in between to function properly. Note that sometimes, the device is detected without a powered hub, but problems start to appear when starting recording.

Android processor/chipset limitations

Not all Android devices are capable of performing simultaneous full-duplex 24-bit recording and playback or multichannel recording. In USB Audio Recorder PRO, all Android devices tested did not have issues with 24-bit recording or playback, but as soon as simultaneous recording and playback was tested in Audio Evolution Mobile, some devices failed to record or playback or caused heavy noises.

It is our believe that this limitation is directly related to the chipset used in the Android device. That does not mean that the chipset is at fault, but perhaps the kernel or USB host controller driver was not set up correctly to handle isochronous audio streams. Since USB audio was never tested on these devices, it was probably never noticed. Our test results show the following:

  • Qualcomm processors (XPeria S, XPeria Z) are the best: simultaneous 24-bit recording and playback, 18-channel 24-bit recording no problem.
  • Samsung Exynos: probably same as Qualcomm (Galaxy S3 and S4 should do fine)
  • NVidia Tegra 3: simultaneous 16-bit recording and playback ok, some devices (Acer A511) do full duplex 24-bit, some don't (Asus TF300).
  • NVidia Tegra 2: simultaneous 16-bit recording and playback ok, 24-bit not ok.
  • OMAP processors (Nexus S, Samsung Galaxy Tab 2) : cause heavy drop-outs, unusable

This is why Audio Evolution Mobile will default to 16-bit input and output when your device supports both 16- and 24-bit modes. You can of course change these manually to try with your Android device.

Note: we kindly request your input! Please let us know by email which Android/USB audio device combination works with 16 and/or 24-bit so we can get a better understanding of what works or not. Our email address is info@audio-evolution.com.

Using USB audio interfaces with Audio Evolution Mobile

In order to use USB audio interfaces with Audio Evolution Mobile you will need to do an in-app purchase or purchase USB Audio Recorder PRO.

Connect your USB audio interface first, then start Audio Evolution Mobile. The device status dialog that appears after starting the app will display whether a USB audio device is detected and if the add-on is licensed. Note that device detection will not automatically mean that it will also work correctly! Some Android devices do not support the required isochronous mode to record and playback audio data, but will get detected just fine. Make sure to do a couple of test recordings before purchase. You can also use the demo version of Audio Evolution Mobile to do some tests since that allows you to record up to 2 minutes.

After the device is detected, the app will verify if your audio device has inputs and/or outputs. For instance, if you have a USB mic without headphones output, it will configure itself to record from USB and playback through the Android's speaker or headphones. When both inputs and outputs are found, all audio of Audio Evolution Mobile will be routed through the USB audio device. Note that all other audio of your Android device like system sounds or audio from other music players is not affected and will not play through the USB audio device.

From here on, you can simply use the app as you are used to, but we advise you to reset the 'Latency correction' option in the Preferences to 0 if you have something entered there.

Troubleshooting

First of all, make sure your USB audio device works correctly with USB Audio Recorder PRO. See the Troubleshooting section on the USB Audio Recorder PRO website first. If it doesn't work there, chances are very low that it will work in Audio Evolution Mobile.

Changing input mode, sample rate etc.

When you like to change input resolution, sample rate, wish to select a different input when your device has several inputs or when you want to record only channel of a stereo input, you need to open the Input selection dialog. At the bottom of each mixer channel, you will see two or more circles:

These represent the mixer channel 'pages'. Since not everything will fit on your screen, the mixer controls for one channel are divided onto several pages. Slide your finger over the circles to switch between these pages: the filled circle will represent the current page. Now, slide all the way to the right so that the right-most circle will be light-grey:

The top button on the mixer channel will show an input sign and an input name. Tap on it once to open the Input selection dialog:

In the Input selection dialog you can choose:

  • Input device: Android or USB
  • Sample rate: depends on the rates available of the selected Input device
  • Bit resolution: can be 16, 24 or 32 bit, but depends on the audio device and sometimes on the sample rate used.
  • Audio mode: some USB audio device have multiple audio modes. For example for selecting different inputs, mono, stereo etc.
  • Audio channel: for a stereo mode for example, you can choose to record in stereo (1-2) or mono (either 1 or 2). If you have a multitrack mode with 18 channels, you could select stereo pairs 1-2, 3-4, 5-6, and so on or mono channel 1-18. Note: when a track already has one or more stereo samples, you cannot select a mono mode and vice versa.

You can choose a different input mode for each channel, but only one can be armed at a time.

Changing output mode

Similar to input, you can also change your USB audio output settings by switching to the master mixer screen: press the top-right button twice to go from the time line area to the master mixer screen. There you will see the Master bus on the left. Just as with the inputs, slide to the last mixer channel page (using the circles) and press the top button called Output.

You can switch the output between USB and Android. Note that when you combine an Android output with a USB input, latency issues may appear, just as when you would only use Android input and outputs.

Hardware mixer screen

When your USB audio interface exposes internal controls such as input gain and volume, they will be presented on the Hardware mixer screen. Tap the top-right icon three times to arrive at the hardware mixer screen:

If you do not see this screen and you arrive back on the time line screen, your device does not expose any controls and you will need to adjust settings using the physical knobs on your device, when available.

There can be many controls: if they do not fit on the screen, you can swipe the controls by sliding your finger left-right at the bottom texts of the controls.

There are three types of controls:

  • Out vol: controls output volume
  • Gain: controls input gain
  • Mon: controls zero-latency monitoring: the amount of input signal that is fed directly to the output to hear yourself playing/singing.

We will improve this screen in later versions to display the control's values.

Note that the controls have a number assigned to them. This is an internal number that doesn't mean a lot, but just consider that controls that have the same number belong to each other and control the same 'unit of functionality'. For example, in the picture above, there are two functional units 10 and 11. 10 controls output volume, but is split into three controls: a master, left and right control. Unit 11 control input gain and is split in the same way.

When you open the menu and select Preferences, slide to the bottom of the Preferences page to display the USB audio related options.

Buffer size: we recommend to leave it on 4096 frames. For audio-only, it doesn't really make sense to lower this value since latency is corrected automatically for a large part.

Force one packet per transfer: only experiment with this if your device is not recording or playing back properly.

Always record and playback: some devices like the Digitech RP255 can only function properly when doing simultaneous recording and playback, even if the device only needs to play. Do not enable unless you cannot record or playback.

Latency correction

Although latency is much lower than using the Android audio system and automatic latency compensation takes place, there can be a small latency left-over. Please use the method described here to correct for this small latency if you want to. Make sure to reset the 'Latency correction' option from the Preferences to 0 first!

usbaudiosupport.txt · Last modified: 2016/08/30 12:01 (external edit)