Video Compressor

Video compression reduces file size by removing redundant information. Spatial compression (within a frame) replaces repetitive pixel patterns — a blue sky in a frame does not need every pixel stored individually. Temporal compression (between frames) stores only the differences between consecutive frames — in a talking-head video, the background is static so only the speaker's face area changes frame-to-frame. The H.264 codec (the most widely supported) achieves compression ratios of 50-100x compared to raw video. A 1-minute 1080p raw video is approximately 10 GB; H.264 compresses it to 100-200 MB at good quality. H.265/HEVC achieves 25-50% better compression than H.264 at the same quality but with less device compatibility. VP9 (used by YouTube) and AV1 (the newest open-source codec) offer similar improvements. This compressor uses ffmpeg.wasm in your browser to re-encode video with adjustable quality settings. The CRF (Constant Rate Factor) scale runs from 0 (lossless) to 51 (worst quality): 18 is visually lossless, 23 is the default (good quality), and 28 is acceptable for web sharing. Your video files never leave your device during compression.

The right compression settings depend on your use case. For archival storage, CRF 18-20 preserves nearly all visual detail while reducing file size by 30-50% from the original. For sharing via email (most providers limit attachments to 25 MB), aggressive compression at CRF 28-32 with reduced resolution (720p instead of 1080p) can bring a 5-minute clip under the limit. Social media platforms re-compress your uploads regardless, so uploading at medium quality (CRF 23, 1080p) is sufficient — YouTube, Instagram, and TikTok all apply their own encoding. Resolution reduction has the biggest impact on file size: 1080p to 720p typically halves the file size. Reducing framerate from 60 to 30 FPS saves another 30-40% with minimal perceptual difference for non-gaming content. Audio quality is often overlooked: video files with AAC audio at 192 kbps sound great; reducing to 128 kbps saves a few percent with barely noticeable difference. Bitrate calculators help estimate output size: target_size_MB = (bitrate_kbps x duration_seconds) / 8000. For a 3-minute video at 2500 kbps video + 128 kbps audio: (2628 x 180) / 8000 = approximately 59 MB.