Shadowing Practice: SANA-Video: Efficient Video Generation with Block Linear Diffusion Transformer, [ICLR 2026, Oral] - Learn English Speaking with Video

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Thank you, Luke, for the amazing opening.

So good morning and thanks for having me.

My name is Jun Song.

I'm from the University of Hong Kong and NVIDIA.

It's really my great honor to present this work, SANA Video, for our SANA team.

So currently, generative AI is evolving rapidly with model sizes growing larger and larger.

At At the same time, AVIDIA GPUs are becoming increasingly powerful.

We can foresee that the future visual generative models will demand even more computational resources.

So actually, generating images and videos are significantly more computationally demanding than processing just text.

For example, the inference for Flux or CogVideoX exceed the Lama 3,

and an order of magnitude higher than the VIT models.

So they are restricted to cloud deployment and remain impractical for consumer GPUs or age devices.

So actually, efficiency is a forever topic.

So far, we have explored several directions for efficient video generation.

First, in Sanaa, we tried to reduce input tokens by using our self -developed deep compression autoencoder, DCAE.

We also try to use linear tension to replace Softmax 1, enhance the architectural efficiency of the model.

And we also already explored inference step distillation in Sanaa's spring project.

The fewer the inference steps, the faster the speed.

So the last part is what we are going to talk about today, the hybrid AR plus diffusion for long video generation.

Actually, we can generate video block by block causally and diffuse within the block.

So video generation requires much more computation than images.

SANA can generate one image within just one second.

However, generating a five -second video with one model actually takes nearly 30 minutes.

So to boost the video generation efficiency, we focus on three key technical areas, the high ratio VAEs and leaning attention mechanisms,

especially optimized for video tasks.

Crucially, the block KV cache based on leaning attention enables the generation of much longer videos.

So to get a video generation model, actually, we have two ways to go to try to choose.

First, we can just train from scratch.

But only when we have hundreds or thousands of GPUs,

like H100 GPUs, and it will take you almost several months to train one model.

And it's, of course, not affordable.

Or actually, we can start from a semantic aligned text -to -image model.

Here we start from our SANA 1 .5, which is a 1 .6 billion parameter text -to -image model trained on our DCAE.

Actually, since our video model is based on image model, so the linear tension DIT actually is almost the same as our SANA,

but we're introducing two modules for temporal modeling, and we will talk about them later.

Finally, on the left at the top, we implement block causal linear tension module to achieve constant kv cache memory.

So for any length video generation, So first, let's talk about linear attention in video generation model.

Actually, in video tasks, linear attention provides even more significant acceleration than in images,

as the video length and resolution are much larger.

Our results show that for long videos, SANA video is 1 .5 times faster than the one model.

And additionally, at high resolution, our linear attention is four times faster than the flash attention.

And these improvements make a long form, high resolution video generation much more practical.

However, we find that the linear attention map is far different from the softmax attention.

As you can see in this figure, the linear attention is super dense, while the softmax attention is rather sparse.

And this demonstrates that the local contacts captured by the linear tension is actually insufficient.

To enhance the temporal modeling, we introduced two key improvements.

First is the 3D rope for the linear tension and temporal convolutions.

And both are highlighted in the orange box.

While 3D rope doesn't solve the tension map sparsity problem entirely, it do help improve attention low quality.

Combined with our spatial temporal mix FFN, it significantly boosts the overall performance.

Here we have the training loss.

The green line stands for the 3D rope and the additional temporal convolution.

And to further support long video generation, we leverage the unique properties of linear attention to implement an efficient block KV cache.

So let's quickly review how this works.

In linear attention, we call it the attention map, or the state.

Actually, it has a fixed shape of D times D, regardless of the input sequence length.

So when processing the first block here, we obtain the state, S1.

And for the second block, the state is updated additably,

meaning that we only need to add the current block's contribution to the previous cache.

And generally for any block I,

actually the current state is updated as adding the current block contribution the KV here to the previous cache to ask.

So now let's see how we enable long video generation with block of causal linear attention.

For the first block here, the green one, we compute the state as one, shown in the green box.

After we compute first block the state, we cache it, it's shown in the red box.

Then we calculate the KV for the next block and add it to the previous one.

Here we take the cached state from block one in the red box and updates it into the block two, which is in the green color.

And the subsequent process follows the same logic.

The new state is cached, and once the next block competition is finished, they are summed together. And so on.

So, token in Valenian attention will become larger, more and more as the video length become larger and larger.

While our causal linear tension maintains a constant KV cache potentially make minute length video generation possible.

So here in conclusion, we can have two advantages of block linear tension.

First, we have constant memory usage regardless of the input sequence length and second we have the global history context.

So one last question is how to achieve causal FFN with temporal conf.

So let's take two block situation as example.

During causal training the block one cannot foresee block two so we pad a zero token here between the two blocks.

However block two must see block one's token so that it's correct the causal modeling.

So here we catch the last token from block one as the first token in block two.

So finally the two blocks are separated by the zero padding token

which is subsequently removed to to avoid affecting the final computation.

And the block two used the last token from block one making the the causal modeling available.

So here's some results, compared to the current state -of -the -art video models, Sonar Video performs competitively on VBench,

and it takes only 18 seconds to generate a 1K resolution video on a single H100 GPU.

Here we show some examples.

On the left we have text to video examples, And on the right, we show the image to video examples.

And using SANA video as a base model, it can be applied to tasks like physical AI and real -world models.

Actually, by fine -tuning SANA video on a small data site with just a few safety steps,

we enable it to generate videos for robotic manipulation and gameplay play.

We also combine with the post -training tech in long lab, which is a three long test long method.

And this method is also accurate poster and is also from our group.

