webcam_mediafoundation.c

Go to the documentation of this file.

 
#ifdef _WIN32
 
#define COBJMACROS
#include <ascii-chat/video/webcam/webcam.h>
#include <ascii-chat/common.h>
#include <ascii-chat/util/time.h>
#include <ascii-chat/util/overflow.h>
#include <ascii-chat/platform/system.h>
#include <mfapi.h>
#include <mfidl.h>
#include <mfreadwrite.h>
#include <mferror.h>
 
// Windows Media Foundation webcam implementation
// Note: MF_SOURCE_READER_ENABLE_ADVANCED_VIDEO_PROCESSING and
//       MF_SOURCE_READER_ENABLE_VIDEO_PROCESSING are defined in mfreadwrite.h
 
struct webcam_context_t {
  IMFMediaSource *device;
  IMFSourceReader *reader;
  int width;
  int height;
  BOOL mf_initialized;
  BOOL com_initialized;
  image_t *cached_frame; // Reusable frame buffer (allocated once, reused for each read)
};
 
static HRESULT enumerate_devices_and_print(void) {
  IMFAttributes *attr = NULL;
  IMFActivate **devices = NULL;
  UINT32 count = 0;
  HRESULT hr;
 
  // Create attribute store for device enumeration
  hr = MFCreateAttributes(&attr, 1);
  if (FAILED(hr)) {
    return SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to create MF attributes: 0x%08x", hr);
  }
 
  // Set the device type to video capture
  hr =
      IMFAttributes_SetGUID(attr, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID);
  if (FAILED(hr)) {
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to set MF device type: 0x%08x", hr);
    goto cleanup;
  }
 
  // Enumerate video capture devices
  hr = MFEnumDeviceSources(attr, &devices, &count);
  if (FAILED(hr)) {
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to enumerate MF devices: 0x%08x", hr);
    goto cleanup;
  }
 
  log_info("Found %d video capture device(s):", count);
  for (UINT32 i = 0; i < count; i++) {
    LPWSTR friendlyName = NULL;
    UINT32 nameLength = 0;
 
    hr = IMFActivate_GetAllocatedString(devices[i], &MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME, &friendlyName, &nameLength);
    if (SUCCEEDED(hr) && friendlyName) {
      // Convert wide string to multibyte for logging
      int len = WideCharToMultiByte(CP_UTF8, 0, friendlyName, -1, NULL, 0, NULL, NULL);
      if (len > 0) {
        char *mbName = SAFE_MALLOC((size_t)len, void *);
        if (mbName && WideCharToMultiByte(CP_UTF8, 0, friendlyName, -1, mbName, len, NULL, NULL)) {
          log_info("  Device %d: %s", i, mbName);
        }
        SAFE_FREE(mbName);
      }
      CoTaskMemFree(friendlyName);
    } else {
      log_info("  Device %d: <Unknown Name>", i);
    }
  }
 
cleanup:
  if (devices) {
    for (UINT32 i = 0; i < count; i++) {
      if (devices[i]) {
        IMFActivate_Release(devices[i]);
      }
    }
    CoTaskMemFree((void *)devices);
  }
  if (attr) {
    IMFAttributes_Release(attr);
  }
 
  return hr;
}
 
asciichat_error_t webcam_init_context(webcam_context_t **ctx, unsigned short int device_index) {
  log_info("Opening Windows webcam with Media Foundation, device index %d", device_index);
 
  webcam_context_t *cam;
  cam = SAFE_MALLOC(sizeof(webcam_context_t), webcam_context_t *);
 
  // Initialize all fields
  cam->device = NULL;
  cam->reader = NULL;
  cam->width = 0;
  cam->height = 0;
  cam->mf_initialized = FALSE;
  cam->com_initialized = FALSE;
  cam->cached_frame = NULL;
 
  HRESULT hr;
  IMFAttributes *attr = NULL;
  IMFActivate **devices = NULL;
  UINT32 count = 0;
  int result = -1;
 
  // Suppress Windows Media Foundation's verbose initialization output
  platform_stderr_redirect_handle_t stderr_handle = platform_stderr_redirect_to_null();
 
