def build_data_multi_img_gt(self):
        """each text may have multiple ground_truth image, e.g., ssv2"""
        img_id = 0
        for txt_id, ann in enumerate(self.raw_anno_list):
            self.text.append(pre_text(ann["caption"]))
            self.txt2img[txt_id] = []
            _images = ann["image"] \
                if isinstance(ann["image"], list) else [ann["image"], ]
            for i, image in enumerate(_images):
                self.image.append(image)
                self.txt2img[txt_id].append(img_id)
                self.img2txt[img_id] = txt_id
                img_id += 1
each text may have multiple ground_truth image, e.g., ssv2
video_chat2/dataset/pt_dataset.py