AI Avatars: Lock Scripts, Avoid Omitted & Altered Lines

Preface

A common challenge in AI digital avatar videos is that AI automatically deletes or rewrites scripts, causing the final video dialogue to differ from the original script, making it difficult to use for product promotion videos.

After repeated testing with two different models, this tutorial provides a practical solution that preserves the complete script while maintaining natural lip synchronization and visual quality. It is suitable for English and various other foreign-language short videos.

Target Users

·Short video beginners

·Cross-border content creators

·Overseas product promotion influencers

Applicable Scenarios

Creating talking-head videos or promotional videos that require strict script accuracy and do not allow missing words, incorrect text, or unauthorized modifications.

Three Practical Rules You Must Remember Before Creating Videos

Based on actual testing, violating any one of these rules will highly likely cause script errors:

1.The number of words in a single shot should ideally be controlled within 80 words. Longer texts may cause AI recognition errors, so the content must be divided into multiple shots.

2.If you choose Gemini Omni for generation, you must include the dedicated script-locking sentence in the prompt. Missing even one part of the instruction may cause the AI to modify the dialogue.

3.Keep the entire prompt as short as possible. Avoid adding negative prompts unless necessary, because excessive text will reduce the priority of script recognition.

I. Quick Start Guide for Beginners (Create a Video in 5 Minutes)

Many beginners add too many visual descriptions at the beginning, which actually causes script errors. Follow this simple workflow:

1.Prepare the segmented script first and make sure each section contains no more than 80 words.

2.If there are no obvious distortions or flickering issues in the generated visuals, do not use negative prompts. Only add them temporarily when facial distortion occurs frequently.

3.Use the corresponding speaking sentence format based on the target language. There is no need to memorize fixed formats.

4.If script accuracy is the priority, choose Gemini Omni. If you only need natural lip synchronization and short dialogue, choose Seedance.

5.To maintain a consistent character appearance, upload a clear front-facing single-person half-body photo. If a fixed character identity is not required, you can skip uploading an image.

6.Use unified output settings at 1080P and keep each individual shot within 10 seconds.

7.After generating the video, check all dialogue carefully. If any words are missing or modified, immediately remove unnecessary negative descriptions and regenerate the video.

II. Two Key Basic Concepts

1. Negative Prompts (Optional)

Place them at the beginning of the entire prompt to help reduce issues such as facial distortion, incorrect lip movements, and visual flickering.

However, adding negative prompts will make the overall text longer, which may reduce AI’s priority in recognizing the script. Therefore, avoid using them whenever possible.

Unified Simplified Version:

Face distortion, mouth dislocation, picture flickering, blurry, deformed facial features, weird expression

2. Reference Portrait Image

Uploading a single front-facing portrait can lock the character’s appearance. Without using a reference image, facial features may change every time the video is generated, making it unsuitable for creating a series of short videos with the same character.

Portrait images with backlighting or facial obstructions are difficult for the system to recognize, which can also increase the chances of incorrect dialogue reading or missing words. Avoid using these types of images whenever possible before uploading materials.

Portrait Selection Criteria:

·Front-facing, looking straight at the camera

·Single person, half-body shot

·Even lighting

·No mask or sunglasses blocking the face

Avoid Using:

·Side-profile photos

·Group photos

·Long-distance shots where the face is too small

·Blurry images with backlighting

III. Standard Prompt Writing Method

Multilingual Speaking Sentence Format Explanation

The phrase “please say in English” shown in the examples is only used as a reference format for English. When creating videos in Spanish, French, or other languages, simply replace the language name in the middle section.

For example, “please say in Spanish” and “please say in French” can be directly applied using the same structure.

In addition, the prompt should follow a specific order. It is recommended to use the following structure:

Optional negative prompts, script-locking instruction, character visual description, target language speaking instruction, and the complete script at the end.

Changing this order may cause recognition failures.

Required Script-Locking Sentence for Gemini Omni

Read all text completely without adding, deleting or modifying any words, speak accurately in the designated language.

Practical Notes for Writing Prompts

1.Place the speaking instruction directly before the script. Do not put it at the end of the paragraph.

2.Control the dialogue length within a single shot. Long content should be divided into multiple shots.

3.Only use the official English name of the target language. Do not create abbreviations or unofficial terms.

4.If negative prompts must be used, keep them to one line only. When dialogue accuracy is affected, remove them first.