  // Initialize COM
  hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
  if (SUCCEEDED(hr)) {
    cam->com_initialized = TRUE;
  } else if (hr != RPC_E_CHANGED_MODE) {
    platform_stderr_restore(stderr_handle);
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to initialize COM: 0x%08x", hr);
    goto error;
  }
 
  // Initialize Media Foundation
  hr = MFStartup(MF_VERSION, MFSTARTUP_NOSOCKET);
  if (FAILED(hr)) {
    platform_stderr_restore(stderr_handle);
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to startup Media Foundation: 0x%08x", hr);
    goto error;
  }
  cam->mf_initialized = TRUE;
 
  platform_stderr_restore(stderr_handle);
 
  // Enumerate and print all devices
  enumerate_devices_and_print();
 
  // Create attribute store for device enumeration
  hr = MFCreateAttributes(&attr, 1);
  if (FAILED(hr)) {
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to create MF attributes: 0x%08x", hr);
    goto error;
  }
 
  hr =
      IMFAttributes_SetGUID(attr, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID);
  if (FAILED(hr)) {
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to set MF device type: 0x%08x", hr);
    goto error;
  }
 
  // Enumerate devices
  hr = MFEnumDeviceSources(attr, &devices, &count);
  if (FAILED(hr)) {
    SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to enumerate MF devices: 0x%08x", hr);
    goto error;
  }
 
  if (count == 0) {
    SET_ERRNO(ERROR_WEBCAM, "No video capture devices found");
    hr = E_FAIL;
    goto error;
  }
 
  if (device_index >= count) {
    SET_ERRNO(ERROR_WEBCAM, "Device index %d out of range (0-%d)", device_index, count - 1);
    hr = E_FAIL;
    goto error;
  }
 
  // Create media source for the specified device
  hr = IMFActivate_ActivateObject(devices[device_index], &IID_IMFMediaSource, (void **)&cam->device);
  log_info("IMFActivate_ActivateObject returned: 0x%08x", hr);
 
  if (FAILED(hr)) {
    log_error("CRITICAL: Failed to activate MF device: 0x%08x", hr);
    log_error("  0x80070005 = E_ACCESSDENIED (device in use)");
    log_error("  0xc00d3704 = Device already in use");
    log_error("  0xc00d3e85 = MF_E_VIDEO_RECORDING_DEVICE_INVALIDATED");
    result = SET_ERRNO(ERROR_WEBCAM_IN_USE, "Media Foundation device %d is in use (HRESULT: 0x%08x)", device_index, hr);
    goto error;
  }
 
  // Create source reader with GPU-accelerated video processing (Windows 8+)
  // This enables automatic YUV->RGB conversion with hardware acceleration
  IMFAttributes *readerAttrs = NULL;
  hr = MFCreateAttributes(&readerAttrs, 1);
  if (FAILED(hr)) {
    log_error("Failed to create reader attributes: 0x%08x", hr);
    result =
        SET_ERRNO(ERROR_WEBCAM, "Failed to create reader attributes for device %d (HRESULT: 0x%08x)", device_index, hr);
    goto error;
  }
 
  // Enable advanced video processing for GPU-accelerated YUV->RGB conversion (Windows 8+)
  // This is the recommended attribute for webcam capture with format conversion
  hr = IMFAttributes_SetUINT32(readerAttrs, &MF_SOURCE_READER_ENABLE_ADVANCED_VIDEO_PROCESSING, TRUE);
  if (FAILED(hr)) {
    log_warn("Failed to set advanced video processing attribute: 0x%08x", hr);
  }
 
  hr = MFCreateSourceReaderFromMediaSource(cam->device, readerAttrs, &cam->reader);
  log_info("MFCreateSourceReaderFromMediaSource returned: 0x%08x, readerAttrs=%p", hr, (void *)readerAttrs);
 
  if (readerAttrs) {
    IMFAttributes_Release(readerAttrs);
  }
 
  if (FAILED(hr)) {
    log_error("CRITICAL: Failed to create MF source reader: 0x%08x", hr);
    result =
        SET_ERRNO(ERROR_WEBCAM_IN_USE,
                  "Failed to create Media Foundation source reader for device %d (HRESULT: 0x%08x)", device_index, hr);
    goto error;
  }
 
