Faster conversions and smaller files
In-browser conversion is convenient and private, but your CPU and RAM do all the work. A few habits keep things snappy and files small.
Video
- Prefer MP4 — H.264 is efficient and widely supported.
- Avoid huge masters — 4K hour-long files will be slow; trim first or use a desktop encoder for those.
- GIF only for short clips — ConvertFlow limits GIF length and resolution so the result stays usable.
- The engine downloads once (~25 MB). After that, conversions reuse the loaded core.
Images
- WebP or AVIF often beat JPG at the same visual quality with smaller size.
- Use the quality slider (JPG/WebP) — 80–90% is usually enough.
- Resize to the target platform size instead of uploading a 6000 px original.
- Black fill (default) looks clean when letterboxing vertical content for landscape slots.
If progress seems stuck
First load of the conversion engine can take 10–40 seconds depending on connection. A progress bar and status text show activity. If it fails, check that the site is served over HTTPS and that cross-origin isolation headers are present (ConvertFlow ships with the required _headers for common hosts).