Phone videos are recorded at high bitrates so they look good whatever happens later. For sharing, most of that data is unnecessary. Compressing re-encodes the video with H.264, the most widely supported video codec, at a bitrate that fits the content.
How is quality controlled?
With a value called CRF, short for constant rate factor. Instead of a fixed bitrate, CRF asks the encoder for a constant visual quality and lets the file size follow. Lower numbers mean better quality and bigger files; higher numbers mean smaller files and more visible loss. Here you can choose from 18 to 40.
The default is 28, a good setting for sharing and web use. Around 23 looks very close to the source, and 18 is close to visually lossless. Above 30 or so, you start to see blockiness in dark areas and during fast motion. As a rule of thumb, raising CRF by 6 roughly halves the file size.
The output is always an MP4 with H.264 video and AAC audio at 128 kbps, set up to start playing before it has fully downloaded.
How much smaller will it get?
That depends on the source. A 4K phone video with lots of detail and motion shrinks a lot at CRF 28. A screen recording or a video that was already compressed for the web may barely change, and occasionally comes out larger; in that case keep the original.
For 4K footage, the max height option saves far more than CRF alone. Set it to 1080 or 720 and taller videos are scaled down, keeping their shape; smaller ones are left as they are.
Is my file stored?
Video compression runs on our server. The file is uploaded over an encrypted connection, processed in Germany, and deleted with the result automatically within two hours.
What are the limits and how long does it take?
Video is a heavy tool: the free tier includes 3 videos per day without an account and 5 with a free account, up to 50 MB each. Pro accepts files up to 500 MB with no daily cap, and single large jobs can be paid with a credit instead. Encoding time grows with the length and resolution of the clip, so a short phone video is done quickly and a long 4K recording takes a while. The pipeline builder can compress a whole folder of clips overnight, with the same CRF for all of them.
How to compress a video
- Drop your video onto the drop zone. MP4, MOV, MKV, WebM, AVI, WMV, 3GP and other common formats work.
- Set the CRF, or keep 28, and pick a max height if you want a smaller resolution.
- Click Compress and wait for the encode to finish.
- Download the compressed video.
FAQ
What CRF should I use for WhatsApp or email?
28 is a good start. If the file is still too large, set max height to 720 as well.
Will the resolution change?
Only if you set a max height. With keep, the width and height stay as they are.
Why is my compressed video bigger than the original?
The source was already efficiently compressed, or you chose a lower CRF than its equivalent quality. Try a higher CRF, or keep the original.
Does it keep subtitles and multiple audio tracks?
The main video and audio tracks are kept. Extra subtitle and audio tracks may be dropped.