REVIEW 5 major objections 6 minor 38 references
Video Editing for Audio-Visual Dubbing
T0 review · 5 major / 6 minor · reviewed 2026-08-07 · deepseek-v4-flash
Pith's one-line read Dubbing as video editing, not generation, preserves occlusions and identity while lips follow new audio.
desk verdict EdiDub is a solid dubbing system with a genuinely new conditioning scheme, but the paper's central 'editing, not inpainting' claim is not actually measured. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
Three components carry the argument. The first is an optimized visual reference: during training, each frame is paired with a same-identity frame at least five frames away whose facial landmarks, excluding the lips, are closest; this teaches the model to copy spatial details while ignoring the reference mouth, and the same mechanism transfers to inference where the reference is the original frame. The second is DDIM inversion, which converts the original clip conditioned on its own speech into an initial noise latent, so the edit starts from a faithful reconstruction. The third is a quantized HuBERT speech representation with a single-speaker codebook, injected through adaptive instance normalization, which provides frame-aligned phonetic conditioning without cross-attention layers.
What would settle it
Take a trained model and condition it on a reference frame whose lips are visibly speaking a different utterance than the target audio; if the output reproduces the reference mouth rather than tracking the new audio, the 'learn to ignore the reference lips' assumption is false. Alternatively, dub a video with its own original audio as the target: if the output is nearly identical to the input, the model may have learned to copy rather than to edit.
Extended reading notes
Core claim
The central claim is that conditioning a diffusion model on the original unmasked video frames, together with a frame-accurate speech representation, lets the model alter only the lip motion while faithfully preserving the rest of the visual scene. EdiDub achieves this with a training-time reference-frame selection scheme that prevents the degenerate copy solution, and with DDIM inversion at inference so that generation starts from a noise code that already encodes the original clip's structure. The paper demonstrates on LRS2, LRS3, and two VoxCeleb2-derived benchmarks that this editing formulation achieves lower lip-sync error, higher sync confidence, and better identity preservation than generation- and inpainting-based baselines, especially when the mouth area is partially occluded.
Load-bearing premise
The central assumption is that training with a same-identity reference frame whose lips do not match the audio teaches the model to ignore that reference's mouth motion while still using its spatial details, and that this behavior transfers to inference, where the reference is the original video frame itself.
Editorial extensions
If this is right
- Dubbing can preserve scene elements such as hands covering the mouth, motion blur, and lighting variations that inpainting methods erase.
- Identity preservation and lip synchronization need not be strongly opposing objectives when the model is anchored to the original video through conditioning and inversion.
- A single-speaker audio codebook combined with the known audio-to-video frame alignment is sufficient to drive accurate articulation, removing the need for costly cross-attention.
- On the LRS3 benchmark, the method's audio-visual synchronization metrics are on par with real recordings, suggesting the task is nearing a perceptual ceiling for that dataset.
Reading between the lines
- The reference-frame selection principle implies that any conditioning signal carrying the same identity but different mouth motion could substitute for the original frame, so the method might extend to dubbing videos that have no clean reference frame of the speaker.
- The same content-aware editing formulation could transfer to other face-region edits, such as changing expression or apparent age while leaving the rest of the frame untouched; the paper does not explore this.
- The ablation shows a clear faithfulness-versus-articulation trade-off when inversion or reference selection is removed, suggesting the guidance scale or inversion strength could be a user-facing dial for that trade-off, which the paper leaves implicit.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes EdiDub, a two-stage diffusion system for visual dubbing. The first stage (LSD) edits a 64x64, 25-frame clip by masked diffusion conditioned on the full original video plus quantized HuBERT speech units, using DDIM inversion and MultiDiffusion for long videos; the second stage (SRD) restores 224x224 detail. The claimed contribution is reformulating dubbing as content-aware editing, rather than generation or inpainting, in order to preserve occlusions, lighting, and identity while changing only articulatory lip motion. The evaluation compares with Wav2Lip, DiffDub, and LatentSync on LRS2, LRS3, and two new VoxCeleb2 benchmarks (front-facing and occluded), reporting lip-sync metrics (LSE-D/C), two identity metrics (ID-P/ID-TC), MOS ratings with standard errors, and ablations of inversion, reference selection, and HuBERT clustering.
