From 12909f3b90b6919c64f2118c43aadfe41bb99f75 Mon Sep 17 00:00:00 2001
From: WesKwong <weskwong@outlook.com>
Date: Wed, 24 Sep 2025 17:21:05 +0800
Subject: [PATCH 1/2] fix: Resolve unexpected video frame dropping for
 multi-video inputs

This commit addresses a bug where the InternVL preprocessor would incorrectly drop one video frame from subsequent videos in a multi-video input.

This issue was reported in: https://github.com/OpenGVLab/InternVL/issues/1178
---
 .../models/internvl/processing_internvl.py     | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/src/transformers/models/internvl/processing_internvl.py b/src/transformers/models/internvl/processing_internvl.py
index 12e6a6163ba8..7c3434174763 100644
--- a/src/transformers/models/internvl/processing_internvl.py
+++ b/src/transformers/models/internvl/processing_internvl.py
@@ -98,7 +98,7 @@ def _insert_media_placeholders(
         video_num_patches: list[int],
         image_num_patches_indices: np.ndarray,
         video_num_patches_indices: np.ndarray,
-        video_patch_indices: np.ndarray,
+        video_frame_indices: np.ndarray,
     ):
         """
         Processes interleaved text with <image> and <video> placeholders, replacing them with appropriate
@@ -132,13 +132,13 @@ def _insert_media_placeholders(
                     # Get the slice of patches corresponding to the current video
                     # Here we need to account for both the multiple video frames and the potential multiple patches per frame
                     # As of now, InternVL only supports one patch per frame, but we keep the code flexible for future updates
-                    current_patch_index = video_patch_indices[video_index - 1] if video_index > 0 else 0
-                    end_patch_index = video_patch_indices[video_index]
-                    start_index = video_num_patches_indices[current_patch_index] if video_index > 0 else 0
-                    end_index = video_num_patches_indices[end_patch_index - 1]
+                    start_frame_index = video_frame_indices[video_index - 1] if video_index > 0 else 0
+                    end_frame_index = video_frame_indices[video_index]
+                    start_index = video_num_patches_indices[start_frame_index - 1] if start_frame_index > 0 else 0
+                    end_index = video_num_patches_indices[end_frame_index - 1]
                     image_video_patches.append(video_pixel_values[start_index:end_index])
                     # Get the number of patches per frame and replace the video placeholder with the correct number of image tokens
-                    num_patches = list(video_num_patches[current_patch_index:end_patch_index])
+                    num_patches = list(video_num_patches[start_frame_index:end_frame_index])
                     video_prompt = "\n".join(
                         f"Frame{i + 1}: {self.start_image_token}{self.image_token * self.image_seq_length * num_patches[i]}{self.end_image_token}"
                         for i in range(len(num_patches))
@@ -211,7 +211,7 @@ def __call__(
         image_pixel_values = None
         video_pixel_values = None
         image_num_patches_indices = np.array([0])
-        video_patch_indices = np.array([0])
+        video_frame_indices = np.array([0])
         video_num_patches_indices = np.array([0])
         if images is not None:
             images = self.image_processor.fetch_images(images)
@@ -227,7 +227,7 @@ def __call__(
             # Obtain per frame information first and then flatten to (BS * T, ...)
             num_frames_per_video = [len(video) for video in video_pixel_values]
             video_num_patches = [1 for frames in num_frames_per_video for _ in range(frames)]
-            video_patch_indices = np.cumsum(num_frames_per_video)
+            video_frame_indices = np.cumsum(num_frames_per_video)
             video_num_patches_indices = np.cumsum(video_num_patches)
             video_pixel_values = video_pixel_values.flatten(0, 1)
 
@@ -240,7 +240,7 @@ def __call__(
                 video_num_patches,
                 image_num_patches_indices,
                 video_num_patches_indices,
-                video_patch_indices,
+                video_frame_indices,
             )
             if images is not None and image_index != len(images):
                 raise ValueError("Number of image placeholders in the prompt does not match the number of images.")

From 4aad37ffca0e4d0568433849d9060aef47729617 Mon Sep 17 00:00:00 2001
From: WesKwong <weskwong@outlook.com>
Date: Wed, 24 Sep 2025 21:07:36 +0800
Subject: [PATCH 2/2] fix: update video output length calculation

---
 tests/models/internvl/test_processing_internvl.py | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/tests/models/internvl/test_processing_internvl.py b/tests/models/internvl/test_processing_internvl.py
index 6a510c89aafa..e924935207bf 100644
--- a/tests/models/internvl/test_processing_internvl.py
+++ b/tests/models/internvl/test_processing_internvl.py
@@ -345,24 +345,20 @@ def _test_apply_chat_template(
         for idx, url in enumerate(input_data[:batch_size]):
             batch_messages[idx][0]["content"] = [batch_messages[idx][0]["content"][0], {"type": modality, "url": url}]
 
+        num_frames_per_video = 2  # by default no more than 2 frames, otherwise too slow
         out_dict = processor.apply_chat_template(
             batch_messages,
             add_generation_prompt=True,
             tokenize=True,
             return_dict=True,
             return_tensors="pt",
-            num_frames=2,  # by default no more than 2 frames, otherwise too slow
+            num_frames=num_frames_per_video,
         )
         self.assertTrue(self.videos_input_name in out_dict)
         self.assertEqual(len(out_dict["input_ids"]), batch_size)
         self.assertEqual(len(out_dict["attention_mask"]), batch_size)
 
-        # InternVL internally collects frames from all the videos in a batch and flattens the batch dimension (B T C H W) -> (B*T C H W) then patches and removes the frames
-        # hence output length does not equal batch size
-        # removed hardcoded video length check video_len = 2 if batch_size == 1 else 3
-        # from experiment video_len looks like batch_size + 1
-        # TODO: update expected video_len calculation based on the internal processing logic of InternVLProcessor
-        output_len = batch_size + 1 if modality == "video" else batch_size
+        output_len = num_frames_per_video * batch_size if modality == "video" else batch_size
         self.assertEqual(len(out_dict[self.videos_input_name]), output_len)
         for k in out_dict:
             self.assertIsInstance(out_dict[k], torch.Tensor)