File size: 21,494 Bytes
fed6c68
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
# Copyright 2025 Bytedance Ltd. and/or its affiliates
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from functools import partial
from typing import TYPE_CHECKING, Any, Callable, Dict, List, Sequence, Union

import torch

from veomni.utils.constants import AUDIO_INPUT_INDEX, IGNORE_INDEX, IMAGE_INPUT_INDEX, VIDEO_INPUT_INDEX
from veomni.utils.registry import Registry


if TYPE_CHECKING:
    from transformers import PreTrainedTokenizer, ProcessorMixin

    from .chat_template import ChatTemplate


DATA_TRANSFORM_REGISTRY = Registry("DataTransform")


def build_data_transform(transform_name: str, **kwargs) -> Callable:
    return partial(DATA_TRANSFORM_REGISTRY[transform_name], **kwargs)


def split_into_chunks(sequence: Sequence[int], chunk_size: int) -> List[List[int]]:
    """
    Splits a long sequence into chunks.
    """
    total_len = len(sequence)
    chunks = []
    for i in range(0, total_len, chunk_size):
        chunks.append(sequence[i : i + chunk_size])

    return chunks


@DATA_TRANSFORM_REGISTRY.register("plaintext")
def process_plaintext_example(
    example: Dict[str, Any],
    tokenizer: "PreTrainedTokenizer",
    max_seq_len: int,
    text_keys: Union[str, List[str]] = "content_split",
    **kwargs,
) -> List[Dict[str, "torch.Tensor"]]:
    examples = []
    if isinstance(text_keys, str):
        text_example = example[text_keys]
    elif isinstance(text_keys, list):
        for key in text_keys:
            if key in example:
                text_example = example[key]
                break
        else:
            raise ValueError(f"None of the keys {text_keys} are found in the example.")
    else:
        raise ValueError(f"text_keys must be a string or a list of strings, but got {type(text_keys)}")

    tokens = tokenizer.encode(text_example, add_special_tokens=False) + [tokenizer.eos_token_id]
    for input_ids in split_into_chunks(tokens, max_seq_len):
        examples.append(
            {
                "input_ids": torch.tensor(input_ids),
                "attention_mask": torch.tensor([1] * len(input_ids)),
                "labels": torch.tensor(input_ids),
            }
        )

    return examples


@DATA_TRANSFORM_REGISTRY.register("conversation")
def process_conversation_example(
    example: Dict[str, Any],
    chat_template: "ChatTemplate",
    max_seq_len: int,
    text_keys: Union[str, List[str]] = "messages",
    **kwargs,
) -> List[Dict[str, "torch.Tensor"]]:
    if isinstance(text_keys, str):
        text_example = example[text_keys]
    elif isinstance(text_keys, list):
        for key in text_keys:
            if key in example:
                text_example = example[key]
                break
        else:
            raise ValueError(f"None of the keys {text_keys} are found in the example.")
    else:
        raise ValueError(f"text_keys must be a string or a list of strings, but got {type(text_keys)}")

    tokenized_example = chat_template.encode_messages(text_example, max_seq_len=max_seq_len)
    tokenized_example = {k: torch.tensor(v) for k, v in tokenized_example.items()}
    return [tokenized_example]


@DATA_TRANSFORM_REGISTRY.register("dpo")
def process_dpo_example(
    example: Dict[str, Any],
    chat_template: "ChatTemplate" = None,
    tokenizer: "PreTrainedTokenizer" = None,
    max_seq_len: int = 2048,
    **kwargs,
) -> List[Dict[str, "torch.Tensor"]]:
    """Process a DPO preference pair into a single flat sample.

    Chosen and rejected sequences are concatenated into one 1-D tensor with
    ``position_ids`` that reset at the boundary so that flash-attention treats
    them as two independent sequences.  This format is directly compatible with
    ``MainCollator`` (packing + SP) — no DPO-specific collator is needed.

