Discontinuity glitches on Realtek (and any exclusive mic)

Environment:

• OS: Windows 11
• miniaudio 0.11.24
• Backend: WASAPI (Exclusive Mode, Capture)
• Format: Tested on Realtek & M-Audio duo interface (2-channel, 48kHz, s16)

Description

When running a capture device in exclusive mode (ma_share_mode_exclusive), the captured audio runs ~1.44x faster than wall-clock time, and individual periods (e.g., 30ms / 1440 frames) appear duplicated in the captured buffer.

In addition, AUDCLNT_BUFFERFLAGS_DATA_DISCONTINUITY is triggered on almost every packet (~50/sec) during pure capture.

Shared mode capture on the same hardware and period size works as expected with no duplication or glitches.

Suspected Root Causes

1. Double GetBuffer per event in ma_device_read__wasapi(): In WASAPI event-driven exclusive mode, the event fires once per ready packet. Inside ma_device_read__wasapi(), the inner loop calls GetBuffer -> ReleaseBuffer and immediately attempts another GetBuffer before waiting on the event again. This appears to consume the subsequent packet prematurely, resulting in 2 packets read per 1 wait event and duplicating audio frames.

2. Discontinuity handling missing for pure capture: The exclusive-mode recovery path for buffer discontinuities seems to only be applied to duplex configurations, leaving pure capture streams continuously flagging DATA_DISCONTINUITY once an overrun occurs.

Minimal Reproducible Example

#define MINIAUDIO_IMPLEMENTATION
#include "miniaudio.h"
#include <stdio.h>

void data_callback(ma_device* pDevice, void* pOutput, const void* pInput, ma_uint32 frameCount) {
    // Inspect pInput: identical frame blocks repeat every period.
    (void)pOutput;
    (void)pDevice;
    (void)frameCount;
}

int main() {
    ma_device_config config = ma_device_config_init(ma_device_type_capture);
    config.capture.shareMode = ma_share_mode_exclusive;
    config.capture.format    = ma_format_unknown; // Native format
    config.dataCallback      = data_callback;
    
    // e.g. 10ms - 30ms periods
    config.periodSizeInMilliseconds = 10; 

    ma_device device;
    if (ma_device_init(NULL, &config, &device) != MA_SUCCESS) {
        printf("Failed to init capture device.\n");
        return -1;
    }

    ma_device_start(&device);
    printf("Capturing... Press Enter to stop.\n");
    getchar();

    ma_device_uninit(&device);
    return 0;
}