libavfilter/vf_dnn_detect: Add input pad

Add input pad to get model input resolution. Detection models always
have fixed input size. And the output coordinators are based on the
input resolution, so we need to get input size to map coordinators to
our real output frames.

Signed-off-by: Wenbin Chen <wenbin.chen@intel.com>
Reviewed-by: Guo Yejun <yejun.guo@intel.com>

libavfilter/dnn/dnn_backend_openvino.c

@@ -1073,9 +1073,15 @@ static int get_input_ov(void *model, DNNData *input, const char *input_name)
         return AVERROR(ENOSYS);
     }
 
-    input->channels = dims[1];
-    input->height   = input_resizable ? -1 : dims[2];
-    input->width    = input_resizable ? -1 : dims[3];
+    if (dims[1] <= 3) { // NCHW
+        input->channels = dims[1];
+        input->height   = input_resizable ? -1 : dims[2];
+        input->width    = input_resizable ? -1 : dims[3];
+    } else { // NHWC
+        input->height   = input_resizable ? -1 : dims[1];
+        input->width    = input_resizable ? -1 : dims[2];
+        input->channels = dims[3];
+    }
     input->dt       = precision_to_datatype(precision);
 
     return 0;
@@ -1105,9 +1111,15 @@ static int get_input_ov(void *model, DNNData *input, const char *input_name)
                 return DNN_GENERIC_ERROR;
             }
 
-            input->channels = dims.dims[1];
-            input->height   = input_resizable ? -1 : dims.dims[2];
-            input->width    = input_resizable ? -1 : dims.dims[3];
+            if (dims[1] <= 3) { // NCHW
+                input->channels = dims[1];
+                input->height   = input_resizable ? -1 : dims[2];
+                input->width    = input_resizable ? -1 : dims[3];
+            } else { // NHWC
+                input->height   = input_resizable ? -1 : dims[1];
+                input->width    = input_resizable ? -1 : dims[2];
+                input->channels = dims[3];
+            }
             input->dt       = precision_to_datatype(precision);
             return 0;
         }

libavfilter/vf_dnn_detect.c

@@ -705,13 +705,39 @@ static av_cold void dnn_detect_uninit(AVFilterContext *context)
     free_detect_labels(ctx);
 }
 
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *context     = inlink->dst;
+    DnnDetectContext *ctx = context->priv;
+    DNNData model_input;
+    int ret;
+
+    ret = ff_dnn_get_input(&ctx->dnnctx, &model_input);
+    if (ret != 0) {
+        av_log(ctx, AV_LOG_ERROR, "could not get input from the model\n");
+        return ret;
+    }
+    ctx->scale_width = model_input.width == -1 ? inlink->w : model_input.width;
+    ctx->scale_height = model_input.height ==  -1 ? inlink->h : model_input.height;
+
+    return 0;
+}
+
+static const AVFilterPad dnn_detect_inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_input,
+    },
+};
+
 const AVFilter ff_vf_dnn_detect = {
     .name          = "dnn_detect",
     .description   = NULL_IF_CONFIG_SMALL("Apply DNN detect filter to the input."),
     .priv_size     = sizeof(DnnDetectContext),
     .init          = dnn_detect_init,
     .uninit        = dnn_detect_uninit,
-    FILTER_INPUTS(ff_video_default_filterpad),
+    FILTER_INPUTS(dnn_detect_inputs),
     FILTER_OUTPUTS(ff_video_default_filterpad),
     FILTER_PIXFMTS_ARRAY(pix_fmts),
     .priv_class    = &dnn_detect_class,