  // IMPORTANT: Select the video stream first before configuring
  hr = IMFSourceReader_SetStreamSelection(cam->reader, (DWORD)MF_SOURCE_READER_ALL_STREAMS, FALSE);
  log_info("SetStreamSelection (deselect all) returned: 0x%08x", hr);
  if (FAILED(hr)) {
    log_warn("Failed to deselect all streams: 0x%08x", hr);
  }
 
  hr = IMFSourceReader_SetStreamSelection(cam->reader, (DWORD)MF_SOURCE_READER_FIRST_VIDEO_STREAM, TRUE);
  log_info("SetStreamSelection (select video) returned: 0x%08x", hr);
  if (FAILED(hr)) {
    log_error("Failed to select video stream: 0x%08x", hr);
    result = SET_ERRNO(ERROR_WEBCAM, "Failed to select video stream for device %d (HRESULT: 0x%08x)", device_index, hr);
    goto error;
  }
 
  // Request RGB32 output format (BGRA) at 640x480 resolution
  // Combined with MF_SOURCE_READER_ENABLE_ADVANCED_VIDEO_PROCESSING, this enables
  // GPU-accelerated YUV->RGB conversion
  IMFMediaType *rgbType = NULL;
  hr = MFCreateMediaType(&rgbType);
  if (SUCCEEDED(hr)) {
    IMFMediaType_SetGUID(rgbType, &MF_MT_MAJOR_TYPE, &MFMediaType_Video);
    IMFMediaType_SetGUID(rgbType, &MF_MT_SUBTYPE, &MFVideoFormat_RGB32);
 
    // Request 640x480 resolution (we only need 480x270 max for ascii-chat)
    // This dramatically reduces pixel copy overhead (307,200 vs 8,294,400 pixels)
    UINT64 frameSize = ((UINT64)640 << 32) | (UINT64)480;
    hr = IMFMediaType_SetUINT64(rgbType, &MF_MT_FRAME_SIZE, frameSize);
    if (FAILED(hr)) {
      log_warn("Could not set frame size to 640x480: 0x%08x", hr);
    }
 
    // Use partial type - let MF fill in other details
    hr = IMFSourceReader_SetCurrentMediaType(cam->reader, (DWORD)MF_SOURCE_READER_FIRST_VIDEO_STREAM, NULL, rgbType);
    IMFMediaType_Release(rgbType);
 
    if (SUCCEEDED(hr)) {
      log_info("Successfully requested RGB32 output format at 640x480");
    } else {
      log_warn("Could not set RGB32 format: 0x%08x, will use native format", hr);
      // Don't fail - just use whatever format the camera provides
    }
  }
 
  // Get actual media type and dimensions
  IMFMediaType *currentType = NULL;
  hr = IMFSourceReader_GetCurrentMediaType(cam->reader, (DWORD)MF_SOURCE_READER_FIRST_VIDEO_STREAM, &currentType);
  if (SUCCEEDED(hr)) {
    UINT64 frameSize = 0;
    hr = IMFMediaType_GetUINT64(currentType, &MF_MT_FRAME_SIZE, &frameSize);
    if (SUCCEEDED(hr)) {
      cam->width = (int)(frameSize >> 32);
      cam->height = (int)(frameSize & 0xFFFFFFFF);
      log_info("Media Foundation webcam opened: %dx%d", cam->width, cam->height);
    } else {
      // Default resolution if we can't get the actual size
      cam->width = 640;
      cam->height = 480;
      log_warn("Could not get frame size, using default 640x480");
    }
    IMFMediaType_Release(currentType);
  } else {
    cam->width = 640;
    cam->height = 480;
    log_warn("Could not get media type, using default 640x480");
  }
 