We also implement the DMD step distillation to further accelerate our model.

And finally, Sonar Video you can also generate minute -length video within just 36 seconds,

achieving 27 FPS real -time generation.

So, finally, there is one more thing.

Based on linear attention, we have much more potential applications to discover.

We believe the efficiency of linear attention

and deep compression auto encoder will facilitate streaming video generation

and also the development of long form like minute -length or even hour -length, real -world models.

And we are working on this project and we'll see if we can keep pushing the efficiency boundary.

And all of our projects, including the code and checkpoints,

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are all open -source to encourage further exploration in efficient generative AI system.

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So that's all for my talk today.

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And we will have a poster session right after this aural, maybe in the afternoon.

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Welcome everyone to discuss more.

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Thanks so much.

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Thank you.

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Time for a quick question, if any.

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Yeah, please go to the mic.

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Thank you for your speech, and I have a question.

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I think it's something similar to the auto -aggressive video diffusion models like cause of it

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and something similar to the block causal linear attention you introduced.

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So I wanted to ask what are the key differences and if we are thinking about infinite long video generation,

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which one do you think would be better choice?

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Thank you.

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Thank you for your question.

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Actually the cause V something like that, they actually perform on soft max extension.

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So as I talked before, the soft max extension has an open square computation complexity.

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So if you want to generate mini lens or even hour lens video, it's not possible to do it on soft max extension.

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So if you want to generate mini lens video, so you have to keep the computation within like a sliding window or something like that.

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So the main difference here is our linear tension has the global context.

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It has memory from the first second to the final second.

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So if you want to do some project or task like world model,

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it has to be maintaining overall all the cache or the memory.

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So I think that's the main advantages of getting attention.

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Yeah, thank you.

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Thank you.

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Vocabulary and speaking notes for this lesson

This speaking lesson is built on the video “SANA-Video: Efficient Video Generation with Block Linear Diffusion Transformer,”. The speaker keeps coming back to these words: block, attention, model, linear, generation. This video has 125 sentences and 1634 words to shadow. The speech runs for 12:46. The speaker talks at a steady 128 words per minute, a comfortable pace for shadowing. Only 80% of the words are among the 3,000 most common in English, so the vocabulary is demanding.

Key vocabulary in this video

15 words from the video worth learning, with pronunciation and meaning:

Word	Pronunciation	Meaning
linear adjective	/ˈlɪn.i.əɹ/	Having the form of a line; straight or roughly straight; following a direct course.
cache noun	/kæʃ/	Such a store of physical supplies, placed by humans or other animals for practical reasons.
generate verb	/ˈd͡ʒɛn.ə.ɹeɪt/	To bring into being; give rise to.
tension noun	/ˈtɛnʃən/	The condition of being held in a state between two or more forces, which are acting in opposition to each other.
token noun	/ˈtoʊkən/	Something serving as an expression of something else.
temporal adjective	/ˈtɛm.pə.ɹəl/	Of or relating to the material world, as opposed to sacred or clerical.
efficiency noun	/ɪˈfɪʃ.ən.si/	The extent to which a resource is used for the intended purpose.
extension noun	/ɪkˈstɛnʃən/	The act of extending; a stretching out; enlargement in length, breadth, or time; an increase.
efficient adjective	/ɪˈfɪʃənt/	Making good, thorough, or careful use of resources; not consuming extra. Especially, making good use of time or energy.
introduce verb	/ˌɪntɹəˈdus/	To cause (someone) to be acquainted (with someone else).
input noun	/ˈɪnpʊt/	The act or process of putting in; infusion.
enable verb	/ɪˈneɪ.bəl/	To make somebody able (to do, or to be, something); to give sufficient ability or power to do or to be; to give strength or ability to.
implement verb	/ˈɪmpləmənt/	To bring about; to put into practice; to carry out.
lens noun	/lɛnz/	An object, usually made of glass, that focuses or defocuses the light that passes through it.
rope noun	/ɹoʊp/	Thick strings, yarn, monofilaments, metal wires, or strands of other cordage that are twisted together to form a stronger line.

Grammar in this video

The structures the speaker uses most, with the exact words from the video:

Structure	In the video
Passive voice be + past participle — the focus is on what happens, not who does it	are restricted · is based · are highlighted
Relative clauses who / which + clause — extra information about a person or thing	two, which is · lab, which is

Pronunciation to watch

The speaker uses 4 contractions and reduced forms, such as doesn't, I'm, we'll. Say them the short way, as you hear them.

The “sh” and “zh” sounds: cache /kæʃ/, tension /ˈtɛnʃən/, efficiency /ɪˈfɪʃ.ən.si/, extension /ɪkˈstɛnʃən/, efficient /ɪˈfɪʃənt/
Long words — get the stress right: efficiency /ɪˈfɪʃ.ən.si/, contribution /ˌkɑntɹɪˈbjuʃən/, automobile /ˈɔː.tə.məˌbil/, potentially /pəˈtɛnʃ(ə)li/, mechanism /ˈmɛk.ə.nɪ.zəm/

How to practise with this video

Listen to the whole video once without speaking and note the words you do not know.
Shadow it sentence by sentence at normal speed, repeating each one until your rhythm matches the speaker.
Record yourself and compare with the original, paying attention to words like linear, cache, generate.

What is the Shadowing Technique?

Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.

Shadowing technique: read the full step-by-step guide →

Shadowing Practice: SANA-Video: Efficient Video Generation with Block Linear Diffusion Transformer, [ICLR 2026, Oral] - Learn English Speaking with Video

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Vocabulary and speaking notes for this lesson

Key vocabulary in this video

Grammar in this video

Pronunciation to watch

How to practise with this video

What is the Shadowing Technique?