Browser FFmpeg recipe
Convert MKV to MP4 Online with FFmpeg
Move compatible video into MP4 and encode audio to AAC when needed.
Command
Run this FFmpeg command
ffmpeg -i input.mkv -c:v copy -c:a aac -b:a 128k output.mp4When to use it
- container conversion
- faster remuxing
- MP4 compatibility
How it works
- Upload the MKV file.
- Run the command to copy video and encode audio.
- Download the MP4 output.
Option reference
| Option | What it does |
|---|---|
-c:v copy | Copies the video stream without re-encoding. |
-c:a aac | Encodes audio into an MP4-friendly codec. |
-b:a 128k | Sets a compact audio bitrate. |
Practical notes
- If MP4 rejects the video stream, use the generic Video to MP4 recipe instead.
- Copying video is faster and preserves video quality.
FAQ
Why can MKV to MP4 fail?
MP4 does not support every stream type that MKV can contain. Re-encoding fixes more cases.
Does this reduce video quality?
The video stream is copied, so video quality stays the same when the stream is compatible.