tensormeta: Add APIs to create and access GstTensorMeta contents

Also document those APIs better.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/6000>

subprojects/gst-plugins-bad/gst-libs/gst/analytics/gsttensor.h

@@ -174,8 +174,6 @@ GstTensorDim * gst_tensor_get_dims (GstTensor * tensor, gsize * num_dims);
 GST_ANALYTICS_META_API
 GType gst_tensor_get_type (void);
 
-#define GST_TENSOR_MISSING_ID -1
-
 G_END_DECLS
 
 #endif /* __GST_TENSOR_H__ */

subprojects/gst-plugins-bad/gst-libs/gst/analytics/gsttensormeta.c

@@ -44,6 +44,11 @@ gst_tensor_meta_free (GstMeta * meta, GstBuffer * buffer)
   g_free (tmeta->tensors);
 }
 
+/**
+ * gst_tensor_meta_api_get_type: (skip)
+ *
+ * Since: 1.26
+ */
 GType
 gst_tensor_meta_api_get_type (void)
 {
@@ -123,6 +128,64 @@ gst_buffer_get_tensor_meta (GstBuffer * buffer)
       GST_TENSOR_META_API_TYPE);
 }
 
+/**
+ * gst_tensor_meta_set:
+ * @tmeta: a #GstTensorMeta
+ * @num_tensors: The number of tensors in the @tensors array
+ * @tensors: (in) (array length=num_tensors) (transfer full): An array of poiners to #GstTensor
+ *
+ * Sets tensors into the #GstTensorMeta
+ *
+ * Since: 1.26
+ */
+void
+gst_tensor_meta_set (GstTensorMeta * tmeta, guint num_tensors,
+    GstTensor ** tensors)
+{
+  guint i;
+
+  for (i = 0; i < tmeta->num_tensors; i++) {
+    gst_tensor_free (tmeta->tensors[i]);
+  }
+  g_free (tmeta->tensors);
+
+  tmeta->num_tensors = num_tensors;
+  tmeta->tensors = tensors;
+}
+
+/**
+ * gst_tensor_meta_get:
+ * @tmeta: A #GstTensorMeta
+ * @index: The number of the tensor to get
+ *
+ * Retrieves a tensor from the #GstTensorMeta, the index must be
+ * smaller than #GstTensorMeta.num_tensors
+ *
+ * Return: (transfer none): a GstTensor
+ *
+ * Since: 1.26
+ */
+const GstTensor *
+gst_tensor_meta_get (GstTensorMeta * tmeta, gsize index)
+{
+  g_return_val_if_fail (tmeta->tensors, NULL);
+  g_return_val_if_fail (index < tmeta->num_tensors, NULL);
+
+  return tmeta->tensors[index];
+}
+
+/**
+ * gst_tensor_meta_get_index_from_id:
+ * @meta: a #GstTensorMeta
+ * @id: The tensor id to look for
+ *
+ * Finds the first tensor with the requsted ID in the meta
+ *
+ * Return: The index of the tensor inthe meta, or -1 if
+ *  its not found.
+ *
+ * Since: 1.26
+ */
 gint
 gst_tensor_meta_get_index_from_id (GstTensorMeta * meta, GQuark id)
 {
@@ -131,5 +194,5 @@ gst_tensor_meta_get_index_from_id (GstTensorMeta * meta, GQuark id)
       return i;
   }
 
-  return GST_TENSOR_MISSING_ID;
+  return -1;
 }

subprojects/gst-plugins-bad/gst-libs/gst/analytics/gsttensormeta.h

@@ -49,9 +49,23 @@ typedef struct _GstTensorMeta
 
 G_BEGIN_DECLS
 
+/**
+ * GST_TENSOR_META_API_TYPE:
+ *
+ * The Tensor Meta API type
+ *
+ * Since: 1.26
+ */
 #define GST_TENSOR_META_API_TYPE \
   (gst_tensor_meta_api_get_type())
 
+/**
+ * GST_TENSOR_META_INFO: (skip)
+ *
+ * The Tensor Meta API Info
+ *
+ * Since: 1.26
+ */
 #define GST_TENSOR_META_INFO \
   (gst_tensor_meta_get_info())
 
@@ -61,6 +75,13 @@ GType gst_tensor_meta_api_get_type (void);
 GST_ANALYTICS_META_API
 const GstMetaInfo *gst_tensor_meta_get_info (void);
 
+GST_ANALYTICS_META_API
+void gst_tensor_meta_set (GstTensorMeta *tmeta, guint num_tensors,
+    GstTensor **tensors);
+
+GST_ANALYTICS_META_API
+const GstTensor *gst_tensor_meta_get (GstTensorMeta *tmeta, gsize index);
+
 GST_ANALYTICS_META_API
 gint gst_tensor_meta_get_index_from_id(GstTensorMeta *meta, GQuark id);
 

subprojects/gst-plugins-bad/gst/tensordecoders/gstssdobjectdetector.c

@@ -338,12 +338,10 @@ gst_ssd_object_detector_get_tensor_meta (GstSsdObjectDetector * object_detector,
     gint clasesIndex = gst_tensor_meta_get_index_from_id (tensor_meta,
         g_quark_from_static_string (GST_MODEL_OBJECT_DETECTOR_CLASSES));
 
-    if (boxesIndex == GST_TENSOR_MISSING_ID
-        || scoresIndex == GST_TENSOR_MISSING_ID
-        || numDetectionsIndex == GST_TENSOR_MISSING_ID)
+    if (boxesIndex == -1 || scoresIndex == -1 || numDetectionsIndex == -1)
       continue;
 
-    if (tensor_meta->num_tensors == 4 && clasesIndex == GST_TENSOR_MISSING_ID)
+    if (tensor_meta->num_tensors == 4 && clasesIndex == -1)
       continue;
 
     return tensor_meta;
@@ -435,9 +433,7 @@ DEFINE_GET_FUNC (guint32, UINT32_MAX)
   boxes_index = gst_tensor_meta_get_index_from_id (tmeta,
       g_quark_from_static_string (GST_MODEL_OBJECT_DETECTOR_BOXES));
 
-  if (numdetect_index == GST_TENSOR_MISSING_ID
-      || scores_index == GST_TENSOR_MISSING_ID
-      || numdetect_index == GST_TENSOR_MISSING_ID) {
+  if (numdetect_index == -1 || scores_index == -1 || numdetect_index == -1) {
     GST_WARNING ("Missing tensor data expected for SSD model");
     return;
   }
@@ -463,7 +459,7 @@ DEFINE_GET_FUNC (guint32, UINT32_MAX)
     goto cleanup;
   }
 
-  if (classes_index != GST_TENSOR_MISSING_ID &&
+  if (classes_index != -1 &&
       !gst_buffer_map (tmeta->tensors[classes_index]->data, &classes_map,
           GST_MAP_READ)) {
     GST_DEBUG_OBJECT (self, "Failed to map tensor memory for index %d",