dshow_cycle_devices(AVFormatContext *avctx, ICreateDevEnum *devenum, enum dshowDeviceType devtype, IBaseFilter **pfilter) { struct dshow_ctx *ctx = avctx->priv_data; IBaseFilter *device_filter = NULL; IEnumMoniker *classenum = NULL; IMoniker *m = NULL; const char *device_name = ctx->device_name[devtype]; int skip = (devtype == VideoDevice) ? ctx->video_device_number : ctx->audio_device_number; int r; const GUID *device_guid[2] = { &CLSID_VideoInputDeviceCategory, &CLSID_AudioInputDeviceCategory }; const char *devtypename = (devtype == VideoDevice) ? "video" : "audio"; r = ICreateDevEnum_CreateClassEnumerator(devenum, device_guid[devtype], (IEnumMoniker **) &classenum, 0); if (r != S_OK) { av_log(avctx, AV_LOG_ERROR, "Could not enumerate %s devices.\n", devtypename); return AVERROR(EIO); } while (!device_filter && IEnumMoniker_Next(classenum, 1, &m, NULL) == S_OK) { IPropertyBag *bag = NULL; char *buf = NULL; VARIANT var; r = IMoniker_BindToStorage(m, 0, 0, &IID_IPropertyBag, (void *) &bag); if (r != S_OK) goto fail1; var.vt = VT_BSTR; r = IPropertyBag_Read(bag, L"FriendlyName", &var, NULL); if (r != S_OK) goto fail1; buf = dup_wchar_to_utf8(var.bstrVal); if (pfilter) { if (strcmp(device_name, buf)) goto fail1; if (!skip--) IMoniker_BindToObject(m, 0, 0, &IID_IBaseFilter, (void *) &device_filter); } else { av_log(avctx, AV_LOG_INFO, " \"%s\"\n", buf); } fail1: if (buf) av_free(buf); if (bag) IPropertyBag_Release(bag); IMoniker_Release(m); } IEnumMoniker_Release(classenum); if (pfilter) { if (!device_filter) { av_log(avctx, AV_LOG_ERROR, "Could not find %s device.\n", devtypename); return AVERROR(EIO); } *pfilter = device_filter; } return 0; }