Convert a video to MP4 in your browser
TubePull Convert to MP4 turns an MKV, MOV, TS, FLV, AVI, WebM, WMV or 3GP file into an MP4. The conversion happens on your computer or phone, inside this browser tab. Your video never travels to TubePull or anywhere else, and you don't need an account. There are no settings to get right. The tool looks at every track in the file. Each one that MP4 can carry as it is gets copied without re-encoding. Only the tracks that can't be copied are re-encoded. When the video is H.264 or HEVC and the audio is AAC or MP3, which covers most phone videos and screen recordings, nothing is re-encoded and the picture and sound stay exactly as they were.
What happens to each track
| Track in your file | In the MP4 | Quality |
|---|---|---|
| H.264 video | Copied without re-encoding | Unchanged |
| HEVC (H.265) video | Copied without re-encoding and tagged hvc1, the form Apple players expect | Unchanged |
| VP8, VP9, MPEG-4 Part 2 (Xvid, DivX), WMV and other video | Re-encoded to H.264 (8-bit, 4:2:0) at a high-quality setting, with the same frame size and frame rate | A small loss from one new encode |
| AAC or MP3 audio | Copied without re-encoding | Unchanged |
| Opus, Vorbis, FLAC, WMA, AC-3 and other audio | Re-encoded to AAC at 192 kbps with the same number of channels | A small loss from one new encode |
| AV1 video | Can't be converted (see Limits below) | No MP4 is made |
When a re-encoded video has an odd width or height, that side is rounded down by one pixel, because 4:2:0 H.264 needs even sizes. Each frame keeps its original timing, so a phone video with a variable frame rate stays in sync. Re-encoded audio keeps its sample rate up to 48 kHz; higher rates become 48 kHz. After the conversion, a short list tells you what happened to each track: copied or re-encoded, and which tracks were left out. When everything was copied, it says that no quality was lost.
Popular conversions
- MKV to MP4. Recordings from OBS and other screen recorders are often MKV files with H.264 and AAC, so they are copied in full. If you recorded several audio tracks, such as game sound and microphone, every one of them is kept.
- MOV to MP4. Most iPhone and QuickTime videos hold H.264 or HEVC with AAC sound, so they are copied as well. An HEVC video stays HEVC.
- WebM to MP4. WebM uses VP8 or VP9 video with Opus or Vorbis sound, which many phones, editors and players don't accept in an MP4, so both are re-encoded to H.264 and AAC.
- AVI to MP4. Older AVI files usually hold Xvid or DivX video, which is re-encoded. Their MP3 sound is copied.
- TS to MP4. Recordings from TV tuners, DVRs and live-stream captures are MPEG-TS files. H.264 with AAC is copied; older MPEG-2 recordings are re-encoded.
- FLV to MP4. Old Flash videos often hold H.264 and AAC, which are copied into a file that modern players open.
- WMV to MP4. Windows Media video and audio always need re-encoding.
- 3GP to MP4. Videos from older phones are copied when they hold H.264 and AAC, and re-encoded otherwise.
Does converting to MP4 lose quality?
Only when a track has to be re-encoded. A copied track keeps the same compressed frames and audio packets, so it is the same video in a different container. The file size usually stays close to the original. A re-encode decodes the track and compresses it again, which always loses a little detail. The tool uses a setting where the loss is hard to see, but it can't make a video better than its source, and the new file can be larger or smaller than the old one. When the aim is a smaller file, the Video Compressor lets you pick a quality level or a size in MB. Renaming a file from .mkv or .mov to .mp4 doesn't convert it. The extension is only a label: the data inside is still arranged the old way, and many players refuse it. This tool reads the format from the file's content, so a file with the wrong extension is still handled correctly.
What the MP4 keeps and what it leaves out
- Kept: the first video track and every audio track, in their original order. The MP4 has the same length as the original, to within a tenth of a second.
- Tags: titles and other tags that MP4 can store are kept, and so is the recording date. The conversion doesn't add today's date. Location and camera details in an iPhone video can come along too, so keep that in mind before you share a private one. The Video Metadata Remover can take them out of the converted MP4.
- Left out: subtitle tracks, data tracks (such as timecode), attached fonts and pictures, chapters and cover art. The result list names each one with its codec. When the file was read in the page rather than by the compatibility engine described below, the list can't see subtitle and data tracks, so it says in one sentence that any such tracks were left out. Keep the original if you need them.
- Fast start: the MP4's index is written before the video data, so a player or website can start playing it before the whole file has downloaded.
Where the conversion happens
The video is opened from your device and converted in this tab. The page makes no network request that contains your video, its name or its details; it only loads the tool's own program files from TubePull. When every track can be copied and your browser can read the file, as with most MKV, MOV, TS and 3GP files, the tracks are copied straight into the MP4 in the page by Mediabunny, an open-source media library, with no large download. When a track needs re-encoding, or the file is FLV, AVI or WMV, the tool uses its compatibility engine instead: FFmpeg compiled to WebAssembly (ffmpeg.wasm). That engine is about 32 MB. It downloads the first time a job needs it and then stays in your browser's cache. Exact versions, licenses and source code links are on the licenses page.
Limits
- MP4 files aren't accepted, since they are already MP4. To cut one, use the Video Trimmer.
- AV1 video can't be converted. This tool would have to re-encode it, and the compatibility engine can't decode AV1, so you see a message that the browser can't process the codec. Another browser won't help with this tool.
- HEVC is copied, not changed to H.264. It plays on recent Apple devices and most recent phones and TVs, but some older computers and players can't decode HEVC.
- On the compatibility engine, a job is refused when its output is estimated at more than about 1.5 GB. For this tool the estimate is the size of your file, so a file over 1.5 GB converts only when every track can be copied in the browser.
- Your device's memory sets the practical size limit. On a phone, files over 500 MB bring up a warning, but you can still start the conversion.
- One file at a time. Videos protected with DRM can't be converted.
Starting from a link
This tool converts files you already have. To save a YouTube video as MP4 from its link, use the YouTube to MP4 downloader. For other sites, paste the link into the TubePull downloader. Once you have the MP4, you can cut it with the Video Trimmer, take its sound with Video to MP3, or browse the other free video tools.