  DWORD streamIndex, flags;
  LONGLONG timestamp;
  IMFSample *sample = NULL;
 
  hr = IMFSourceReader_ReadSample(cam->reader, (DWORD)MF_SOURCE_READER_FIRST_VIDEO_STREAM,
                                  0, // Regular synchronous read
                                  &streamIndex, &flags, &timestamp, &sample);
 
  if (FAILED(hr)) {
    log_error("CRITICAL: Failed to read test frame during initialization: 0x%08x", hr);
    result =
        SET_ERRNO(ERROR_WEBCAM_IN_USE, "Failed to read test frame from device %d (HRESULT: 0x%08x)", device_index, hr);
    goto error;
  }
 
  // Clean up the test sample if we got one
  if (sample) {
    IMFSample_Release(sample);
  }
 
  // Cleanup enumeration resources on success
  if (devices) {
    for (UINT32 i = 0; i < count; i++) {
      if (devices[i]) {
        IMFActivate_Release(devices[i]);
      }
    }
    CoTaskMemFree((void *)devices);
    devices = NULL;
  }
  if (attr) {
    IMFAttributes_Release(attr);
    attr = NULL;
  }
 
  *ctx = cam;
  return ASCIICHAT_OK;
 
error:
  // Only cleanup devices and attr if they haven't been cleaned up yet
  if (devices) {
    for (UINT32 i = 0; i < count; i++) {
      if (devices[i]) {
        IMFActivate_Release(devices[i]);
      }
    }
    CoTaskMemFree((void *)devices);
  }
  if (attr) {
    IMFAttributes_Release(attr);
  }
  if (cam->reader) {
    IMFSourceReader_Release(cam->reader);
  }
  if (cam->device) {
    IMFMediaSource_Release(cam->device);
  }
  if (cam->mf_initialized) {
    MFShutdown();
  }
  if (cam->com_initialized) {
    CoUninitialize();
  }
  if (cam) {
    SAFE_FREE(cam);
  }
  return result;
}
 
void webcam_flush_context(webcam_context_t *ctx) {
  if (ctx && ctx->reader) {
    // Flush to cancel any pending ReadSample operations
    // This interrupts blocking synchronous reads in other threads
    HRESULT hr = IMFSourceReader_Flush(ctx->reader, (DWORD)MF_SOURCE_READER_ALL_STREAMS);
    if (FAILED(hr)) {
      log_warn("IMFSourceReader_Flush failed: 0x%08lx", hr);
    } else {
      log_debug("Flushed webcam source reader");
    }
  }
}
 
void webcam_cleanup_context(webcam_context_t *ctx) {
  if (ctx) {
    if (ctx->reader) {
      // Flush before release to ensure no pending operations
      webcam_flush_context(ctx);
      IMFSourceReader_Release(ctx->reader);
      ctx->reader = NULL;
    }
    if (ctx->device) {
      IMFMediaSource_Release(ctx->device);
      ctx->device = NULL;
    }
    if (ctx->mf_initialized) {
      MFShutdown();
      ctx->mf_initialized = FALSE;
    }
    if (ctx->com_initialized) {
      CoUninitialize();
      ctx->com_initialized = FALSE;
    }
    // Free cached frame if it was allocated
    if (ctx->cached_frame) {
      image_destroy(ctx->cached_frame);
      ctx->cached_frame = NULL;
    }
    SAFE_FREE(ctx);
    log_debug("Windows Media Foundation webcam closed");
  }
}
 
image_t *webcam_read_context(webcam_context_t *ctx) {
  if (!ctx || !ctx->reader) {
    return NULL;
  }
 
  HRESULT hr;
  IMFSample *sample = NULL;
  DWORD streamIndex, flags;
  LONGLONG timestamp;
 
  // Timing diagnostic: measure ReadSample duration
  LARGE_INTEGER freq, start, end;
  QueryPerformanceFrequency(&freq);
  QueryPerformanceCounter(&start);
 
  // Read a sample from the source reader
  // Use 0 for synchronous blocking read (DRAIN flag was wrong - that's for EOF)
  hr = IMFSourceReader_ReadSample(ctx->reader, (DWORD)MF_SOURCE_READER_FIRST_VIDEO_STREAM,
                                  0, // Regular synchronous read
                                  &streamIndex, &flags, &timestamp, &sample);
 
