Project Sample Rate

All digital audio is defined by samples, or snapshots, of information (data) which are used to capture, describe and reproduce the equivalent analog sound. The speed at which these samples are captured and played back is called the sample rate. Each sample contains bits (binary digits - 1 or 0) which are used to describe the individual samples.The number of bits used per sample is known as the bit depth. The greater the number of bits used to describe each sample and the greater the number of samples per second, the greater the precision and fidelity to the analog sound achievable. So, all digital audio has a sample rate and a bit depth. For example, digital audio on a CD uses a sample rate of 44.1kHz with a bit depth of 16-bit, meaning 44,100 samples per second and each sample is made up of 16 bits (i.e. each sample is a string of 16 ones and zeros).

As digital technology has progressed, greater sample rates and higher bit depths have become possible. The sample rates available on mobile devices are usually 44100 or 48000Hz, but when using certain USB audio interfaces, higher sample rates can be achieved.

Contrary to desktop systems, mobile devices have one 'native' sample rate, chosen by the manufacturer. Only by using this 'native' sample rate, the lowest latency can be achieved. By default, Audio Evolution Mobile uses your device's native sample rate for new projects, which will almost certainly be 48kHz these days. You can choose a different sample rate, but the device will apply resampling on the input and output, causing higher latency and a bit of quality loss.

The native sample rate allows for the lowest latency, but this also results in the highest CPU load since Android will use lower buffer sizes in this case. For this reason, Audio Evolution Mobile's default project setting is to use the Oboe/AAudio system with the device's native sample rate and a buffer size that is 2 times larger than the lowest buffer size, reducing the CPU load a bit.

It is also worth considering whether you are planning to export your Audio Evolution Mobile tracks as stems to import into other software. Though resampling is usually possible, if you are planning to take your exported stems elsewhere, and you know what sample rate you will be using there, it certainly can't do any harm to plan ahead and use this same sample rate for your Audio Evolution Mobile project.

To set your project sample rate, press the Project button on the Arranger Screen. This opens the Project Options panel shown below. At the bottom of the options, Sample Rate can be selected from where you can choose from the available options.

NOTE. The project sample rate becomes fixed as soon as any audio clip is present in the project. If you set your project sample rate and the first thing you do afterwards is import an audio clip with a different sample rate into a project without any audio clips, you will be given the chance to either resample the audio clip  to the project sample rate as it is imported, or import the audio clip with its original sample rate: this second option will change the project sample rate to match the imported clip and, with the audio clip now present, the project sample rate now becomes fixed.