[FFmpeg-devel] [PATCH FFmpeg 1/15] libavutil: add detectionbbox util functions

* [FFmpeg-devel] [PATCH FFmpeg 1/15] libavutil: add detectionbbox util functions
@ 2025-03-08 14:58 m.kaindl0208
  2025-03-08 17:52 ` Sean McGovern
  0 siblings, 1 reply; 2+ messages in thread
From: m.kaindl0208 @ 2025-03-08 14:58 UTC (permalink / raw)
  To: ffmpeg-devel

Those functions will be used by classify in the upcoming patches.

Try the new filters using my Github Repo https://github.com/MaximilianKaindl/DeepFFMPEGVideoClassification.

Any Feedback is appreciated!

Signed-off-by: MaximilianKaindl <m.kaindl0208@gmail.com>
---
 libavutil/detection_bbox.c | 54 ++++++++++++++++++++++++++++++++++++++
 libavutil/detection_bbox.h | 31 ++++++++++++++++++++++
 2 files changed, 85 insertions(+)

diff --git a/libavutil/detection_bbox.c b/libavutil/detection_bbox.c index cb157b355b..378233121d 100644
--- a/libavutil/detection_bbox.c
+++ b/libavutil/detection_bbox.c
@@ -18,6 +18,7 @@
 
 #include "detection_bbox.h"
 #include "mem.h"
+#include "libavutil/avstring.h"
 
 AVDetectionBBoxHeader *av_detection_bbox_alloc(uint32_t nb_bboxes, size_t *out_size)  { @@ -71,3 +72,56 @@ AVDetectionBBoxHeader *av_detection_bbox_create_side_data(AVFrame *frame, uint32
 
     return header;
 }
+
+int av_detection_bbox_fill_with_best_labels(char **labels, float 
+*probabilities, int num_labels, AVDetectionBBox *bbox, int max_classes_per_box, float confidence_threshold) {
+    int i, j, minpos, ret;
+    float min;
+
+    if (!labels || !probabilities || !bbox) {
+        return AVERROR(EINVAL);
+    }
+
+    for (i = 0; i < num_labels; i++) {
+        if (probabilities[i] >= confidence_threshold) {
+            if (bbox->classify_count >= max_classes_per_box) {
+                // Find lowest probability classification
+                min = av_q2d(bbox->classify_confidences[0]);
+                minpos = 0;
+                for (j = 1; j < bbox->classify_count; j++) {
+                    float prob = av_q2d(bbox->classify_confidences[j]);
+                    if (prob < min) {
+                        min = prob;
+                        minpos = j;
+                    }
+                }
+
+                if (probabilities[i] > min) {
+                    ret = av_detection_bbox_set_content(bbox, labels[i], minpos, probabilities[i]);
+                    if (ret < 0)
+                        return ret;
+                }
+            } else {
+                ret = av_detection_bbox_set_content(bbox, labels[i], bbox->classify_count, probabilities[i]);
+                if (ret < 0)
+                    return ret;
+                bbox->classify_count++;
+            }
+        }
+    }
+    return 0;
+}
+
+int av_detection_bbox_set_content(AVDetectionBBox *bbox, char *label, 
+int index, float probability) {
+    // Set probability
+    bbox->classify_confidences[index] = av_make_q((int)(probability * 
+10000), 10000);
+
+    // Copy label with size checking
+    if (av_strlcpy(bbox->classify_labels[index], label, AV_DETECTION_BBOX_LABEL_NAME_MAX_SIZE) >=
+        AV_DETECTION_BBOX_LABEL_NAME_MAX_SIZE) {
+        av_log(NULL, AV_LOG_WARNING, "Label truncated in set_prob_and_label_of_bbox\n");
+    }
+
+    return 0;
+}
diff --git a/libavutil/detection_bbox.h b/libavutil/detection_bbox.h index 011988052c..27d749ad59 100644
--- a/libavutil/detection_bbox.h
+++ b/libavutil/detection_bbox.h
@@ -105,4 +105,35 @@ AVDetectionBBoxHeader *av_detection_bbox_alloc(uint32_t nb_bboxes, size_t *out_s
  * AV_FRAME_DATA_DETECTION_BBOXES and initializes the variables.
  */
 AVDetectionBBoxHeader *av_detection_bbox_create_side_data(AVFrame *frame, uint32_t nb_bboxes);
+
+/**
+ * Fills an AVDetectionBBox structure with the best labels based on probabilities.
+ *
+ * This function selects up to max_classes_per_box labels with the 
+highest probabilities
+ * that exceed the given confidence threshold, and assigns them to the bounding box.
+ *
+ * @param labels Array of label strings
+ * @param probabilities Array of probability values corresponding to 
+each label
+ * @param num_labels Number of elements in the labels and probabilities 
+arrays
+ * @param bbox Pointer to the AVDetectionBBox structure to be filled
+ * @param max_classes_per_box Maximum number of classes to assign to 
+the bounding box
+ * @param confidence_threshold Minimum probability value required for a 
+label to be considered
+ * @return 0 on success, negative error code on failure  */ int 
+av_detection_bbox_fill_with_best_labels(char **labels, float 
+*probabilities, int num_labels, AVDetectionBBox *bbox, int 
+max_classes_per_box, float confidence_threshold);
+
+/**
+ * Sets the content of an AVDetectionBBox at the specified index.
+ *
+ * This function assigns a label and its associated probability to the 
+specified index
+ * in the bounding box's internal storage.
+ *
+ * @param bbox Pointer to the AVDetectionBBox structure to modify
+ * @param label The class label to assign (will be copied internally)
+ * @param index The index at which to store the label and probability
+ * @param probability The confidence score/probability for this label
+ * @return 0 on success
+ */
+int av_detection_bbox_set_content(AVDetectionBBox *bbox, char *label, 
+int index, float probability);
+
 #endif
--
2.34.1


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