What MTS files are and why you might need to convert them

MTS files are video recordings from camcorders and action cameras — particularly older Panasonic, Sony, and JVC models. MTS stands for MPEG Transport Stream, a format designed for how those cameras store video internally. The problem is that most video editing software, phones, and streaming platforms expect MP4 files instead.

You'll run into this if you've pulled footage from a camcorder and want to edit it in software like DaVinci Resolve, Adobe Premiere, or even Windows Photos. Your computer might not recognize the file, or the editing program might refuse to import it. Converting to MP4 solves this because MP4 is a container format that works almost everywhere — it's what YouTube accepts, what your phone plays natively, and what most editing tools open without complaint.

The conversion itself doesn't reduce quality if you use the right settings. You're not re-encoding the video data into something worse; you're moving the same video stream into a different wrapper that more programs understand.

Key Takeaways

  • MTS files come from camcorders and need conversion because most editing software and devices expect MP4 instead.
  • Free desktop tools like HandBrake and FFmpeg can convert MTS to MP4 without quality loss if you keep the same codec settings.
  • Online converters exist but require uploading your video file to someone else's server, which poses privacy risks for personal footage.
  • The conversion process takes longer than the video itself — a 30-minute MTS file might take 45 minutes to an hour to convert, depending on your computer.
  • After conversion, verify the MP4 file plays and has audio before deleting the original MTS file.

Using HandBrake for straightforward conversion

HandBrake is free, runs on Windows, Mac, and Linux, and handles MTS files without special configuration. Download it from handbrake.fr, install it, and open the program.

Click "Open Source" and select your MTS file. HandBrake will scan it and show you the video properties — resolution, frame rate, and audio tracks. In the "Summary" tab on the right, change the format dropdown from "Matroska" to "MP4". Leave the video codec as H.264 (or H.265 if your original is H.265 — HandBrake will show you which one it detected). This keeps the video quality identical to the original.

Click "Start Encode" at the top right. HandBrake will process the file in the background. A progress bar shows how far along it is. Once finished, you'll have an MP4 file in the same folder as your original MTS file. The new file will be roughly the same size as the original because you're not changing the video quality, only the container.

Using FFmpeg from the command line

FFmpeg is a command-line tool that's faster than HandBrake for simple conversions and gives you more control. It's free and available for Windows, Mac, and Linux. Download it from ffmpeg.org and follow the installation instructions for your operating system.

Open your terminal or command prompt and navigate to the folder containing your MTS file. Type this command:

ffmpeg -i input.mts -c:v copy -c:a copy output.mp4

Replace "input.mts" with your actual filename and "output.mp4" with what you want to call the result. The "-c:v copy" and "-c:a copy" flags tell FFmpeg to copy the video and audio without re-encoding, which is fast and preserves quality. FFmpeg will show you progress in real time. When it finishes, you have your MP4 file ready to use.

If you want to re-encode for smaller file size or compatibility with older devices, replace those flags with "-c:v libx264 -crf 23 -c:a aac -b:a 128k". The "-crf 23" controls quality (lower numbers mean higher quality; 23 is a good balance). This takes longer but gives you a smaller file.

Online converters and their privacy trade-offs

Websites like CloudConvert, Online-Convert, and Zamzar let you upload an MTS file and download an MP4 without installing software. They're convenient if you only have one or two files to convert and your internet connection is fast enough to upload the video.

The trade-off is that your video file leaves your computer and sits on someone else's server during conversion. If your footage contains personal moments, family videos, or anything you wouldn't want stored elsewhere, this route carries real risk. Even if the service deletes files after conversion, there's a window where your video exists on their infrastructure, potentially backed up or accessible to their staff.

Some online converters are free but show ads or limit file size (often to 500 MB or 1 GB). Paid versions remove these limits. If you do use an online converter, check their privacy policy first — specifically how long they keep files and whether they use your uploads for training AI models.

Batch converting multiple MTS files

If you have dozens of MTS files from a trip or event, converting one at a time is tedious. HandBrake has a "Batch Scan" feature: click "Open Source" and select a folder instead of a single file. HandBrake will add every video in that folder to a queue. Set your MP4 output settings once, then click "Start Encode" to process them all in sequence overnight or while you work on something else.

With FFmpeg, you can write a script to loop through all MTS files in a folder. On Windows, create a text file in your video folder with this content:

for %%f in (*.mts) do ffmpeg -i "%%f" -c:v copy -c:a copy "%%~nf.mp4"

Save it as "convert.bat", then double-click it. FFmpeg will convert every MTS file in that folder to MP4. On Mac or Linux, the syntax is slightly different — use a bash script instead — but the principle is the same.

Checking your converted file before deleting the original

After conversion finishes, open the new MP4 file in a media player (Windows Media Player, VLC, QuickTime, or your phone) and play through at least the first minute and the last minute. Listen for audio — sometimes conversion fails silently on the audio track, leaving you with video and no sound. Check that the video plays smoothly without stuttering or corruption.

If the MP4 plays correctly, you can delete the original MTS file. If something went wrong, you still have the source to try again with different settings. Don't delete the MTS until you've confirmed the MP4 works, especially if you're converting footage you can't re-shoot.

Troubleshooting common conversion problems

If HandBrake or FFmpeg won't open your MTS file, the file might be corrupted or your tool might be outdated. Try updating to the latest version of your conversion software first. If that doesn't work, try the other tool — sometimes one handles a particular camera's MTS variant better than the other.

If the converted MP4 has no audio, the original MTS file might have audio in a format your converter doesn't recognize, or the audio track might be damaged. In HandBrake, check the "Audio" tab to see if it detected multiple audio tracks. Select the one you want to keep. In FFmpeg, add "-c:a aac" to re-encode the audio into a format MP4 handles reliably, even if it takes longer.

If the file size is much larger than expected after conversion, you may have accidentally re-encoded the video. Check that you used the "-c:v copy" flag in FFmpeg or that HandBrake's codec was set to "Copy" rather than "H.264". Re-encoding creates a new video stream and takes much longer.

Frequently Asked Questions

Will converting MTS to MP4 make the video quality worse?

No, if you use the copy settings in HandBrake or FFmpeg. You're moving the video data into a new container, not re-encoding it. The video quality stays identical. Only re-encode if you want a smaller file size, and then quality will depend on the settings you choose.

Can I convert MTS to MP4 on my phone?

Not easily. Most phone apps that claim to convert video actually just change the file extension without truly converting, which doesn't solve the compatibility problem. Desktop tools like HandBrake or FFmpeg are more reliable. If you must use your phone, upload to an online converter, but understand the privacy implications of sending personal video to an external server.

How long does conversion take?

If you're copying the video without re-encoding, it's usually faster than real-time — a 30-minute video might take 10 to 15 minutes. If you're re-encoding for quality or file size, expect it to take longer than the video itself, sometimes two to three times as long, depending on your computer's processor.

Do I need to keep the original MTS file after converting?

Not unless you want a backup. Once you've verified the MP4 plays correctly with audio and video, the MTS file is redundant. Delete it to free up storage space. If the conversion failed or the MP4 is corrupted, you'd need the MTS to try again, so wait until you're certain the MP4 is good before removing the original.

What if my camera recorded in a different format, like MOV or AVI?

The same tools work for those formats too. HandBrake and FFmpeg handle dozens of video formats. Just open the file the same way — they'll detect the format automatically and convert to MP4 using the same process.