v5 ReSID resampling broken, fill level hits periodically zero

[mithrendal]

https://csdb.dk/release/?id=241359

on resampling

the fill level of audio buffer runs periodically to zero

resulting stuttering sound with crackling noises

sound works fine on setting fast and interpolate

also affects https://vc64web.github.io

[mithrendal]

ReSID resampling works fine when switching back to a v4.5 emulation core

I did some more tests on ReSID resampling mode

findings

1. the ReSID resampling in v5 draws more computing power. When using Macbook M1 solely on battery, energy saving measurements seems to kick in. With these measurements it is not able to sufficiently compute sound samples, vAmiga.app activity hits 100%. Resulting in audio buffer underruns... fill level drops periodically to 0. When on power line again vAmiga.app activity drops to 67%, fill level stable.

2. there is a constantly crackling noise which does not come from buffer underruns. It is just there.

[dirkwhoffmann]

Culpript for the cracking noise is commit 2ce74bc

[dirkwhoffmann]

The crackling noise was caused by this function:

void
ReSID::setClockFrequency(u32 frequency)
{
    if (clockFrequency != frequency) {

        clockFrequency = frequency;
        sid->set_sampling_parameters((double)clockFrequency,
                                     (reSID::sampling_method)samplingMethod,
                                     (double)sampleRate);
        trace(SID_DEBUG, "Setting clock frequency to %d\n", frequency);
    }

    assert((u32)sid->clock_frequency == clockFrequency);
}

In the faulty implementation, the line

     if (clockFrequency != frequency) {

was missing. As a result, reSID got reinitialized in every frame.

[mithrendal]

merged latest commits into vc64web. You fixed the issue. ✌️