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Robotics & Edge Computing Jetson & Embedded Systems Jetson TX2
1

hi：
Thank you for your help. I can already get the live stream camera via rtsp.
Now, I want to know how to get the decoded frame data in order to do my license plate recognition and subsequent car lamp detection algorithms.
There is still a problem, the vehicle tracking in deepstream-app, I can by what method, get a video of the time from the time the vehicle enters the scene to the scene, to save it to the local.
I look forward to your reply.

2

Hi,
Here is a similar query and there is no existing implementation in DS4.0.
You may check if you can follow NvCJR’s suggestion to implement it.

3

hi DaneLLL :
I want to use the osd_sink_pad_buffer_probe function in deepstream-test1 to save the decoded image. My code is as follows. Now, I don’t know which is the decoded frame structure. The saved image is incorrect. Can you give me some suggestions? Thank you very much.

static GstPadProbeReturn
osd_sink_pad_buffer_probe (GstPad * pad, GstPadProbeInfo * info,
    gpointer u_data)
{
    GstBuffer *buf = (GstBuffer *) info->data;
    guint num_rects = 0; 
    NvDsObjectMeta *obj_meta = NULL;
    guint vehicle_count = 0;
    guint person_count = 0;
    NvDsMetaList * l_frame = NULL;
    NvDsMetaList * l_obj = NULL;
    NvDsDisplayMeta *display_meta = 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);
        int offset = 0;
        for (l_obj = frame_meta->obj_meta_list; l_obj != NULL;
                l_obj = l_obj->next) {
            obj_meta = (NvDsObjectMeta *) (l_obj->data);
#if 1
char filename[200];
char* sFileDirPath="/usr/local/sys.txt";
sprintf(filename,"%s/%d.jpg",sFileDirPath,frame_number);
int ret;
int tick = 0;
int fd = -1;
fd = open(filename, O_CREAT|O_TRUNC|O_RDWR, 0666);
if (fd < 0)
{
    printf("share::writeFile open file %s, error %s\n", filename, strerror(errno));

    
    return -1;
}
ret = BlockWrite(fd, frame_meta, sizeof(frame_meta));
if (ret < 0)
{
    printf("share::writeFile open file error %s\n", strerror(errno));
    close(fd);
    if (errno == ENOSPC){
       // goto NO_SPACE_EXIT;
    }

    return -1;
}
close(fd);
#endif
            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++;
            }
        }
        display_meta = nvds_acquire_display_meta_from_pool(batch_meta);
        NvOSD_TextParams *txt_params  = &display_meta->text_params[0];
        display_meta->num_labels = 1;
        txt_params->display_text = g_malloc0 (MAX_DISPLAY_LEN);
        offset = snprintf(txt_params->display_text, MAX_DISPLAY_LEN, "Person = %d ", person_count);
        offset = snprintf(txt_params->display_text + offset , MAX_DISPLAY_LEN, "Vehicle = %d ", vehicle_count);

        /* Now set the offsets where the string should appear */
        txt_params->x_offset = 10;
        txt_params->y_offset = 12;

        /* Font , font-color and font-size */
        txt_params->font_params.font_name = "Serif";
        txt_params->font_params.font_size = 10;
        txt_params->font_params.font_color.red = 1.0;
        txt_params->font_params.font_color.green = 1.0;
        txt_params->font_params.font_color.blue = 1.0;
        txt_params->font_params.font_color.alpha = 1.0;

        /* Text background color */
        txt_params->set_bg_clr = 1;
        txt_params->text_bg_clr.red = 0.0;
        txt_params->text_bg_clr.green = 0.0;
        txt_params->text_bg_clr.blue = 0.0;
        txt_params->text_bg_clr.alpha = 1.0;

        nvds_add_display_meta_to_frame(frame_meta, display_meta);
    }

    g_print ("Frame Number = %d Number of objects = %d "
            "Vehicle Count = %d Person Count = %d\n",
            frame_number, num_rects, vehicle_count, person_count);
    frame_number++;
    return GST_PAD_PROBE_OK;
}
int BlockWrite(int fd, char *src, int size)
{
    int k = 0, l_wriSize = 0;
    int l_connFd = fd;
    int l_size = size;

    while(1)
    {
        k = write(l_connFd, src + l_wriSize, l_size - l_wriSize);
        if (k <= 0)
        {
            printf("blockWrite:: failed fd %d, %s\n", fd, strerror(errno));
            return -1;
        }

        l_wriSize += k;
        if (l_wriSize == l_size)
        {
            return 0;
        }
    }
}
4

Hi,
Please refer to 2, 5 in faq