Convert M4V to MP4
M4V is Apple's version of MP4 - same file format under the hood, just with a slightly different name and file extension. iTunes purchases, Apple TV downloads, and iMovie exports typically save as .m4v. On Apple devices it plays perfectly; on Windows or Android or in an upload pipeline that only recognises .mp4, it sometimes gets rejected on the extension alone. Wave changes the file's label to .mp4 without touching the picture or sound at all - the conversion takes seconds and the output file is essentially identical to the input.
What actually changes
M4V is genuinely just MP4 with a different file-type box. Apple used the extension for iTunes video downloads, iOS device recordings, and some purchased content (which additionally carried FairPlay DRM). For non-DRM M4V files, the conversion is a trivial container header rewrite - every byte of video and audio survives untouched.
FairPlay-protected M4V (iTunes purchases from before 2009 for TV shows, or older iTunes rentals) cannot be decrypted outside Apple's ecosystem. Wave detects protected files during inspect and stops with a specific error message.
Apple introduced the .m4v extension in 2005 with the fifth-generation iPod (the first iPod with video), primarily as a way for iTunes to identify files that belonged to its media library. Structurally the file is a plain MP4 - same ftyp brand family, same box hierarchy, same codec choices (H.264 or HEVC video, AAC audio). The only meaningful differences are that some M4Vs carry an itunmovi atom with iTunes-specific metadata, and some carry FairPlay DRM. Neither prevents a plain MP4 rewrite for unprotected files.
On iOS, .m4v and .mp4 play through the same code path. On Android, WhatsApp, and various video-editor imports, the extension itself sometimes matters - some tools filter their file pickers to .mp4 only. Wave's rewrite gives you a file that satisfies those filters without changing a single byte of the compressed video or audio.
Three steps.
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Step 1
Drop the M4V onto the card.
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Step 2
Wave shows Fast copy - one of the fastest conversions in the tool.
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Step 3
Convert and save the MP4.
Answers, specifically.
Is M4V really different from MP4?
Structurally, no. Apple gave it a different extension so their apps could distinguish iTunes-associated files. Under the hood the container is MP4.
Why won't my Android device play M4V?
Some Android video players match on extension rather than content-type and reject anything that isn't .mp4. Renaming works most of the time, but a proper container rewrite (what Wave does) is more reliable.
What about iTunes-purchased shows?
Those carry FairPlay DRM. Wave can't decrypt them and won't try - no browser-side tool can. You'd need to re-download in an unprotected format.
Will my chapter markers carry over?
Yes. Chapter atoms are part of the MP4 container spec and copy through unchanged.
Does converting break subtitles?
Embedded MP4 subtitle tracks copy through. External .srt files aren't muxed by the current build.
iTunes movie extras and cover art - do those survive?
iTunes' cover art atoms (covr) and standard iTunes metadata (title, year, cast) copy through with the container. iTunes' "movie extras" tracks (deleted scenes, commentary as separate tracks) are typically preserved as auxiliary MP4 tracks; whether your target player reads them depends on the player.
What is the difference between M4V, M4A, and M4B?
Same container, different intents. M4V is video, M4A is audio (typically music), M4B is audiobook (M4A with bookmark chapters). All three descend from MP4. If you have an M4A or M4B, Wave will reject it as audio-only - our scope is video into MP4 with MP3 audio extract as the one bonus path.
iTunes-purchased content downloaded post-2009 - is it protected?
Movies and TV shows purchased from the iTunes Store carry FairPlay DRM regardless of purchase date. iTunes Music dropped DRM in 2009 (that is the iTunes Plus tier). If your source is a movie or show file, expect DRM; if it is a music file, it is almost certainly unprotected.