# When using deepstream\_lpr\_app for license plate recognition, how to take a screenshot of the vehicle with the detection frame? **URL:** \ **Category:** DeepStream SDK\ **Created:** [December 8, 2021, 2:19am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421 "2021-12-08T02:19:04Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![user85575](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@user85575](https://forums.developer.nvidia.com/u/user85575)\ **Post date:** [December 8, 2021, 2:19am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/1 "2021-12-08T02:19:04Z")
Please provide complete information as applicable to your setup. \*\*• Hardware Platform (Jetson NX） \*\*• DeepStream Version 5.1 **• JetPack Version (valid for Jetson only)** **• TensorRT Version** **• NVIDIA GPU Driver Version (valid for GPU only)** \*\*• Issue Type( new requirements) \*\*• When using deepstream\_lpr\_app for license plate recognition, how to take a screenshot of the vehicle with the detection frame? We can use deepstream and opencv to take a screenshot of the target vehicle, but the resolution is low. ---
**Author:** ![kesong](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/kesong/32/101255_2.png) [@kesong](https://forums.developer.nvidia.com/u/kesong)\ **Post date:** [December 8, 2021, 11:50am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/3 "2021-12-08T11:50:23Z")
Seems the object is small. so the resolution is low. ---
**Author:** ![user85575](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@user85575](https://forums.developer.nvidia.com/u/user85575)\ **Post date:** [December 9, 2021, 2:25am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/4 "2021-12-09T02:25:26Z")
Yes, the smaller the target, the smaller the resolution.Thanks very much for helping. Actually what I want to ask is how to take a screenshot of the target with bounding box. ---
**Author:** ![kesong](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/kesong/32/101255_2.png) [@kesong](https://forums.developer.nvidia.com/u/kesong)\ **Post date:** [December 9, 2021, 11:31am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/5 "2021-12-09T11:31:32Z")
BBox will be draw onto video after nvdsosd. [https://docs.nvidia.com/metropolis/deepstream/dev-guide/text/DS\_plugin\_gst-nvdsosd.html](https://docs.nvidia.com/metropolis/deepstream/dev-guide/text/DS_plugin_gst-nvdsosd.html) ---
**Author:** ![user85575](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@user85575](https://forums.developer.nvidia.com/u/user85575)\ **Post date:** [December 14, 2021, 3:34am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/6 "2021-12-14T03:34:03Z")
@kesong Hello, I read the description you posted about nvdsosd, and I also put the probe after calling nvdsosd. Then I refer to [How to save the complete frame with bounding boxes in deepstream-image-meta-test](https://forums.developer.nvidia.com/t/how-to-save-the-complete-frame-with-bounding-boxes-in-deepstream-image-meta-test/148042)? u=user85575 and [Deepstream save image with bounding box - #8 by Mike](https://forums.developer.nvidia.com/t/deepstream-save-image-with-bounding-box/123717/8) these two posts. And encapsulated a function with osd\_sink\_pad\_buffer\_probe in the deepstream\_image\_meta\_test example, but no screenshots appeared after running. Below is the program I wrote, please help me. ```auto int write_frame2(GstBuffer *buf, char *picture) { NvDsMetaList * l_frame = NULL; NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta (buf); NvDsObjectMeta *obj_meta = NULL; NvDsMetaList * l_obj = NULL; for (l_frame = batch_meta->frame_meta_list; l_frame != NULL; l_frame = l_frame->next) { NvDsFrameMeta *frame_meta = (NvDsFrameMeta *) (l_frame->data); if (!frame_meta) { continue; } for (l_obj = frame_meta->obj_meta_list; l_obj != NULL; l_obj = l_obj->next) { obj_meta = (NvDsObjectMeta *) (l_obj->data); if (!obj_meta) { continue; } /* For Demonstration Purposes we are writing metadata to jpeg images of * only vehicles for the first 100 frames only. * The files generated have a 'OSD' prefix. */ NvDsUserMetaList *usrMetaList = obj_meta->obj_user_meta_list; FILE *file; printf("1111111111111111111\n"); while (usrMetaList != NULL) { printf("000000000000000\n"); NvDsUserMeta *usrMetaData = (NvDsUserMeta *) usrMetaList->data; if (usrMetaData->base_meta.meta_type == NVDS_CROP_IMAGE_META) { NvDsObjEncOutParams *enc_jpeg_image = (NvDsObjEncOutParams *) usrMetaData->user_meta_data; /* Write to File */ file = fopen (picture, "wb"); fwrite (enc_jpeg_image->outBuffer, sizeof (uint8_t), enc_jpeg_image->outLen, file); fclose (file); usrMetaList = NULL; } else { usrMetaList = usrMetaList->next; } } } } return 0; } ``` Call function command: `write_frame2(buf, "tmp/test.jpg");` Through debugging, it is found that the variable usrMetaList is always NULL, so the picture cannot be saved.Please help me. ---
**Author:** ![kesong](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/kesong/32/101255_2.png) [@kesong](https://forums.developer.nvidia.com/u/kesong)\ **Post date:** [December 27, 2021, 9:04am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/7 "2021-12-27T09:04:00Z")
**There is no update from you for a period, assuming this is not an issue any more. Hence we are closing this topic. If need further support, please open a new one. Thanks** Can you check if you encoder the pic in nvds\_obj\_enc\_process() in the deepstream\_image\_meta\_test? ---
**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\ **Post date:** [January 25, 2022, 2:08am UTC](https://forums.developer.nvidia.com/t/when-using-deepstream-lpr-app-for-license-plate-recognition-how-to-take-a-screenshot-of-the-vehicle-with-the-detection-frame/197421/9 "2022-01-25T02:08:14Z")
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