Significance. The task is practically important and the method is broadly sound in its engineering: paired Wilcoxon tests are reported, the MOS protocol includes quality-control screening, the occluded-lip benchmark is a useful new resource, and the architectural hyperparameters are concrete enough to re-implement. If the 'content-aware editing' claim can be supported by direct measurements, the paper would be a meaningful advance over inpainting-style dubbing, particularly for occluded and in-the-wild content. As submitted, however, the evidence does not yet close the gap between the central claim and the reported metrics, so the significance is conditional on the additional measurements requested below.
major comments (5)
- [§4.1, Table 3, Fig. 1] The central claim that EdiDub performs faithful content-aware editing rather than copying (Abstract, §1) is not directly supported by any reported metric. ID-P is a whole-face cosine distance between embeddings of original and generated frames; a no-op that returns the original video achieves ID-P near zero by construction, and MOS-Nat also rewards an unmodified original. The unique selling point on Vox2-Occluded is preservation of hand/object occlusions over the lips, but neither ID-P nor MOS-Nat measures whether the occlusion is retained; the qualitative claim in Fig. 1 is not quantified. The ablations in Table 3 even show that removing DDIM inversion or optimized reference selection improves LSE-D/LSE-C while degrading ID-P, which is consistent with the hypothesis that higher ID-P reflects copying more of the original rather than content-aware editing. A no-op baseline (dubbing with the original audio) and a region-wise fidelity metric restricted to non-articulatory areas are needed to separate context preservation from copy behavior. Without these, the abstract's contrast with inpainting is not established.
- [§3.2] The SRD input at inference is not fully specified. The text states that at each denoising step SRD receives a concatenated tensor containing 'the masked high-resolution ground-truth frames' yGT_0 together with the upsampled low-resolution reference, and that only the low-resolution component is replaced by the LSD output at inference. Since no ground truth exists at inference, this description is either a typo or implies that the original high-resolution frames (with the edited region masked) are used as context. If the latter is intended, it should be stated explicitly; as written, the final 224x224 stage is not reproducible from the description and appears ill-posed.
- [§3.1, Eq. (2)] The DDIM inversion update in Eq. (2) is not the standard DDIM inversion step. Standard inversion is an approximate reverse of the forward process and involves a ratio of alpha terms and an additive noise term involving epsilon_theta; Eq. (2) as written resembles a deterministic denoising update with the time index shifted rather than an inversion. Because DDIM inversion is a core component of the claimed editing behavior and is used in all reported results, the formula must be corrected or its notation justified, and the effect of using this approximate inversion should be discussed.
- [§3.1, 'Accurate visual reference'] The training reference strategy rests on an unmeasured transfer assumption. During training the model is conditioned on a same-identity reference frame at least five frames away so that it must ignore reference lip position, while at inference it is conditioned on the original video frame itself, whose lips are misaligned with the target audio. If the model over-relies on the reference lips, it copies the original misaligned mouth and lip-sync metrics improve spuriously; if it suppresses the conditioning too much, occlusions and context are lost. The paper does not test this transfer directly, and the ablations in Table 3 only vary the reference selection strategy, not the conditioning content at inference. A diagnostic that measures how strongly the model's output lip region correlates with the input/reference lip region, or a comparison against a model trained with the inference-time conditioning protocol, would make the central mechanism credible.
- [§3, first paragraph; Abstract] The first sentence of §3 says 'Both stages are trained as masked video inpainting problems.' This directly undercuts the Abstract's claim that the method 'reformulates visual dubbing as a content-aware editing task' and the Introduction's contrast with inpainting. The distinction is not merely rhetorical: if the training objective and mask-based diffusion are those of inpainting, the paper should state specifically what makes inference 'editing' beyond conditioning on the original video, and the evaluation should measure the additional property it claims. Please either revise the framing or add the missing measurement.
minor comments (6)
- [§4.4] The first sentence says 'Our method receives the highest MOS-Sync and MOS-Sync scores across all datasets'; the second score should be MOS-Nat.