  QueryPerformanceCounter(&end);
  double elapsed_ms = ((double)(end.QuadPart - start.QuadPart)) * 1000.0 / (double)freq.QuadPart;
 
  char duration_str[32];
  format_duration_ms(elapsed_ms, duration_str, sizeof(duration_str));
  log_info("ReadSample took %s (hr=0x%08x, flags=0x%08x, sample=%p)", duration_str, hr, flags, sample);
 
  // Check for stream tick or other non-data flags
  if (SUCCEEDED(hr) && (flags & MF_SOURCE_READERF_STREAMTICK)) {
    log_info("Received stream tick, no sample yet");
    return NULL;
  }
 
  if (SUCCEEDED(hr) && (flags & MF_SOURCE_READERF_ENDOFSTREAM)) {
    log_warn("End of stream reached");
    return NULL;
  }
 
  if (FAILED(hr)) {
    log_error("CRITICAL: Failed to read MF sample on FIRST attempt: 0x%08x", hr);
    log_error("  0x80070005 = E_ACCESSDENIED (device in use)");
    log_error("  0xc00d3704 = Device already in use");
    log_error("  0xc00d3e85 = MF_E_VIDEO_RECORDING_DEVICE_INVALIDATED");
    log_error("  0x80004005 = E_FAIL (generic failure)");
    log_error("  0xc00d36b2 = MF_E_INVALIDREQUEST");
    log_error("  0xc00d36c4 = MF_E_HW_MFT_FAILED_START_STREAMING");
 
    // Return NULL - device is likely in use
    return NULL;
  }
 
  if (!sample) {
    static int null_count = 0;
    null_count++;
    if (null_count <= 10) {
      // This is normal when using DRAIN flag - it means no sample ready yet
      if (null_count == 1) {
        log_info("No sample available yet (this is normal during startup)");
      }
    } else if (null_count > 50) {
      // Too many consecutive NULL samples - likely exclusive access issue
      log_error("Too many consecutive NULL samples (%d) - device likely in use", null_count);
    }
    return NULL;
  }
 
  // Get the media buffer from the sample
  IMFMediaBuffer *buffer = NULL;
  hr = IMFSample_ConvertToContiguousBuffer(sample, &buffer);
  if (FAILED(hr)) {
    static int buffer_fail_count = 0;
    buffer_fail_count++;
    log_debug("Failed to get contiguous buffer: 0x%08x (failure #%d)", hr, buffer_fail_count);
 
    if (buffer_fail_count > 20) {
      log_error("CRITICAL: Failed to get media buffer %d times - webcam likely in use", buffer_fail_count);
    }
 
    IMFSample_Release(sample);
    return NULL;
  }
 
  // Lock the buffer and get the data
  BYTE *bufferData = NULL;
  DWORD bufferLength = 0;
  hr = IMFMediaBuffer_Lock(buffer, &bufferData, NULL, &bufferLength);
  if (FAILED(hr)) {
    static int lock_fail_count = 0;
    lock_fail_count++;
    log_debug("Failed to lock MF buffer: 0x%08x (failure #%d)", hr, lock_fail_count);
 
    if (lock_fail_count > 20) {
      log_error("CRITICAL: Failed to lock media buffer %d times - webcam likely in use", lock_fail_count);
    }
 
    IMFMediaBuffer_Release(buffer);
    IMFSample_Release(sample);
    return NULL;
  }
 
  // Use cached frame dimensions from context (no need to query media type every frame)
  UINT32 width = (UINT32)ctx->width;
  UINT32 height = (UINT32)ctx->height;
 
  // Check for integer overflow before multiplication (prevents heap corruption).
  // Check pixel count overflow
  size_t pixel_count_check = 0;
  if (checked_size_mul((size_t)width, (size_t)height, &pixel_count_check) != ASCIICHAT_OK) {
    log_error("webcam_read_context: dimensions overflow: %u x %u", width, height);
    IMFMediaBuffer_Unlock(buffer);
    IMFMediaBuffer_Release(buffer);
    IMFSample_Release(sample);
    return NULL;
  }
 
