Jetson Nano 系列之：保存整张图片

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Jetson Nano 系列之：保存整张图片

2024-07-15 02:17| 来源: 网络整理| 查看: 265

一、保存特征图片

在英伟达官方例子deepstream-image-meta-test代码中，提供了保存特征区域(ROI)的代码：

static GstPadProbeReturn pgie_src_pad_buffer_probe(GstPad *pad, GstPadProbeInfo *info, gpointer ctx) { GstBuffer *buf = (GstBuffer *)info->data; GstMapInfo inmap = GST_MAP_INFO_INIT; if (!gst_buffer_map(buf, &inmap, GST_MAP_READ)) { GST_ERROR("input buffer mapinfo failed"); return GST_FLOW_ERROR; } NvBufSurface *ip_surf = (NvBufSurface *)inmap.data; gst_buffer_unmap(buf, &inmap); NvDsObjectMeta *obj_meta = NULL; guint vehicle_count = 0; guint person_count = 0; NvDsMetaList *l_frame = NULL; NvDsMetaList *l_obj = NULL; NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta(buf); for (l_frame = batch_meta->frame_meta_list; l_frame != NULL; l_frame = l_frame->next) { NvDsFrameMeta *frame_meta = (NvDsFrameMeta *)(l_frame->data); guint num_rects = 0; 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->class_id == PGIE_CLASS_ID_VEHICLE) { vehicle_count++; num_rects++; } if (obj_meta->class_id == PGIE_CLASS_ID_PERSON) { person_count++; num_rects++; } /* Conditions that user needs to set to encode the detected objects of * interest. Here, by default all the detected objects are encoded. * For demonstration, we will encode the first object in the frame */ if ((obj_meta->class_id == PGIE_CLASS_ID_PERSON || obj_meta->class_id == PGIE_CLASS_ID_VEHICLE) && num_rects == 1) { NvDsObjEncUsrArgs userData = {0}; /* To be set by user */ userData.saveImg = save_img; userData.attachUsrMeta = attach_user_meta; /* Set if Image scaling Required */ userData.scaleImg = FALSE; userData.scaledWidth = 0; userData.scaledHeight = 0; /* Preset */ userData.objNum = num_rects; /* Quality */ userData.quality = 80; /*Main Function Call */ nvds_obj_enc_process(ctx, &userData, ip_surf, obj_meta, frame_meta); } } } nvds_obj_enc_finish(ctx); return GST_PAD_PROBE_OK; }

这段代码关键是调用了nvds_obj_enc_process生成图片，默认的图片名称为"frame-number_stream-number_object-number_object-type_widthxheight.jpg"，例如0_2_3_PERSON_126x148.jpg，保存在程序的同级目录下。

二、保存完整图片

根据英伟达开发者论坛的帖子，保存完整图片的代码：

static GstPadProbeReturn pgie_src_pad_buffer_probe (GstPad * pad, GstPadProbeInfo * info, gpointer ctx) { GstBuffer *buf = (GstBuffer *) info->data; GstMapInfo inmap = GST_MAP_INFO_INIT; if (!gst_buffer_map (buf, &inmap, GST_MAP_READ)) { GST_ERROR ("input buffer mapinfo failed"); return GST_FLOW_ERROR; } NvBufSurface *ip_surf = (NvBufSurface *) inmap.data; gst_buffer_unmap (buf, &inmap); NvDsObjectMeta *obj_meta = NULL; NvDsMetaList *l_frame = NULL; NvDsMetaList *l_obj = NULL; NvDsBatchMeta *batch_meta = gst_buffer_get_nvds_batch_meta (buf); for (l_frame = batch_meta->frame_meta_list; l_frame != NULL; l_frame = l_frame->next) { NvDsFrameMeta *frame_meta = (NvDsFrameMeta *) (l_frame->data); guint num_rects = 0; 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->class_id == 0) { num_rects++; } /* Conditions that user needs to set to encode the detected objects of * interest. Here, by default all the detected objects are encoded. * For demonstration, we will encode the first object in the frame */ if ( frame_meta->source_id == 0 && obj_meta->class_id == 0 && num_rects == 1 ) { NvDsObjEncUsrArgs userData = { 0 }; /* To be set by user */ userData.saveImg = TRUE; userData.attachUsrMeta = TRUE; /* Set if Image scaling Required */ userData.scaleImg = FALSE; userData.scaledWidth = 0; userData.scaledHeight = 0; /* Preset */ userData.objNum = num_rects; obj_meta->rect_params.width = frame_meta->source_frame_width ; obj_meta->rect_params.height = frame_meta->source_frame_height ; obj_meta->rect_params.top = 0.0f ; obj_meta->rect_params.left = 0.0f ; nvds_obj_enc_process (ctx, &userData, ip_surf, obj_meta, frame_meta); } } } nvds_obj_enc_finish (ctx); return GST_PAD_PROBE_OK; }

其中，关键部分是

obj_meta->rect_params.width = frame_meta->source_frame_width ; obj_meta->rect_params.height = frame_meta->source_frame_height ;

三、设置文件名

使用userData的fileNameImg来设置文件名，如下代码将文件名保存为images/1.jpg，images/2.jpg...。

char fileNameString[30]; snprintf(userData.fileNameImg, sizeof(userData.fileNameImg), "images/%d.jpg", ++image_index); 四、未检测到特征的图片保存

如果我们想把未检测到特征(例如人）的图片存一下，看看是不是误判，会遇到一个问题：obj_meta = (NvDsObjectMeta *) (l_obj->data); 这句执行不到，obj_meta 等于 NULL。没有查到NvDsObjectMeta如果创建新实例，我的做法是定义一个全局的NvDsObjectMeta *obj_meta = NULL，用前次不为NULL的obj_meta传递给nvds_obj_enc_process保存即可。

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Jetson Nano 系列之：保存整张图片

Jetson Nano 系列之：保存整张图片

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