AI Video Generation: A Guide to Runway, Pika, and Sora

Imagine this: you just need to input a text description, and AI can generate a realistic video. This was science fiction two years ago, but now it's reality. Text-to-Video is the most exciting direction in the field of AI video.

Comparison of Mainstream Text-to-Video Tools

Runway Gen-3 Alpha

Currently the most stable text-to-video tool for commercial use. Advantages: Stable generation quality, supports image-to-video and video extension, has a complete editing interface. Disadvantages: Higher price (starting at $12/month), generates 5-10 seconds per clip. Suitable for professional users pursuing quality and stability.

Pika

Known for its stylization and creativity. Advantages: Rich style choices, simple operation, moderate price. Disadvantages: Realistic video quality is not as good as Runway's. Suitable for creative social media content and videos with artistic styles.

Sora (OpenAI)

A video generator launched by OpenAI, capable of generating videos up to 60 seconds long. Advantages: Longest video duration, strong scene understanding. Disadvantages: Requires a ChatGPT Plus subscription, slower generation speed. Suitable for scenarios requiring longer continuous shots.

Kling (Kuaishou) / Vidu (Shengshu Technology)

AI video generation tools directly accessible in China. Advantages: No need for VPN, Chinese interface, better understanding of Chinese cultural scenes. Suitable for domestic users and content creation related to Chinese culture.

Prompt Writing Techniques

The quality of text-to-video largely depends on your prompt. Here are the core techniques:

Describe the Visual Content

Specifically describe the scene you want: what is the subject, what are they doing, what is the background. "A girl reading under a cherry blossom tree" is much better than "a person outside."

Specify the Visual Style

Cinematic, animation style, documentary style, slow motion, aerial shot—clearly state your desired visual style. You can reference specific film or photography styles, such as "cinematic quality, shallow depth of field, warm-toned lighting."

Describe Camera Movement

The camera's movement greatly affects video quality: "slow push-in," "orbital shot," "low-angle upward shot," "aerial overhead shot"—these descriptions help AI generate more cinematic shots.

Control Time and Pace

"Slow motion," "time-lapse," "quick cuts"—describe your desired temporal rhythm, and AI will adjust the video's speed and pacing accordingly.

Image-to-Video Techniques

Besides generating video purely from text, you can also upload an image and have AI generate a dynamic video based on it. This method offers stronger control over the visuals. Workflow: First, generate a satisfactory image using Midjourney/Stable Diffusion, then convert it into video using Runway/Pika.

Practical Application Scenarios

Currently, the most practical scenarios for AI-generated video include: rapid prototyping for advertising concepts (using AI to validate ideas before formal shooting), supplementing social media materials (generating transitions, backgrounds, and atmospheric elements), product showcase videos (especially for conceptual products and effect demonstrations), and educational/training content (visualization of abstract concepts).

AI-generated video will not replace traditional video production, but it is becoming an indispensable part of every video creator's toolkit. The sooner you master it, the greater your advantage in content competition.

Congratulations on completing the free chapter on AI video production! The full course will delve into AI digital human creation, commercial video workflows, AI video monetization strategies, and industry case studies.

Before AI painting emerged, creating a high-quality image might have taken a professional designer hours or even days. Now, you just need to input a text description, and AI can generate a stunning image in tens of seconds. This isn't magic; it's the power of Diffusion Models.

Basic Principles of AI Image Generation

You don't need to understand complex math, just the core concept: AI image generation models learn from billions of images and their corresponding text descriptions, establishing associations between "text" and "visual elements." When you input "a seaside castle at sunset, watercolor style," AI breaks down this text into multiple visual concepts (sunset, seaside, castle, watercolor) and then "blends" these concepts to generate a brand new image.

Key Concept: AI does not search and stitch images from the web; it "creates" entirely new images based on learned visual patterns. Each generated result is unique.

Mainstream AI Painting Tools

Midjourney

Currently the AI painting tool with the best overall experience. Advantages: Extremely high image quality, rich artistic styles, active community. Disadvantages: Requires use via Discord (has a web version but experience is inferior), paid subscription (starting at $10/month), requires VPN. Most suitable for users pursuing high-quality artistic images.

Stable Diffusion

An open-source AI painting model that can run on a local computer. Advantages: Completely free, highly customizable, supports various plugins and fine-tuned models (LoRA). Disadvantages: Requires certain computer specs (recommended GPU with 8GB+ VRAM), higher learning curve. Most suitable for users needing batch generation or deep customization.

DALL-E 3 (Integrated in ChatGPT)

OpenAI's image generation model. Advantages: Directly usable via ChatGPT, good conversational generation experience, easy to modify. Disadvantages: Style leans towards illustrations and concept art, realistic quality not as good as Midjourney. Suitable for quickly generating concept art and supporting images.

Domestic Tools

**Tongyi Wanxiang** (Alibaba) and **ERNIE Bot Art** (Baidu) are AI painting tools directly usable in China. Advantages: No VPN needed, support for Chinese prompts, have free quotas. Suitable for domestic users to get started and experience.

What You Can Do with AI Painting

Commercial scenarios include: social media images and covers, product concept design and renderings, brand visual assets, e-commerce product main images, blog/article illustrations, and presentation graphics. Personal scenarios include: wallpaper and avatar generation, artistic creation and exploration, gift customization (e.g., AI-generated cards).

Copyright and Ethics

The copyright issue of AI-generated images is currently under discussion worldwide. General principle: Using AI-generated images for personal projects and social media content is usually safe; for commercial use, it's recommended to use tools with explicit commercial licenses (e.g., Midjourney paid plan); avoid generating images imitating a specific artist's style for commercial purposes.

After understanding the basics of AI painting, the next chapter will dive into Midjourney practice—systematically mastering prompt techniques to enable you to consistently generate high-quality images.