> ## Documentation Index > Fetch the complete documentation index at: https://docs.optima.onl/llms.txt > Use this file to discover all available pages before exploring further. # Audio & Video Tools > AI voiceover, speech recognition, video compression and editing # Audio & Video Tools AI text-to-speech, speech recognition, plus video compression, trimming, voiceover, and more. ## AI Text-to-Speech Have AI read text aloud in a natural voice — perfect for product video voiceovers and audio introductions. Over 50 voices available, with automatic language detection for Chinese, English, Japanese, Korean, and more. ### Basic Voiceover ``` Read this aloud: "Welcome to our store, featuring the latest wireless headphones" ``` ``` Read this in Chinese: "欢迎来到我们的店铺" ``` ### Choose a Voice ``` Read this introduction using the Cherry voice ``` ``` Generate this English narration with the Ethan voice ``` Not sure which voice to pick? Just say "add a voiceover" and AI will automatically choose an appropriate voice based on the content. ### E-commerce Applications ``` Add a Chinese voiceover to this product video ``` ``` Generate a 30-second product introduction audio ``` ``` Read this product description in Japanese ``` ### Supported Languages | Language | Notes | | -------------------- | -------------------------------------- | | Chinese | Auto-detected Mandarin | | English | Natural American/British pronunciation | | Japanese | Natural Japanese pronunciation | | Korean | Natural Korean pronunciation | | French, German, etc. | Multi-language support | ## AI Speech Recognition Convert speech in audio or video files to text. Supports multiple audio formats. ### Basic Recognition ``` Transcribe this recording [Upload audio file] ``` ``` What does this video say [Upload video file] ``` ### Specify Language ``` Transcribe this Chinese audio [Upload audio] ``` ``` Convert this English recording to text [Upload audio] ``` ### E-commerce Applications ``` Transcribe the competitor's product video — I want to see how they pitch it ``` ``` Convert customer voice feedback to text ``` ### Supported Formats | Format | Notes | | ---------- | ------------------------------- | | MP3 | Most common audio format | | WAV | Lossless audio | | M4A | Default iPhone recording format | | OGG / WebM | Web audio formats | Audio file size limit is 25MB. For longer recordings, trim first before transcribing. *** ## Video Compression ### Compress Video ``` Compress this video [Upload video] ``` ``` Compress video to under 10MB ``` ### Compression Guidelines * **Social media**: 1080p, 5-10MB * **Product display**: 720p, 2-5MB * **Thumbnail preview**: 480p, under 2MB ## Video Trimming ### Extract Segment ``` Extract video from 0:10 to 0:30 ``` ``` Trim first 15 seconds of video ``` ### Remove Intro/Outro ``` Remove last 5 seconds of video ``` ## Video Compositing ### Add Background Music ``` Add background music to video [Upload video] [Upload audio] ``` ### Add Voiceover ``` Add this voiceover to the video ``` ### Replace Audio ``` Replace the video's original audio ``` When adding audio, if audio is shorter than video it will loop, if longer it will be trimmed. ## Video Concatenation ### Merge Multiple Videos ``` Concatenate these videos [Upload video1] [Upload video2] [Upload video3] ``` ### Set Order ``` Concatenate in order: Video A, Video B, Video C ``` ## Format Conversion ### Convert Format ``` Convert video to MP4 format ``` ### Common Formats | Format | Use Case | | ------ | ------------------------------------ | | MP4 | Universal format, best compatibility | | WebM | Web playback | | MOV | High-quality editing | ## Generate Thumbnail ### Extract Thumbnail ``` Extract a thumbnail from the video ``` ``` Use frame at 5 seconds as thumbnail ``` ### Auto-Select ``` Automatically select best thumbnail ``` AI analyzes the video to select the clearest, most attractive frame as thumbnail. ## Video Adjustments ### Resize ``` Crop video to 1:1 square ``` ``` Resize video to 9:16 vertical ``` ### Quality Enhancement ``` Enhance video clarity ``` ## Batch Processing ### Batch Compress ``` Batch compress these videos ``` ### Batch Convert ``` Convert all videos to MP4 ``` Batch processing may take longer. You'll be notified when complete. ## E-commerce Video Tips Upload platforms usually have size limits. Keep under 50MB. First 3 seconds are crucial. Grab attention immediately. Many users watch with sound off. Subtitles improve message delivery. Different platforms have different size requirements. May need multiple versions.