- [§4.1 vs Appendix C.2] Section 4.1 says Vox2-Front clips have facial orientations within ±25 degrees from frontal, but Appendix C.2 and Algorithm 1 reject videos with a pose score exceeding 20 degrees; these thresholds should be reconciled.
- [Appendix A.1] In the 'Real Videos' rows, ID-P is 0.000 by construction because the original video is compared with itself, so it is not a meaningful anchor for the claim that a method is 'closest to real videos'; this caveat should be stated where the comparison is made in Section 4.3.
- [§4.2] The long-video stitching description ('Each section is generated sequentially, with the leading 12 frames from the end of the previous section with no mask (mask of zeros)') is unclear; please specify which frames are conditioned and which are generated when sections overlap.
- [Appendix B, Table 6] The SRD entries 'Masked MSE (MMSE) | MSE' and 'Mask lower-face area | None' conflict with the statement in §3.2 that SRD is trained with the same masked-reconstruction loss as LSD; the table and text should be aligned.
- [§4.1 and Appendix B] The paper says the code 'will be made available in the supplementary material' (Section 4.1) and also that it 'will be added as soon as possible' to an anonymous repository (Appendix B); the exact availability status should be stated in the final version.
Circularity Check
No significant circularity: EdiDub is an empirical learned system; its identity-preservation metric can reward copying, but that is an evaluation limitation, not a by-construction derivation.
full rationale
The paper does not derive a law or fit a parameter and then rename it as a prediction; it trains a conditional diffusion model and evaluates it on external benchmarks. The DDIM-inversion step (Eq. 2) is a standard invert-then-denoise editing heuristic, and the statement that it preserves non-lip content is an empirical assumption, not a consequence of the equation by construction. The reference-frame selection scheme is a training strategy; at inference the model sees the original video, so low ID-P could in principle be achieved by copying, but the paper also reports external LSE-D/C and human MOS, and the ablations (Table 3) show that removing the identity-anchoring components degrades ID-P while improving LSE, so the headline results are not forced solely by the conditioning input. There are no load-bearing self-citations, no imported uniqueness theorem, and no fitted constant presented as a prediction; the references cited for HuBERT clustering, DDIM inversion, and MultiDiffusion are external. The main flagged concern is internal consistency rather than circularity: Section 3 states 'Both stages are trained as masked video inpainting problems,' which undercuts the Abstract's contrast with inpainting, and the claimed preservation of occlusions on Vox2-Occluded is not directly quantified. These are evaluation and novelty limitations, not circular derivation steps.
Assumptions & free parameters
free parameters (6)
- HuBERT codebook size =
k=200
- Classifier-free guidance scale =
s=5
- DDIM steps =
T=50
- MultiDiffusion window and step =
24-frame window, 12-frame step
- Reference exclusion window =
±5 frames
- Mask region =
below the eyes
assumptions (4)
- domain assumption HuBERT features quantized with a single-speaker LJ-Speech codebook remove speaker identity and preserve phonetic content.
- ad hoc to paper Training with reference frames from the same identity teaches the model to ignore reference lip movement while using spatial context, and this transfers to inference with original-video conditioning.
- standard math DDIM inversion reconstructs the original video's structure faithfully when conditioning on original speech, so editing with new speech preserves context.
- domain assumption The 25-frame and 5-frame training windows, and the LRS3 training set, are sufficient to generalize to the four evaluation benchmarks.
