Lecture 10: Multimodal LLMs

Can large models see, hear, speak, act — and understand 3D space? Watch the lecture in nine short chapters with English and Chinese subtitles, follow the lecture map below, then try the ideas in Colab.

📅 Nov. 27th, 2026 🎥 9 chapters · 107 min 🖼 134 slides 💬 EN + 中文 subtitles 🧭 Lecture map 💻 Colab notebooks ⬇ Slides (PDF)
Transcript follows the video · click a sentence to jump · Shift + ←/→ jumps between slides

1The lecture map

How do we give a language model eyes, ears, a voice and hands — and a sense of space?

Five acts, nine chapters. The model first learns to see, then to hear, speak and create, then to act in a 3D world — and through all of it, language stays the hub that connects the modalities. Click a chapter to watch it.

IWhy
Why text alone is not enough
IISee
Match images to text, then read them
IIIHear, speak & create
Talk in real time; create images and video
IVAct in 3D
Turn perception into action in space
VNext
What is still open
Chapter by chapter what each chapter covers, and the question it leaves for the next
  1. IWhyWhy text alone is not enough
  2. 1

    Why Multimodality?

    Humans perceive through many senses at once, the web is multimodal, and high-quality text is running out.

    → Can a model perceive the world the way we do?
  3. IISeeMatch images to text, then read them
  4. 2

    Connecting Vision and Language: CLIP and Flamingo

    CLIP puts images and text in one space by contrastive learning, which gives zero-shot recognition and retrieval. Flamingo lets a frozen LLM read images through a Perceiver Resampler and gated cross-attention.

    → Matching and few-shot reading work — but how should a general model be built?
  5. 3

    Multimodal LLMs: Architecture

    Language is the pivot. The LLM either controls expert tools, or vision becomes part of the model (encoder + connector + LLM, as in LLaVA and Qwen-VL), up to native models such as GPT-4o and Gemini.

    → The architecture is set — what data teaches it?
  6. 4

    Training Multimodal LLMs

    Stage 1 aligns image features with the LLM on captions; stage 2 tunes it on visual instructions, often written with GPT's help.

    → Images work — what about sound?
  7. IIIHear, speak & createTalk in real time; create images and video
  8. 5

    Speech Language Models

    Speech is long, continuous and rich in tone. Turn it into tokens, interleave them with text, listen while speaking, and split the work between a thinker and a talker.

    → The model can understand and talk — can it also create?
  9. 6

    Generation and World Simulators

    Unify understanding and generation, predict the next frame, and use video models as simulators of the world.

    → Is a generated world physically right — and can a model act in it?
  10. IVAct in 3DTurn perception into action in space
  11. 7

    Embodied Intelligence: VLA and World Models

    Vision-language-action models map pixels and instructions to motor commands: System 2 plans while System 1 acts, and world-action models predict both the future and the action.

    → Acting needs space — what do pictures miss?
  12. 8

    3D Understanding and Generation

    Images are only projections. Feed-forward 3D reconstruction, 3D generation, and an LLM that writes scene graphs.

    → What is still open?
  13. VNextWhat is still open
  14. 9

    Research Directions and Outlook

    Efficiency, evaluation, more modalities, edge devices — and what changed in 2026.

2Try it in Colab

Three short notebooks turn the lecture into experiments. Click Open in Colab, then Runtime → Run all. Each ends with exercises. Notebook 2 needs a free T4 GPU (Runtime → Change runtime type); the others also run on CPU.

Notebook 1 · Chapter 2 · ~5 min

CLIP: zero-shot classification and retrieval

  • Classify images into labels CLIP never trained on
  • See a prompt raise P(cat) from 0.24 to 0.69
  • Search images with text, and find where it fails
  • Compute the contrastive loss by hand
Open in Colab .ipynb · CPU or GPU
Notebook 2 · Chapters 3–4 · ~10 min

Chat with an open multimodal LLM

  • Ask Qwen2.5-VL-3B about images, alone or several at once
  • Count how many tokens an image becomes
  • Find the vision encoder, connector and LLM inside the model
Open in Colab .ipynb · T4 GPU
Notebook 3 · Chapter 5 · ~5 min

Speech as tokens

  • Compress speech with a neural codec and listen at 1.5–12 kbps
  • Check with Whisper whether the words survive
  • See that speech needs ~160× more tokens than its transcript
Open in Colab .ipynb · CPU or GPU

3Concept index

Key terms of the lecture. Each link opens the video at the slide where the idea is explained.

5Quotes & reading

"The limits of my language mean the limits of my world."

Ludwig Wittgenstein, Tractatus 5.6 (1921)
The case for language as the hub — and for giving it more of the world to describe.

"Language is an imperfect, incomplete, and low-bandwidth serialization protocol for the internal data structures we call thoughts."

Why text alone is not enough.

"If we want machines to think, we need to teach them to see."

Fei-Fei Li, TED (2015)
The motivation behind ImageNet, and behind Chapters 2–4.

"What I cannot create, I do not understand."

Richard Feynman, on his blackboard (1988)
Why generation and world simulators (Chapter 6) test understanding.

Further reading

6About this video

This is an AI-narrated version of the lecture. The slides are the ones used in class. The spoken script was written from the slides with AI assistance and is read in an AI clone of Prof. Benyou Wang's voice (MiniMax speech synthesis); the picture in the corner is a still photo. The red dot points at what is being discussed. When the narration and the slides disagree, trust the slides and the in-class lecture — and please tell us, so we can fix it.
CSC5051/CSC6052/MDS5110 Natural Language Processing · CUHK-Shenzhen · Fall 2026 · Back to the course page