F4V to MP4 Converter
Convert F4V files, the Adobe Flash Video format, to MP4 that plays on any phone, computer or TV. Most F4V files already contain MP4-style video and sound, so the conversion is often instant and lossless; when it isn't, you get full control over quality, bitrate, frame rate, resolution and audio.
Also: MKV to MP4 converter · AVI to MP4 converter · MOV to MP4 converter · WebM to MP4 converter · FLV to MP4 converter · TS to MP4 converter · WMV to MP4 converter · MPEG to MP4 converter · 3GP to MP4 converter · M4V to MP4 converter · MOD to MP4 converter · VOB to MP4 converter · MTS to MP4 converter · OGV to MP4 converter · RM/RMVB to MP4 converter · MXF to MP4 converter · DV to MP4 converter · SWF to MP4 converter · MP4 compressor · Video to MP3 extractor · MP4 to GIF converter · Video format converter
Click to choose a video, or drag and drop
Choose an F4V video file — MKV, AVI, MOV, FLV and most other formats are accepted too. Stays on your device.
Your video is converted entirely in your browser and is never uploaded. The converter engine (ffmpeg, ~32 MB) is downloaded once and cached by your browser.
Frequently asked questions
What is an F4V file?
F4V is Adobe's newer Flash Video format, used by Flash Player and Adobe Media Server from 2007 onwards for recordings, downloads and archived streams. It is built on the same container design as MP4 and normally holds H.264 video with AAC audio. Few phones, TVs or editors recognise the .f4v extension, which is why converting to MP4 helps.
Why was my F4V converted in seconds?
Because the video and audio inside an F4V file are usually already in MP4-compatible codecs (H.264 and AAC), the tool can copy them into a new MP4 without re-encoding. That is almost instant and keeps the exact original quality. You can still choose to re-encode if you want a smaller file or a different resolution.
What is the difference between F4V and FLV?
FLV is the older Flash Video container, often with Sorenson Spark or VP6 video. F4V is the newer one and carries H.264 and AAC like MP4. This page is for F4V; for older .flv files use the FLV to MP4 converter, which handles those older codecs.
Can it convert a file that was recorded from a live stream?
Yes. Recordings saved from Flash Media Server or other live-streaming software are ordinary F4V files and convert the same way. If a recording was cut off partway, the tool converts as much as it can read.
Is my video uploaded anywhere?
No. The conversion runs entirely in your browser using ffmpeg compiled to WebAssembly. Your video never leaves your device. Only the converter engine itself (about 32 MB) is downloaded, once, and cached by your browser.
What is Fast remux and when should I use it?
A F4V file is just a container. If the video inside is H.264 (or another format MP4 supports) and the audio is AAC, MP3 or AC-3, those streams can be moved into an MP4 container as they are. That takes seconds and loses no quality at all. The tool checks your file and picks this automatically when it is possible.
What do CRF and bitrate mean?
CRF (constant quality) lets the encoder spend as many bits as each scene needs: lower numbers mean better quality and bigger files, around 18 looks near-lossless, 23 is the default and 28 is noticeably smaller. A target bitrate instead aims for a fixed number of kilobits per second, which gives a predictable file size but variable quality.
Why is re-encoding slow, and is there a size limit?
Re-encoding runs on a single CPU thread inside the browser (H.264 only), so it is usually near real-time speed or slower for HD. The finished MP4 also has to fit in browser memory, which in practice limits output to roughly 1 to 2 GB. For a long movie, use Fast remux, trim it, or copy the generated command and run it with ffmpeg on your own computer.
What happens to subtitles?
MP4 supports text subtitles only. SRT, ASS/SSA and WebVTT tracks are converted to the MP4 text format, and you can also save a track as a separate .srt file. Picture-based subtitles from Blu-ray or DVD (PGS, VobSub) cannot be converted.