libavfilter/dnn_bakcend_openvino: Add automatic input/output detection

Now when using openvino backend, user doesn't need to set input/output
names in command line. Model ports will be automatically detected.

For example:
ffmpeg -i input.png -vf \
dnn_detect=dnn_backend=openvino:model=model.xml:input=image:\
output=detection_out -y output.png

can be simplified to:
ffmpeg -i input.png -vf dnn_detect=dnn_backend=openvino:model=model.xml\
 -y output.png

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

1 files changed, 12 insertions, 9 deletions

diff --git a/libavfilter/dnn_filter_common.c b/libavfilter/dnn_filter_common.c
index 3b9182c1d1..f012d450a2 100644
--- a/libavfilter/dnn_filter_common.c
+++ b/libavfilter/dnn_filter_common.c
@@ -57,15 +57,17 @@ int ff_dnn_init(DnnContext *ctx, DNNFunctionType func_type, AVFilterContext *fil
         av_log(filter_ctx, AV_LOG_ERROR, "model file for network is not specified\n");
         return AVERROR(EINVAL);
     }
-    if (!ctx->model_inputname) {
-        av_log(filter_ctx, AV_LOG_ERROR, "input name of the model network is not specified\n");
-        return AVERROR(EINVAL);
-    }
 
-    ctx->model_outputnames = separate_output_names(ctx->model_outputnames_string, "&", &ctx->nb_outputs);
-    if (!ctx->model_outputnames) {
-        av_log(filter_ctx, AV_LOG_ERROR, "could not parse model output names\n");
-        return AVERROR(EINVAL);
+    if (ctx->backend_type == DNN_TF) {
+        if (!ctx->model_inputname) {
+            av_log(filter_ctx, AV_LOG_ERROR, "input name of the model network is not specified\n");
+            return AVERROR(EINVAL);
+        }
+        ctx->model_outputnames = separate_output_names(ctx->model_outputnames_string, "&", &ctx->nb_outputs);
+        if (!ctx->model_outputnames) {
+            av_log(filter_ctx, AV_LOG_ERROR, "could not parse model output names\n");
+            return AVERROR(EINVAL);
+        }
     }
 
     ctx->dnn_module = ff_get_dnn_module(ctx->backend_type, filter_ctx);
@@ -113,8 +115,9 @@ int ff_dnn_get_input(DnnContext *ctx, DNNData *input)
 
 int ff_dnn_get_output(DnnContext *ctx, int input_width, int input_height, int *output_width, int *output_height)
 {
+    char * output_name = ctx->model_outputnames ? ctx->model_outputnames[0] : NULL;
     return ctx->model->get_output(ctx->model->model, ctx->model_inputname, input_width, input_height,
-                                    (const char *)ctx->model_outputnames[0], output_width, output_height);
+                                    (const char *)output_name, output_width, output_height);
 }
 
 int ff_dnn_execute_model(DnnContext *ctx, AVFrame *in_frame, AVFrame *out_frame)