How do I compress video ffmpeg?
Re-encodes with a quality target and web-friendly flags, which is what makes a file both smaller and playable everywhere.
Compress a video for the web
Re-encodes with a quality target and web-friendly flags, which is what makes a file both smaller and playable everywhere.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -c:v libx264 -crf 26 -preset medium -c:a aac -b:a 128k -movflags +faststart -t 5 out.mp4- Encode
- 896 ms
- Output
- 419.1 KB
- Cost
- $0.0022
- Result
- 1280x720
job_5455f4f702864327
The part everyone gets wrong
-movflags +faststart is the difference between a video that streams and one that must fully download first. It costs a second pass over the file and nothing else. Every MP4 destined for a browser should have it, and most compression guides never mention it.
What the common version does
Without +faststart the moov atom sits at the end of the file, so a browser must download the whole thing before playback starts.
ffmpeg -i https://cdn.rendobar.com/assets/examples/sample.mp4 -c:v libx264 -crf 26 -preset medium -c:a aac -b:a 128k -t 5 out.mp4It succeeds, and that is the problem
It did not error. It produced 419.1 KB against the correct command's 419.1 KB, a 1.0x smaller file. A pipeline would accept this silently.
job_3b20cb2ab35541a0
Frequently asked questions
What goes wrong most often?
-movflags +faststart is the difference between a video that streams and one that must fully download first. It costs a second pass over the file and nothing else. Every MP4 destined for a browser should have it, and most compression guides never mention it.
What happens if I get it wrong?
We ran the naive version too. It did not error. It produced 419.1 KB against the correct command's 419.1 KB, a 1.0x smaller file. A pipeline would accept this silently.
Do I need FFmpeg installed?
Not with Rendobar. The command on this page ran through the API against a URL, with no local FFmpeg and no server. The job id below it is the job that produced these numbers.
More recipes, all measured
Convert MP4 to GIF with FFmpeg Turns a video into an animated GIF using a generated palette, which is the difference between a usable GIF and a muddy one. Extract audio from video with FFmpeg Pulls the audio track out of a video, copying it without re-encoding when the format allows. Trim a video without re-encoding Cuts a section out of a video by copying streams, which is effectively instant and lossless. Remove audio from a video Strips the audio track and copies the video untouched, so there is no quality loss and almost no work.
Run this without installing FFmpeg
This exact command ran through the API against a URL.