All audio modulators: input from "mic" is seriously distorted

[f4exb]

This applies to all audio modulators that is as of now: AM, NFM, WFM, SSB/DSB

The input from the sound input device (turned on with the "mic" icon button) is very very distorted. It looks like the waveform is modulated (when looking at the enveloppe in AM for example). This may indicate a problem with the interfacing with the QAudioDevice in AudioInput class. The bytes seems not to be put in the correct order.

Using the same mic device and recording to a file played back in the modulator gives a correct audio. So it is not an issue with the mic.

[f4exb]

Noticed a few things:

• with the file sink it seems to work normally no just select base sample rate to 96 kS/a or higher and there is the same problem as with real Tx devices
• with the LimeSDR it works only when the channel sample rate is lower than 96 kS/s (twice the audio sample rate). This seems to indicate some problem with the interpolation using real devices

[f4exb]

In the modulators pullAudio overloaded virtual method:

unsigned int nbSamplesAudio = nbSamples * m_interpolatorDistance;

m_interpolatorDistance is calculated as the audio rate (48000) divided by the desired sample rate BEFORE integer interpolation. So this does not take into account the integer interpolation. This method is called only when pulling audio from the input source.

[f4exb]

Yes thatś it. A quick test with a baseband sample rate of 100 kS/s and factor hard divided by 2 gives correct audio. The problem is to get the baseband sample rate at channel plogin level.

[f4exb]

Fixed with v3.5.4