Cite this review
Pith. "Pith review of Video Editing for Audio-Visual Dubbing." pith.science (2026). https://pith.science/paper/4GP6BYDI
@misc{pith2026250523406,
author = {Pith},
title = {Pith review of: Video Editing for Audio-Visual Dubbing},
year = {2026},
howpublished = {\url{https://pith.science/paper/4GP6BYDI}},
note = {Machine review of arXiv:2505.23406}
}
read the original abstract
Visual dubbing, the synchronization of facial movements with new speech, is crucial for making content accessible across different languages, enabling broader global reach. However, current methods face significant limitations. Existing approaches often generate talking faces, hindering seamless integration into original scenes, or employ inpainting techniques that discard vital visual information like partial occlusions and lighting variations. This work introduces EdiDub, a novel framework that reformulates visual dubbing as a content-aware editing task. EdiDub preserves the original video context by utilizing a specialized conditioning scheme to ensure faithful and accurate modifications rather than mere copying. On multiple benchmarks, including a challenging occluded-lip dataset, EdiDub significantly improves identity preservation and synchronization. Human evaluations further confirm its superiority, achieving higher synchronization and visual naturalness scores compared to the leading methods. These results demonstrate that our content-aware editing approach outperforms traditional generation or inpainting, particularly in maintaining complex visual elements while ensuring accurate lip synchronization.
Figures
Reference graph
Works this paper leans on
-
[1]
What is the McGurk effect?Frontiers in psychology, 2014
Kaisa Tiippana. What is the McGurk effect?Frontiers in psychology, 2014
work page 2014
-
[2]
Denoising diffusion probabilistic models.Advances in neural information processing systems, 33:6840–6851, 2020
Jonathan Ho, Ajay Jain, and Pieter Abbeel. Denoising diffusion probabilistic models.Advances in neural information processing systems, 33:6840–6851, 2020
2020
-
[3]
Shuai Tan, Bin Ji, and Ye Pan. FlowVQTalker: High-quality emotional talking face generation through normalizing flow and quantization. InProceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR), pages 26317–26327, 2024
work page 2024
-
[4]
Diffused heads: Diffusion models beat GANs on talking-face generation
Michał Stypułkowski, Konstantinos V ougioukas, Sen He, Maciej Zi˛ eba, Stavros Petridis, and Maja Pantic. Diffused heads: Diffusion models beat GANs on talking-face generation. In Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision (WACV), pages 5091–5100, 2024
work page 2024
-
[5]
EmoTalker: Emotionally editable talking face generation via diffusion model
Bingyuan Zhang, Xulong Zhang, Ning Cheng, Jun Yu, Jing Xiao, and Jianzong Wang. EmoTalker: Emotionally editable talking face generation via diffusion model. InIEEE Interna- tional Conference on Acoustics, Speech and Signal Processing (ICASSP), pages 8276–8280, 2024. 9
work page 2024
-
[6]
Chunyu Li, Chao Zhang, Weikai Xu, Jinghui Xie, Weiguo Feng, Bingyue Peng, and Weiwei Xing. LatentSync: Audio conditioned latent diffusion models for lip sync.arXiv preprint arXiv:2412.09262, 2024
arXiv 2024
-
[7]
A lip sync expert is all you need for speech to lip generation in the wild
KR Prajwal, Rudrabha Mukhopadhyay, Vinay P Namboodiri, and CV Jawahar. A lip sync expert is all you need for speech to lip generation in the wild. InProceedings of the 28th ACM international conference on multimedia, pages 484–492, 2020
2020
-
[8]
DiffDub: Person-generic visual dubbing using inpainting renderer with diffusion auto-encoder
Tao Liu, Chenpeng Du, Shuai Fan, Feilong Chen, and Kai Yu. DiffDub: Person-generic visual dubbing using inpainting renderer with diffusion auto-encoder. InIEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pages 3630–3634, 2024
work page 2024
Show all 38 references
-
[9]
Denoising diffusion implicit models.arXiv preprint arXiv:2010.02502, 2020
Jiaming Song, Chenlin Meng, and Stefano Ermon. Denoising diffusion implicit models.arXiv preprint arXiv:2010.02502, 2020
2010 arXiv
-
[10]
Hubert: Self-supervised speech representation learning by masked prediction of hidden units.IEEE/ACM transactions on audio, speech, and language processing, 29:3451–3460, 2021
Wei-Ning Hsu, Benjamin Bolte, Yao-Hung Hubert Tsai, Kushal Lakhotia, Ruslan Salakhutdinov, and Abdelrahman Mohamed. Hubert: Self-supervised speech representation learning by masked prediction of hidden units.IEEE/ACM transactions on audio, speech, and language processing, 29:3...