  // Check pixel buffer size overflow
  size_t pixel_buffer_size = 0;
  if (checked_size_mul(pixel_count_check, sizeof(rgb_pixel_t), &pixel_buffer_size) != ASCIICHAT_OK) {
    log_error("webcam_read_context: pixel buffer overflow: %zu pixels", pixel_count_check);
    IMFMediaBuffer_Unlock(buffer);
    IMFMediaBuffer_Release(buffer);
    IMFSample_Release(sample);
    return NULL;
  }
 
  // Allocate or reuse cached frame (allocated once, reused for each call)
  // This matches the documented API contract: "Subsequent calls reuse the same buffer"
  if (!ctx->cached_frame || ctx->cached_frame->w != (int)width || ctx->cached_frame->h != (int)height) {
    // Free old cached frame if it exists with different dimensions
    if (ctx->cached_frame) {
      image_destroy(ctx->cached_frame);
    }
 
    // Create new image_t structure
    image_t *img = SAFE_MALLOC(sizeof(image_t), image_t *);
    img->w = (int)(unsigned int)width;
    img->h = (int)(unsigned int)height;
    // Use SIMD-aligned allocation for optimal NEON/AVX performance with vld3q_u8
    img->pixels = SAFE_MALLOC_SIMD(pixel_buffer_size, rgb_pixel_t *);
    ctx->cached_frame = img;
  }
 
  image_t *img = ctx->cached_frame;
 
  // Copy RGB32 data (BGRA order in Media Foundation)
  // Media Foundation converts YUV->RGB32 via GPU-accelerated pipeline
  // RGB32 format is 4 bytes per pixel: B, G, R, A (we ignore alpha)
 
  LARGE_INTEGER copy_start, copy_end;
  QueryPerformanceCounter(&copy_start);
 
  UINT32 pixel_count = width * height;
  BYTE *src = bufferData;
  rgb_pixel_t *dst = img->pixels;
 
  // Optimized pixel copy - process 4 pixels at a time
  UINT32 i;
  for (i = 0; i + 4 <= pixel_count; i += 4) {
    // Pixel 0
    dst[0].b = src[0];
    dst[0].g = src[1];
    dst[0].r = src[2];
    // Pixel 1
    dst[1].b = src[4];
    dst[1].g = src[5];
    dst[1].r = src[6];
    // Pixel 2
    dst[2].b = src[8];
    dst[2].g = src[9];
    dst[2].r = src[10];
    // Pixel 3
    dst[3].b = src[12];
    dst[3].g = src[13];
    dst[3].r = src[14];
 
    src += 16; // 4 pixels * 4 bytes
    dst += 4;
  }
 
  // Handle remaining pixels
  for (; i < pixel_count; i++) {
    dst->b = src[0];
    dst->g = src[1];
    dst->r = src[2];
    src += 4;
    dst++;
  }
 
  QueryPerformanceCounter(&copy_end);
  double copy_ms = ((double)(copy_end.QuadPart - copy_start.QuadPart)) * 1000.0 / (double)freq.QuadPart;
 
  char copy_duration_str[32];
  format_duration_ms(copy_ms, copy_duration_str, sizeof(copy_duration_str));
  log_info("Pixel copy took %s (%u pixels)", copy_duration_str, pixel_count);
 
  // Unlock and cleanup
  IMFMediaBuffer_Unlock(buffer);
  IMFMediaBuffer_Release(buffer);
  IMFSample_Release(sample);
 
  return img;
}
 
asciichat_error_t webcam_get_dimensions(webcam_context_t *ctx, int *width, int *height) {
  if (!ctx || !width || !height) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "webcam_get_dimensions: invalid parameters");
  }
 
  *width = ctx->width;
  *height = ctx->height;
  return ASCIICHAT_OK;
}
 
asciichat_error_t webcam_list_devices(webcam_device_info_t **out_devices, unsigned int *out_count) {
  if (!out_devices || !out_count) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "webcam_list_devices: invalid parameters");
  }
 
  *out_devices = NULL;
  *out_count = 0;
 
  IMFAttributes *attr = NULL;
  IMFActivate **mf_devices = NULL;
  UINT32 mf_count = 0;
  HRESULT hr;
  asciichat_error_t result = ASCIICHAT_OK;
  BOOL com_initialized = FALSE;
  BOOL mf_initialized = FALSE;
 