    Supported input formats:
      1. Conversation: {"chosen": [messages...], "rejected": [messages...]}
      2. Plaintext with prompt: {"prompt": str, "chosen": str, "rejected": str}

    Returns:
        A list with one dict.  Each value is a 1-D tensor of length
        ``len_chosen + len_rejected``.  Keys: ``input_ids``, ``attention_mask``,
        ``labels``, ``position_ids``.
    """
    chosen_raw = example["chosen"]
    rejected_raw = example["rejected"]

    if isinstance(chosen_raw, list):
        assert chat_template is not None, "chat_template is required for conversation-format DPO data"
        chosen_tok = chat_template.encode_messages(chosen_raw, max_seq_len=max_seq_len)
        rejected_tok = chat_template.encode_messages(rejected_raw, max_seq_len=max_seq_len)
    else:
        assert tokenizer is not None, "tokenizer is required for plaintext-format DPO data"
        prompt = example.get("prompt", "")
        chosen_text = prompt + chosen_raw
        rejected_text = prompt + rejected_raw

        chosen_ids = tokenizer.encode(chosen_text, add_special_tokens=True)[:max_seq_len]
        rejected_ids = tokenizer.encode(rejected_text, add_special_tokens=True)[:max_seq_len]
        prompt_ids = tokenizer.encode(prompt, add_special_tokens=True) if prompt else []
        prompt_len = len(prompt_ids)

        chosen_tok = {
            "input_ids": chosen_ids,
            "attention_mask": [1] * len(chosen_ids),
            "labels": [IGNORE_INDEX] * prompt_len + chosen_ids[prompt_len:],
        }
        rejected_tok = {
            "input_ids": rejected_ids,
            "attention_mask": [1] * len(rejected_ids),
            "labels": [IGNORE_INDEX] * prompt_len + rejected_ids[prompt_len:],
        }

    def _to_tensor(v):
        return v if isinstance(v, torch.Tensor) else torch.tensor(v)

    c_ids = _to_tensor(chosen_tok["input_ids"])
    r_ids = _to_tensor(rejected_tok["input_ids"])
    c_len = c_ids.shape[-1]
    r_len = r_ids.shape[-1]

    result = {
        "input_ids": torch.cat([c_ids, r_ids]),
        "attention_mask": torch.cat(
            [_to_tensor(chosen_tok["attention_mask"]), _to_tensor(rejected_tok["attention_mask"])]
        ),
        "labels": torch.cat([_to_tensor(chosen_tok["labels"]), _to_tensor(rejected_tok["labels"])]),
        "position_ids": torch.cat([torch.arange(c_len, dtype=torch.int64), torch.arange(r_len, dtype=torch.int64)]),
    }
    return [result]


@DATA_TRANSFORM_REGISTRY.register("classification")
def process_classification_example(
    example: dict[str, Any],
    tokenizer: "PreTrainedTokenizer",
    max_seq_len: int,
    text_keys: Union[str, list[str]] = "text",
    label_key: str = "label",
    **kwargs,
) -> list[dict[str, "torch.Tensor"]]:
    """
    Convert a single raw example into one classification training sample.

    Args:
        example:
            A single record from the dataset. Expected format (minimal):
                {
                    "<text_key>":  str,   # e.g. news article / sentence
                    "<label_key>": int,   # e.g. 0..(num_labels-1)
                    ...                   # other fields are ignored
                }
            By default:
                text_key  = "text"
                label_key = "label"

        tokenizer:
            A HuggingFace tokenizer used to tokenize the input text.

        max_seq_len:
            Maximum sequence length (in tokens). Text longer than this
            will be truncated to the first `max_seq_len` tokens.

        text_keys:
            Keys in `example` that contains the raw input text. If a list, the first key found in `example` will be used.

        label_key:
            Key in `example` that contains the class id. The value should be int-like.

    Returns:
        A list with exactly one sample dict:
            {
                "input_ids":      LongTensor[L],
                "attention_mask": LongTensor[L],
                "labels":         LongTensor[L],
                "position_ids":   LongTensor[L]
            }
    """
    # 1) text
    if isinstance(text_keys, str):
        text = example[text_keys]
    elif isinstance(text_keys, list):
        for key in text_keys:
            if key in example:
                text = example[key]
                break
        else:
            raise ValueError(f"None of the keys {text_keys} are found in the example.")
    else:
        raise ValueError(f"text_keys must be a string or a list of strings, but got {type(text_keys)}")

    # 2) label
    if label_key not in example:
        raise ValueError(f"Missing label key '{label_key}' in example.")
    try:
        label_val = int(example[label_key])
    except Exception as e:
        raise ValueError(f"Label '{example[label_key]}' is not an int-like value.") from e

