Free Online Video Converter & Compressor

1. Format Conversion

• Supported formats: MP4, WebM, MOV, AVI, MKV, WMV, FLV
• Select "Convert" operation and choose the target format (e.g., MOV to MP4)
• Click the "Start Processing" button, and the system will complete the conversion locally in your browser
• Processing progress will be displayed during conversion, and you can download the video in the new format after completion

2. Video Compression

• Select "Compress" operation and choose compression mode
• Lossless compression: Maintains original quality using fast preset and low CRF value (CRF 18) to optimize file size
• Lossy compression: Balances quality and file size using medium preset and higher CRF value (CRF 28), with bitrate limits (video 1Mbps, audio 128kbps)
• Compression may take a considerable amount of time, please be patient

3. Batch Processing

• You can upload multiple video files simultaneously
• All files will be processed in queue order to avoid browser performance issues from processing multiple large files simultaneously
• Each file can be downloaded individually after processing is complete

4. File Size Limits & Notes

• Single file limit: Maximum 150MB per video file
• Total file size limit: Maximum 1000MB total file size per session
• File count limit: Maximum 15 files can be processed simultaneously
• Large file processing warnings:
• Video processing is more time-consuming than image processing; we recommend keeping individual files under 50MB for the best experience
• Video files over 100MB may cause processing timeout (up to 45 minutes) or browser memory issues
• 20-50MB videos may take 20-30 minutes, while 50-100MB videos may take 30-45 minutes
• If processing fails due to timeout from large files, consider compressing the video with another tool first
• Keep the browser tab open when processing large files to avoid interruption from switching tabs
• We recommend processing in a stable network environment to avoid failures due to network issues

Video Processing Engine

1. Uses FFmpeg.wasm (WebAssembly version of FFmpeg) to process videos in the browser:
2. FFmpeg.wasm is a WebAssembly port of FFmpeg, providing complete video encoding and decoding capabilities
3. All processing is completed in a virtual file system within browser memory
4. Uses iframe isolation environment to ensure stable module loading and execution
5. Supports multi-threaded processing (requires SharedArrayBuffer support)

Format Conversion Process

1. Read video file as ArrayBuffer and write to FFmpeg virtual file system
2. Use FFmpeg commands for transcoding: -c:v libx264 (video encoder), -c:a aac (audio encoder)
3. Set encoding parameters: preset controls encoding speed, CRF value controls quality (range 18-28)
4. Read processed video data from virtual file system and convert to Blob
5. Clean up temporary files and release memory

Compression Principle

1. Lossless compression: Uses CRF 18 (high quality) and fast preset to optimize encoding efficiency while maintaining visual quality
2. Lossy compression: Uses CRF 28 (lower quality) and medium preset, with video bitrate (1Mbps) and audio bitrate (128kbps) limits to significantly reduce file size
3. All processing is completed locally in the browser without relying on server resources