2021
-
[11]
Video diffusion models.Advances in Neural Information Processing Systems, 35:8633–8646, 2022
Jonathan Ho, Tim Salimans, Alexey Gritsenko, William Chan, Mohammad Norouzi, and David J Fleet. Video diffusion models.Advances in Neural Information Processing Systems, 35:8633–8646, 2022
2022
-
[12]
Cascaded diffusion models for high fidelity image generation.Journal of Machine Learning Research, 23(47):1–33, 2022
Jonathan Ho, Chitwan Saharia, William Chan, David J Fleet, Mohammad Norouzi, and Tim Salimans. Cascaded diffusion models for high fidelity image generation.Journal of Machine Learning Research, 23(47):1–33, 2022
2022
-
[13]
V oxceleb2: Deep speaker recognition
Joon Son Chung, Arsha Nagrani, and Andrew Zisserman. V oxceleb2: Deep speaker recognition. arXiv preprint arXiv:1806.05622, 2018
2018 arXiv
-
[14]
Stylesync: High-fidelity generalized and personalized lip sync in style-based generator
Jiazhi Guan, Zhanwang Zhang, Hang Zhou, Tianshu Hu, Kaisiyuan Wang, Dongliang He, Haocheng Feng, Jingtuo Liu, Errui Ding, Ziwei Liu, et al. Stylesync: High-fidelity generalized and personalized lip sync in style-based generator. InProceedings of the IEEE/CVF Conference on Comp...
2023
-
[15]
Analyzing and improving the image quality of stylegan
Tero Karras, Samuli Laine, Miika Aittala, Janne Hellsten, Jaakko Lehtinen, and Timo Aila. Analyzing and improving the image quality of stylegan. InProceedings of the IEEE/CVF conference on computer vision and pattern recognition, pages 8110–8119, 2020
2020
-
[16]
Diff2lip: Audio conditioned diffusion models for lip-synchronization
Soumik Mukhopadhyay, Saksham Suri, Ravi Teja Gadde, and Abhinav Shrivastava. Diff2lip: Audio conditioned diffusion models for lip-synchronization. InProceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision, pages 5292–5302, 2024
2024
-
[17]
High- resolution image synthesis with latent diffusion models
Robin Rombach, Andreas Blattmann, Dominik Lorenz, Patrick Esser, and Björn Ommer. High- resolution image synthesis with latent diffusion models. InProceedings of the IEEE/CVF conference on computer vision and pattern recognition, pages 10684–10695, 2022
2022
-
[18]
The LJ speech dataset
Keith Ito and Linda Johnson. The LJ speech dataset. https://keithito.com/ LJ-Speech-Dataset/, 2017
2017
-
[19]
Revise: Self-supervised speech resynthesis with visual input for universal and generalized speech regeneration
Wei-Ning Hsu, Tal Remez, Bowen Shi, Jacob Donley, and Yossi Adi. Revise: Self-supervised speech resynthesis with visual input for universal and generalized speech regeneration. In Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition, pages 18795–18...
