Convert M4V to MP4 on Mac (and What Is M4V?)

M4V is Apple’s variant of the MP4 container. Inside is usually H.264 video and AAC audio, the same streams an MP4 holds. Apple used the extension for iTunes movies, TV shows and some exported video. The difference that matters is copy protection: purchased and rented iTunes videos carry Apple DRM, while videos you exported or ripped yourself usually do not.

Often, yes. We made an H.264/AAC M4V test clip, copied it to a file ending in .mp4, and ffprobe reported the same container family and the same codecs for both. Click the file in Finder, press Return, and change the extension.

If the renamed file plays in QuickTime Player and in the app you are sending it to, you are done. Nothing was re-encoded, so nothing was lost. If it will not play, it is probably DRM-protected (see below).

Copy the streams into a new MP4 instead of re-encoding them. With ffmpeg (brew install ffmpeg):

ffmpeg -i movie.m4v -c copy movie.mp4

On our test clip this produced 88,794 bytes from an 88,782-byte original, a few bytes of container overhead and no quality change. It finishes in about a second even for long videos, because nothing is re-encoded. For a batch, wrap it in a loop:

for f in *.m4v; do ffmpeg -i "$f" -c copy "${f%.m4v}.mp4"; done

Movies and shows bought or rented from iTunes or the Apple TV app are protected with Apple’s DRM. The protected video stream cannot be decoded outside Apple’s own players, so renaming, ffmpeg, VLC and Smol all fail on it or produce a file that will not play. We do not recommend DRM-removal tools: they are legally murky in many countries and often unreliable.

Your options are to watch the title in the TV app or on Apple devices, or to get an unprotected copy from the source. Home videos and your own exports are not affected.

Yes, for unprotected files. Drop M4V files into Smol, choose Convert, set the output to MP4 (or MOV, WebM, MKV) and run. We tested our 88,782-byte H.264 M4V clip and Smol wrote a working MP4 in under a second. It re-encodes rather than copying, and on this tiny clip the output was bigger (124,908 bytes, 40.7% larger). That is the cost of re-encoding a video that was already small.

So use Smol on M4V when you also want a different size, a different codec, or a resolution drop. When you only need the container changed, the rename or the copy command is better.

For one M4V, renaming or the copy command is faster and keeps every pixel. QuickTime Player also opens unprotected M4V files directly, so you may not need to convert at all. Smol is the wrong tool for protected iTunes videos too, since it cannot touch them.

Smol earns its $29 when the pile is mixed and big: M4V, MOV, MKV and WebM files you want as smaller MP4s in one pass, from a Finder right-click, with nothing leaving your Mac. Details are on the buy page. To shrink the results, see the best video compressor for Mac.

Other formats work the same way: MOV to MP4, MKV to MP4, and the best file converters for Mac.