    # 3) tokenize
    tokens: list[int] = tokenizer.encode(text, add_special_tokens=True)

    # 4) build samples
    examples: list[dict[str, torch.Tensor]] = []

    def build_sample(seq: list[int]) -> dict[str, "torch.Tensor"]:
        L = len(seq)
        token_labels = torch.full((L,), IGNORE_INDEX, dtype=torch.long)
        token_labels[L - 1] = label_val

        sample: dict[str, torch.Tensor] = {
            "input_ids": torch.tensor(seq, dtype=torch.long),
            "attention_mask": torch.ones(len(seq), dtype=torch.long),
            "labels": token_labels,
        }
        sample["position_ids"] = torch.arange(len(seq), dtype=torch.long)
        return sample

    if len(tokens) > max_seq_len:
        tokens = tokens[:max_seq_len]

    examples.append(build_sample(tokens))
    return examples


def _process_sample_qwen_vl_base(
    sample: Dict[str, Any],
    processor: "ProcessorMixin",
    chat_template: "ChatTemplate",
    position_id_func: "Callable",
    **kwargs,
):
    from .multimodal import conv_preprocess
    from .multimodal.image_utils import fetch_images
    from .multimodal.video_utils import fetch_videos_metadata

    source = kwargs.get("source_name") or sample.get("source") or sample.get("source_name")

    if "conversations" in sample and sample["conversations"] is not None and len(sample["conversations"]) > 0:
        conversations = sample["conversations"]
    else:
        conversations = sample
    conversations = conv_preprocess(source, conversations, **kwargs)

    token_num_inputs, image_inputs, video_inputs = {}, {}, {}
    image_grid_thw, video_grid_thw = None, None
    video_metadata = None

    if "images" in sample and sample["images"]:
        images = fetch_images(sample["images"], **kwargs)
        image_inputs = processor.image_processor(images=images, return_tensors="pt")
        image_grid_thw = image_inputs["image_grid_thw"]
        merge_length = processor.image_processor.merge_size**2
        image_token_num = image_grid_thw.prod(dim=-1) // merge_length
        token_num_inputs["image"] = image_token_num

    if "videos" in sample and sample["videos"]:
        videos, metadata, _, _ = fetch_videos_metadata(sample["videos"], **kwargs)
        video_inputs = processor.video_processor(
            videos=videos, video_metadata=metadata, return_tensors="pt", return_metadata=True
        )
        video_grid_thw = video_inputs["video_grid_thw"]
        video_metadata = video_inputs.pop("video_metadata", None)

        merge_length = processor.video_processor.merge_size**2
        video_token_num = video_grid_thw.prod(dim=-1) // merge_length
        token_num_inputs["video"] = video_token_num

    # Encoding
    encode_kwargs = {}
    if video_metadata is not None:
        encode_kwargs["video_metadata"] = video_metadata

    tokenized_example = chat_template.encode_messages(conversations, token_num_inputs, **encode_kwargs)

    tokenized_example = {
        k: (v if isinstance(v, torch.Tensor) else torch.tensor(v)) for k, v in tokenized_example.items()
    }

    input_ids = tokenized_example["input_ids"]
    attention_mask = tokenized_example["attention_mask"]

    # Masks and Token Types
    tokenized_example["image_mask"] = input_ids == IMAGE_INPUT_INDEX
    tokenized_example["video_mask"] = input_ids == VIDEO_INPUT_INDEX

    # Position IDs
    position_id_func_kwargs = {
        "input_ids": input_ids.unsqueeze(0),
        "image_grid_thw": image_grid_thw,
        "video_grid_thw": video_grid_thw,
        "attention_mask": attention_mask.unsqueeze(0),
    }

    mm_token_type_ids = torch.zeros_like(input_ids)
    mm_token_type_ids[tokenized_example["image_mask"]] = 1
    mm_token_type_ids[tokenized_example["video_mask"]] = 2
    tokenized_example["mm_token_type_ids"] = mm_token_type_ids
    position_id_func_kwargs["mm_token_type_ids"] = mm_token_type_ids.unsqueeze(0)

    position_id_returns = position_id_func(**position_id_func_kwargs)
    # Squeeze position_ids to match the per-sample (no batch dim) convention
    # used everywhere else in this dict.
    position_id_returns["position_ids"] = position_id_returns["position_ids"].squeeze().clone()
    # Only position_ids is propagated into the training feature dict. The
    # rope_deltas position_id_func also returns is generation-only (KV-cache
    # decode); the training forward always receives a precomputed
    # position_ids and never derives or reads rope_deltas.
    tokenized_example["position_ids"] = position_id_returns["position_ids"]