2023
-
[20]
Arbitrary style transfer in real-time with adaptive instance normalization
Xun Huang and Serge Belongie. Arbitrary style transfer in real-time with adaptive instance normalization. InProceedings of the IEEE International Conference on Computer Vision (ICCV), pages 1501–1510, 2017
2017
-
[21]
Classifier-free diffusion guidance.arXiv preprint arXiv:2207.12598, 2022
Jonathan Ho and Tim Salimans. Classifier-free diffusion guidance.arXiv preprint arXiv:2207.12598, 2022. 10
2022 arXiv
-
[22]
Multidiffusion: Fusing diffusion paths for controlled image generation
Omer Bar-Tal, Lior Yariv, Yaron Lipman, and Tali Dekel. Multidiffusion: Fusing diffusion paths for controlled image generation. 2023
2023
-
[23]
Lip reading sentences in the wild
Joon Son Chung, Andrew Senior, Oriol Vinyals, and Andrew Zisserman. Lip reading sentences in the wild. InProceedings of the IEEE conference on computer vision and pattern recognition (CVPR), pages 6447–6456, 2017
2017
-
[24]
LRS3-TED: A large-scale dataset for visual speech recognition.arXiv preprint arXiv:1809.00496, 2018
Triantafyllos Afouras, Joon Son Chung, and Andrew Zisserman. LRS3-TED: A large-scale dataset for visual speech recognition.arXiv preprint arXiv:1809.00496, 2018
2018 arXiv
-
[25]
Flow-guided one-shot talking face generation with a high-resolution audio-visual dataset
Zhimeng Zhang, Lincheng Li, Yu Ding, and Changjie Fan. Flow-guided one-shot talking face generation with a high-resolution audio-visual dataset. InProceedings of the IEEE/CVF conference on computer vision and pattern recognition, pages 3661–3670, 2021
2021
-
[26]
ModeFormer: Modality-preserving embed- ding for audio-video synchronization using transformers
Akash Gupta, Rohun Tripathi, and Wondong Jang. ModeFormer: Modality-preserving embed- ding for audio-video synchronization using transformers. InIEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), pages 1–5, 2023
2023
-
[27]
Learning transferable visual models from natural language supervision
Alec Radford, Jong Wook Kim, Chris Hallacy, Aditya Ramesh, Gabriel Goh, Sandhini Agarwal, Girish Sastry, Amanda Askell, Pamela Mishkin, Jack Clark, et al. Learning transferable visual models from natural language supervision. InInternational Conference on Machine Learning (ICM...
2021
-
[28]
J. S. Chung and A. Zisserman. Out of time: Automated lip sync in the wild. InWorkshop on Multi-view Lip-reading, ACCV, 2016
2016
-
[29]
facenet-pytorch.https://github.com/timesler/facenet-pytorch, 2022
Tim Esler. facenet-pytorch.https://github.com/timesler/facenet-pytorch, 2022
2022
-
[30]
Decoupled weight decay regularization.arXiv preprint arXiv:1711.05101, 2017
Ilya Loshchilov and Frank Hutter. Decoupled weight decay regularization.arXiv preprint arXiv:1711.05101, 2017
2017 arXiv
-
[31]
Wilcoxon signed-rank test.Encyclopedia of biostatistics, 8, 2005
Robert F Woolson. Wilcoxon signed-rank test.Encyclopedia of biostatistics, 8, 2005
2005
-
[32]
Diffusion models beat gans on image synthesis
Prafulla Dhariwal and Alexander Nichol. Diffusion models beat gans on image synthesis. Advances in neural information processing systems, 34:8780–8794, 2021
2021
-
[33]
guided-diffusion.https://github.com/openai/guided-diffusion, 2021
OpenAI. guided-diffusion.https://github.com/openai/guided-diffusion, 2021
2021
-
[34]
Improved denoising diffusion probabilistic models
Alexander Quinn Nichol and Prafulla Dhariwal. Improved denoising diffusion probabilistic models. InInternational conference on machine learning, pages 8162–8171. PMLR, 2021
2021
-
[35]
ns" represents non-significant results (p > 0.05),
google-ai edge. mediapipe.https://github.com/google-ai-edge/mediapipe, 2025. 11 A Extended Results In this section, we provide a deeper look into the results of our experiments, including statistical tests, our MOS web page, and our MOS results analysis process. All the videos...
2025
-
[36]
We used a constant crop to ensure the corrupted video would not inadvertently synchronize with the audio
Replacing the mouth region with a constant crop from a different frame, updating this crop once every 25 frames. We used a constant crop to ensure the corrupted video would not inadvertently synchronize with the audio
-
[37]
Rotating the inserted crop by 180 degrees
-
[38]
facebook/hubert-large-ll60k
Adding unique Gaussian noise (mean 0, standard deviation 20) to the pasted region in every frame. These distortions were deliberately applied only after the first 15 frames and terminated 5 frames before the end, ensuring that participants needed to watch a significant portion...
Reviewed August 7, 2026 · model on record in the stance chip above.
Discussion (0). Sign in to comment.