Convert QuickTime to MP4
QuickTime is Apple's video format - what QuickTime Player, iMovie, Final Cut, and macOS Screen Recording all save as .mov files. Structurally, QuickTime and MP4 are essentially sibling formats: same file structure, different file extension, and the picture data inside is usually already the same H.264 or HEVC that MP4 uses. So the conversion is nearly always just a wrapper swap - Wave takes seconds regardless of file length and gives you an .mp4, the file type upload forms, website builders and the widest range of devices expect. The exception is ProRes, Apple's editing format, which Windows, web browsers and most phones can't play at all; Wave re-encodes those to H.264. MP4 vs MOV walks through why the two formats are so close yet not quite interchangeable.
What actually changes
Apple's QuickTime File Format shipped in 1991 and became the direct blueprint for the MP4 format standardised ten years later. The two share the same underlying structure - only the identifying label at the start of the file (the four-character "ftyp brand") and the file extension really differ. Compressed video and audio samples stay in place, bit-for-bit. If the "container" concept is unfamiliar, Codecs vs containers covers it in plain English.
On modern content - anything shot on iPhone, recorded through QuickTime Player on macOS, or exported from Final Cut, iMovie, Motion, or Screen Recording via CMD+Shift+5 - the QuickTime .mov almost always contains H.264 or HEVC video with AAC audio. All three codecs are natively MP4-compatible, so Wave rewrites the container header, updates the label, moves the moov atom to the front of the file for fast-start playback, and writes the MP4 out. Nothing is decoded, nothing is re-encoded, and the video and audio streams reach the output identical to the source down to the byte.
The one branch that requires a real transcode is ProRes-in-QuickTime. Apple ProRes 422 and 4444 are on paper MP4-compatible codecs, but no consumer player - not iOS Safari, not Windows Media Foundation, not Chrome, not Android MediaCodec - decodes ProRes-in-MP4 in the wild. Wave detects a ProRes source and re-encodes to H.264 through WebCodecs, so the delivery file plays anywhere any other MP4 plays. For ProRes 4444 with an alpha channel, MP4 has no widely-supported alpha codec, so the alpha composites against black during the re-encode; if alpha preservation matters, keep the source .mov for post workflows and use MP4 only for the delivery layer. See ProRes to MP4 for the deeper technical detail.
Why convert at all, when Windows has played standard .mov files since Windows 7? Three reasons come up most. Some places only take the .mp4 label: upload forms, course platforms, website builders, and a number of TVs and streaming sticks list MP4 but not MOV. Files from editing apps are often ProRes, which only Apple devices and editing software decode - converting turns them into H.264 that plays anywhere and makes them far smaller. And recordings usually carry their index at the end of the file (it can only be written when recording stops), so a web preview has to load the whole file before it plays; Wave moves it to the front. What a wrapper swap can't change is HEVC video, which Windows needs the HEVC Video Extensions to decode, whatever the file is called.
Three steps.
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Step 1
Drop your QuickTime .mov file onto the card, or click Pick a video.
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Step 2
Wave shows you the source details and confirms the fast-copy path (or Re-encode for ProRes sources).
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Step 3
Convert and save the MP4.
Answers, specifically.
Do I need to install QuickTime to convert?
No. Apple discontinued QuickTime for Windows in 2016 and stopped shipping the free player publicly. Wave replaces the need entirely - the conversion runs in your browser, on any OS.
Why does macOS save recordings as .mov instead of .mp4?
macOS defaults to .mov because QuickTime is Apple's native container. Screen Recording (CMD+Shift+5), QuickTime Player's Record Screen and Record Movie, iMovie exports, Final Cut deliveries, and Motion renders all default to .mov. The bytes inside are usually MP4-compatible (H.264 or HEVC + AAC), which is why the container swap works.
Will QuickTime chapter markers survive?
Yes. MP4 chapters use the same chpl / tref atoms as QuickTime chapters, so Wave copies them through. Chapter thumbnails and QuickTime-specific text tracks that some editors write are dropped because MP4 has no equivalent container home for them.
ProRes 4444 alpha channel - does it survive?
No. MP4 has no widely-supported alpha codec that consumer players decode, so the alpha channel composites against black during the re-encode. For alpha preservation, keep the ProRes .mov and use it in workflows that respect alpha (After Effects, Motion, Nuke, Resolve). Deliver the MP4 for playback only.
QuickTime transparent-background videos - can any of them survive?
Only if the transparency was faked with a chroma-keyable green/blue background - keep that as MP4 and composite in the player. Real alpha channels (ProRes 4444, Apple Animation, PNG sequences wrapped in .mov) do not survive because MP4 has nowhere to carry them.
iPhone Live Photo .mov files?
The .mov portion of a Live Photo is a normal short H.264 or HEVC clip and converts like any other QuickTime file - fast copy, no quality loss. The paired .heic still image is a separate file, not part of the .mov, and Wave does not touch it. The MP4 output is just the moving portion.
How long does a QuickTime to MP4 conversion take?
For H.264 or HEVC sources (the fast-copy case), a few seconds regardless of source length - Wave just rewrites the container header. For ProRes sources (the re-encode case), roughly real-time on modern hardware with WebCodecs H.264 acceleration: a 5-minute 1080p ProRes takes about 5 minutes to convert.