  // Suppress Windows Media Foundation's verbose initialization output
  platform_stderr_redirect_handle_t stderr_handle = platform_stderr_redirect_to_null();
 
  // Initialize COM
  hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
  if (SUCCEEDED(hr)) {
    com_initialized = TRUE;
  } else if (hr != RPC_E_CHANGED_MODE) {
    platform_stderr_restore(stderr_handle);
    return SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to initialize COM: 0x%08x", hr);
  }
 
  // Initialize Media Foundation
  hr = MFStartup(MF_VERSION, MFSTARTUP_NOSOCKET);
  if (FAILED(hr)) {
    platform_stderr_restore(stderr_handle);
    result = SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to startup Media Foundation: 0x%08x", hr);
    goto cleanup;
  }
  mf_initialized = TRUE;
 
  platform_stderr_restore(stderr_handle);
 
  // Create attribute store for device enumeration
  hr = MFCreateAttributes(&attr, 1);
  if (FAILED(hr)) {
    result = SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to create MF attributes: 0x%08x", hr);
    goto cleanup;
  }
 
  // Set the device type to video capture
  hr =
      IMFAttributes_SetGUID(attr, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE, &MF_DEVSOURCE_ATTRIBUTE_SOURCE_TYPE_VIDCAP_GUID);
  if (FAILED(hr)) {
    result = SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to set MF device type: 0x%08x", hr);
    goto cleanup;
  }
 
  // Enumerate video capture devices
  hr = MFEnumDeviceSources(attr, &mf_devices, &mf_count);
  if (FAILED(hr)) {
    result = SET_ERRNO_SYS(ERROR_WEBCAM, "Failed to enumerate MF devices: 0x%08x", hr);
    goto cleanup;
  }
 
  if (mf_count == 0) {
    // No devices found - not an error, just return empty list
    goto cleanup;
  }
 
  // Allocate output array
  webcam_device_info_t *devices = SAFE_CALLOC(mf_count, sizeof(webcam_device_info_t), webcam_device_info_t *);
  if (!devices) {
    result = SET_ERRNO(ERROR_MEMORY, "Failed to allocate device info array");
    goto cleanup;
  }
 
  // Populate device info
  for (UINT32 i = 0; i < mf_count; i++) {
    devices[i].index = i;
 
    LPWSTR friendlyName = NULL;
    UINT32 nameLength = 0;
 
    hr = IMFActivate_GetAllocatedString(mf_devices[i], &MF_DEVSOURCE_ATTRIBUTE_FRIENDLY_NAME, &friendlyName,
                                        &nameLength);
    if (SUCCEEDED(hr) && friendlyName) {
      // Convert wide string to UTF-8
      int len = WideCharToMultiByte(CP_UTF8, 0, friendlyName, -1, NULL, 0, NULL, NULL);
      if (len > 0 && len < WEBCAM_DEVICE_NAME_MAX) {
        WideCharToMultiByte(CP_UTF8, 0, friendlyName, -1, devices[i].name, WEBCAM_DEVICE_NAME_MAX, NULL, NULL);
      } else {
        SAFE_STRNCPY(devices[i].name, "<Unknown>", WEBCAM_DEVICE_NAME_MAX);
      }
      CoTaskMemFree(friendlyName);
    } else {
      SAFE_STRNCPY(devices[i].name, "<Unknown>", WEBCAM_DEVICE_NAME_MAX);
    }
  }
 
  *out_devices = devices;
  *out_count = mf_count;
 
cleanup:
  if (mf_devices) {
    for (UINT32 i = 0; i < mf_count; i++) {
      if (mf_devices[i]) {
        IMFActivate_Release(mf_devices[i]);
      }
    }
    CoTaskMemFree((void *)mf_devices);
  }
  if (attr) {
    IMFAttributes_Release(attr);
  }
  if (mf_initialized) {
    MFShutdown();
  }
  if (com_initialized) {
    CoUninitialize();
  }
 
  return result;
}
 
void webcam_free_device_list(webcam_device_info_t *devices) {
  SAFE_FREE(devices);
}
 
#endif