5.Set only one language instruction for each shot. Do not include bilingual speaking instructions in the same shot.

Reference Shot Templates

1. Single-Shot Template

Read all text completely without adding, deleting or modifying any words, speak accurately in the designated language.

A blonde woman in a beige coat stands in front of a coffee shop, with a gentle expression and a slow, soft tone, please say in English: "Good morning, what lovely weather today."

Add Negative Prompts Only When Visual Issues Are Severe

If facial distortion occurs frequently, place a simplified negative prompt at the very beginning.

The script-locking instruction, character description, and dialogue format after it should remain exactly the same as the example above.

2. Multi-Shot Continuous Writing Method

When connecting multiple scenes, use “Cut to next shot” to separate different shots.

For normal short videos, there is no need to add negative descriptions.

Example of Two Connected Shots:

Read all text completely without adding, deleting or modifying any words, speak accurately in the designated language.

Start with medium shot: A 28-year-old Caucasian woman stands on the lawn and speaks lightly and naturally, please say in English: "This place feels like a beautiful dream." Cut to next shot. Cut to close-up shot: She closes her eyes slightly and narrates in a gentle calm tone, please say in English: "This experience is absolutely unforgettable."

3. How to Create Bilingual Short Videos

Set different languages in separate shots. Do not use multiple languages within the same shot.

Bilingual content must be divided into separate shots. Do not mix two languages within the same section of text.

Full-Scene Example:

Read all text completely without adding, deleting or modifying any words, speak accurately in the designated language.

Wide shot: A Caucasian shop assistant stands in front of the store with an enthusiastic tone, please say in English: "Welcome to our store." Cut to next shot. Cut to medium close-up, the shop assistant waves to signal, please say in Spanish, standard pronunciation: "Tenemos muchos productos nuevos."

IV. How to Choose Between the Two Generation Models

The underlying recognition logic of the two models is different. You cannot directly copy prompts from one model and apply them to the other.

When switching models, remember to remove unnecessary visual descriptions.

V. Choosing the Right Character Movement Level

For shots containing dialogue, avoid describing large movements. Excessive text will occupy the space needed for script recognition and may also cause lip-sync errors.

VI. Complete Standardized Production Process

1.Split long scripts into shorter sections. If a single section contains more than 80 words, divide it into multiple shots.

2.Avoid using negative prompt text throughout the entire process whenever possible.

3.Arrange the entire prompt according to the fixed structure order.

4.Choose the appropriate model based on the required level of script accuracy.

5.If you need a consistent character appearance, upload a compliant single-person front-facing photo.

6.Use unified output settings at 1080P and keep the duration of each individual shot within 10 seconds.

7.Paste the complete prompt text and generate the video.

8.Checking order: First verify the completeness of the script, then check pronunciation and lip-sync accuracy.

9.If script errors or visual distortions occur, first remove negative descriptions and simplify unnecessary details before trying again.

VII. Solutions to Common Problems

1. AI Automatically Modifies or Misses Dialogue (Most Common Issue)

·First, split the shots into shorter sections, remove all negative prompts and unnecessary lighting descriptions.

·Switch to the Gemini model and add the script-locking instruction.

·Reduce the amount of character movement descriptions.

2. Character Lip Movements Do Not Match the Voice

·Switch to Seedance for generation.

·Replace the reference image with a clear front-facing portrait.

·Adjust movement intensity to small or medium levels. If visual issues are severe, temporarily add negative prompts.

3. Facial Distortion or Continuous Visual Flickering

Temporary solution: Add simplified negative prompts.

Long-term stable solution: Remove all unnecessary descriptions, cancel negative prompts, and simplify the overall prompt text.

VIII. Common Mistake-Avoidance Tips for Daily Creation

1.Use as few visual descriptions and negative prompt texts as possible to reduce the overall prompt length.

2.For multilingual short videos, set only one language for each shot to prevent AI recognition confusion and incorrect language switching.

3.Avoid extreme lighting descriptions such as harsh lighting or pure black backlighting, as they increase the AI’s recognition burden.

4.Split multi-person conversations into separate shots and assign short sentences to each shot.

5.When visual issues appear, prioritize adjusting the positive scene descriptions instead of relying on negative prompts for correction.

6.When the entire prompt becomes too long, remove negative prompts and unnecessary adjectives first.