    # Final cleanup
    tokenized_example["input_ids"][tokenized_example["image_mask"]] = 0
    tokenized_example["input_ids"][tokenized_example["video_mask"]] = 0
    tokenized_example.update(image_inputs)
    tokenized_example.update(video_inputs)
    # image_inputs / video_inputs carry the HF processor's CPU `image_grid_thw`
    # / `video_grid_thw` tensors; the collator packs them (DataCollateInfo
    # pack_dim=0) and the model's metadata_collate_func hook derives the ViT
    # metadata from them. No per-sample `.tolist()` sidecar needed here.

    return [tokenized_example]


@DATA_TRANSFORM_REGISTRY.register("qwen2_vl")
@DATA_TRANSFORM_REGISTRY.register("qwen2_5_vl")
@DATA_TRANSFORM_REGISTRY.register("qwen3_vl")
@DATA_TRANSFORM_REGISTRY.register("qwen3_vl_moe")
@DATA_TRANSFORM_REGISTRY.register("qwen3_5")
@DATA_TRANSFORM_REGISTRY.register("qwen3_5_moe")
def process_sample_qwen_vl(
    sample: Dict[str, Any],
    processor: "ProcessorMixin",
    chat_template: "ChatTemplate",
    position_id_func: "Callable",
    **kwargs,
):
    """
    Unified processing function for Qwen-VL series models.
    Automatically determines whether to use mm_token_type_ids based on transformers version.
    """
    return _process_sample_qwen_vl_base(
        sample,
        processor,
        chat_template,
        position_id_func,
        **kwargs,
    )


@DATA_TRANSFORM_REGISTRY.register("qwen2_5_omni")
@DATA_TRANSFORM_REGISTRY.register("qwen3_omni_moe")
def process_sample_qwen_omni(
    sample: Dict[str, Any],
    processor: "ProcessorMixin",
    position_id_func: "Callable",
    **kwargs,
):
    from .multimodal import conv_preprocess
    from .multimodal.audio_utils import fetch_audios
    from .multimodal.image_utils import fetch_images
    from .multimodal.video_utils import fetch_videos

    QWEN_OMNI_SYSTEM_MESSAGE = (
        "You are Qwen, a virtual human developed by the Qwen Team, Alibaba Group, "
        "capable of perceiving auditory and visual inputs, as well as generating text and speech."
    )

    def get_omni_token_ids(processor: "ProcessorMixin") -> tuple[int, int, int]:
        tokenizer = getattr(processor, "tokenizer", processor)
        vocab = tokenizer.get_vocab()
        image_token_id = vocab.get("<|image_pad|>", vocab.get("<|IMAGE|>"))
        video_token_id = vocab.get("<|video_pad|>", vocab.get("<|VIDEO|>"))
        audio_token_id = vocab.get("<|audio_pad|>", vocab.get("<|AUDIO|>"))
        if image_token_id is None:
            raise ValueError("Cannot find image token (<|image_pad|> or <|IMAGE|>) in tokenizer vocab.")
        if video_token_id is None:
            raise ValueError("Cannot find video token (<|video_pad|> or <|VIDEO|>) in tokenizer vocab.")
        if audio_token_id is None:
            raise ValueError("Cannot find audio token (<|audio_pad|> or <|AUDIO|>) in tokenizer vocab.")
        return image_token_id, video_token_id, audio_token_id

    image_token_id, video_token_id, audio_token_id = get_omni_token_ids(processor)

    source = kwargs.get("source_name") or sample.get("source") or sample.get("source_name")
    conversations = (
        sample["conversations"] if ("conversations" in sample and len(sample["conversations"]) > 0) else sample
    )
    conversations = conv_preprocess(source, conversations, **kwargs)
    input_conversations = [
        {
            "role": "system",
            "content": [
                {
                    "type": "text",
                    "text": QWEN_OMNI_SYSTEM_MESSAGE,
                },
            ],
        },
    ]
    for conversation in conversations:
        contents = []
        for message in conversation[1:]:
            contents.append({"type": message[0], message[0]: message[1]})
        tmp_conv = {
            "role": conversation[0],
            "content": contents,
        }
        input_conversations.append(tmp_conv)
    text = processor.apply_chat_template(input_conversations, tokenize=False)

    images = sample.get("images", [])
    if images:
        images = fetch_images(images, **kwargs)
    else:
        images = []

    videos = sample.get("videos", [])
    if videos:
        videos, video_audios = fetch_videos(videos, **kwargs)
    else:
        videos, video_audios = [], []

    audios = sample.get("audios", [])
    if audios:
        audio_audios = fetch_audios(audios, **kwargs)
    else:
        audio_audios = []

    video_audios_iter = iter(video_audios)
    audio_audios_iter = iter(audio_audios)
    audios = []
    for item in input_conversations:
        for content in item["content"]:
            if content["type"] == "video":
                audios.append(next(video_audios_iter))
            elif content["type"] == "audio":
                audios.append(next(audio_audios_iter))

    model_inputs = processor(
        text=text,
        audios=audios,
        images=images,
        videos=videos,
        return_tensors="pt",
        padding=True,
    )
    model_inputs = model_inputs.data
    input_features = model_inputs.pop("input_features", None)
    feature_attention_mask = model_inputs.pop("feature_attention_mask", None)

    if feature_attention_mask is not None:
        audio_feature_lengths = torch.sum(feature_attention_mask, dim=1)
        valid_mask = audio_feature_lengths != 0
        input_features = input_features[valid_mask].permute(0, 2, 1)[feature_attention_mask[valid_mask].bool()]

        model_inputs["input_features"] = input_features
        model_inputs["audio_feature_lengths"] = audio_feature_lengths
    else:
        audio_feature_lengths = None

    input_ids = model_inputs["input_ids"].squeeze(0)
    image_mask = input_ids == image_token_id
    video_mask = input_ids == video_token_id
    audio_mask = input_ids == audio_token_id
    input_ids[image_mask] = IMAGE_INPUT_INDEX
    input_ids[video_mask] = VIDEO_INPUT_INDEX
    input_ids[audio_mask] = AUDIO_INPUT_INDEX

    position_id_returns = position_id_func(
        input_ids=input_ids.unsqueeze(0),
        image_grid_thw=model_inputs.get("image_grid_thw", None),
        video_grid_thw=model_inputs.get("video_grid_thw", None),
        attention_mask=model_inputs["attention_mask"],
        audio_seqlens=audio_feature_lengths,
        second_per_grids=model_inputs.pop("video_second_per_grid", None),
    )
    position_id_returns["position_ids"] = position_id_returns["position_ids"].clone()
    # Only position_ids is propagated — rope_deltas is generation-only; see
    # _process_sample_qwen_vl_base for the rationale. grid_thw tensors flow
    # through model_inputs and are packed by the collator.
    model_inputs["position_ids"] = position_id_returns["position_ids"]

    model_inputs["image_mask"] = image_mask
    model_inputs["video_mask"] = video_mask
    model_inputs["audio_mask"] = audio_mask
    input_ids[image_mask | video_mask | audio_mask] = 0
    model_inputs["input_ids"] = input_ids
    model_inputs["attention_mask"] = model_inputs["attention_mask"].squeeze(0)

    labels = torch.full_like(input_ids, fill_value=IGNORE_INDEX)
    tokenizer = getattr(processor, "tokenizer", processor)
    vocab = tokenizer.get_vocab()
    user_token_id = vocab.get("user")
    assistant_token_id = vocab.get("assistant")
    if user_token_id is None or assistant_token_id is None:
        raise ValueError("Cannot find user/assistant tokens in tokenizer vocab.")
    user_start_index = torch.where(input_ids == user_token_id)[0].tolist()
    assistant_start_index = torch.where(input_ids == assistant_token_id)[0].tolist()
    user_start_index.append(len(input_ids) + 1)
    user_i = 0
    for assis_i in assistant_start_index:
        while user_start_index[user_i] < assis_i:
            user_i += 1
        labels[assis_i + 2 : user_start_index[user_i] - 1] = input_ids[assis_i + 2 : user_start_index[user_i] - 1]
    model_inputs["labels"] = labels
    return [model_inputs]