QuickTime Movie
Convert MOV files to MP4, WebM, or MKV directly in your browser — no upload, no server. FileDex uses FFmpeg WASM to remux QuickTime containers locally. MOV to MP4 with H.264/AAC is a zero-loss stream copy since both share ISOBMFF ancestry.
Your files never leave your device
Common questions
How do I convert MOV to MP4 without losing quality?
When your MOV contains H.264 video and AAC audio (typical iPhone recordings), FileDex performs a remux — stream copy that transfers data between containers without re-encoding. The output is bit-identical to the source. ProRes MOV files require transcoding to H.264, which is technically lossy but visually transparent at CRF 18.
Why can't Windows play my MOV file?
Windows lacks native ProRes and ALAC codec support. H.264+AAC MOV files play on Windows 10+ via Movies & TV, but ProRes footage requires VLC, DaVinci Resolve, or transcoding to H.264 MP4. Apple deprecated QuickTime for Windows in 2016.
What is the difference between MOV and MP4?
MOV is Apple's QuickTime container; MP4 is the ISO standard derived from it. They share the same atom-based structure and support identical base codecs (H.264, H.265, AAC). MOV adds Apple-specific features like ProRes support and edit lists. For cross-platform delivery, MP4 is preferred. For Apple editing workflows, MOV is required.
Can I convert iPhone MOV recordings to MP4?
Yes. iPhone recordings use H.264 or H.265 + AAC inside MOV containers. FileDex remuxes these to MP4 via stream copy in seconds — no quality loss, no re-encoding. The output plays on every device and platform.
Is ProRes only available in MOV containers?
ProRes was designed for MOV and Final Cut Pro recognizes ProRes only inside MOV containers. While MKV and MXF can technically carry ProRes streams, Apple editing software ignores ProRes in non-MOV containers.
Why does my iPhone MOV video look magenta or washed out on Windows?
Modern iPhones record HEVC in 10-bit HLG HDR by default. Windows players without proper HLG tone mapping misinterpret the transfer function, shifting colors toward magenta or washing them out. To fix this, re-encode the video to SDR H.264 MP4 using a tool that applies tone mapping, or switch your iPhone to Most Compatible mode (under Settings, Camera, Formats) to record in H.264 SDR going forward.
How large are ProRes MOV files compared to H.264?
ProRes files are dramatically larger than H.264. One hour of 1080p24 footage: ProRes 422 HQ runs approximately 100 GB, ProRes 4444 pushes past 200 GB. The same footage in H.264 at CRF 18 is roughly 5-8 GB. ProRes trades file size for instant random access and zero generational loss during editing — every frame decodes independently with no inter-frame prediction.
Can Android phones play MOV files?
Android has limited native MOV support. Stock Android players handle MOV with H.264 and AAC (common iPhone recordings), but ProRes, ALAC, and some HEVC variants may not play. Install VLC for Android for full MOV compatibility, or drop your MOV file into FileDex's converter and select MP4 for universal playback on any Android device.
What makes .MOV special
Apple created the QuickTime container in 1991, and MOV remains the native wrapper for nearly every professional video workflow on macOS and iOS. Internally, a MOV file is built from hierarchical data structures called atoms (also known as boxes in the ISO specification). The top-level atoms mirror what you find in MP4 — ftyp declares the file brand, moov holds all metadata and track descriptions, and mdat stores the raw media bitstream. This is no coincidence. MP4 is a standardized subset of QuickTime's container format; the MPEG-4 Part 12 ISO Base Media File Format (ISOBMFF) was derived directly from Apple's original specification. MOV came first, and MP4 stripped it down for broader interoperability.
Continue reading — full technical deep dive
Atom structure and what MP4 leaves out
The shared ISOBMFF skeleton means most tools that parse MP4 can partially read MOV. The divergence lives in features MP4 never adopted. MOV supports edit lists — instructions that remap, offset, or repeat segments of a track without duplicating media data. A single edit list entry can add an initial delay, trim frames from the start, or loop a section, all without touching mdat. MP4 technically allows edit lists too, but many players ignore them, producing audio sync drift on files that depend on the feature.
Timecode tracks are another MOV-specific strength. These carry SMPTE timecode (HH:MM:SS:FF) embedded as a dedicated track type, giving NLEs frame-accurate references that survive re-wraps, partial exports, and conform workflows. Drop-frame and non-drop-frame variants are both supported. MP4 has no equivalent mechanism; timecode in MP4 workflows typically requires sidecar files or proprietary metadata.
ProRes: why MOV persists in production
The ProRes codec family is the primary reason MOV remains mandatory in professional post-production. ProRes ships in five profiles: 422 Proxy (~45 Mbps for 1080p24), 422 LT (~102 Mbps), 422 (~147 Mbps), 422 HQ (~220 Mbps), and 4444 XQ (~500 Mbps for 1080p24 with alpha). Each doubles the data rate of the tier below it, trading file size for reduced quantization error. ProRes 4444 and 4444 XQ carry full alpha channel transparency — critical for compositing and motion graphics.
A one-hour 1080p24 ProRes 422 HQ file runs approximately 100 GB. ProRes 4444 XQ at the same resolution pushes past 225 GB per hour. These sizes are intentional. ProRes prioritizes decode speed and edit performance over storage efficiency; every frame decodes independently with no inter-frame prediction, so scrubbing and random access are instantaneous.
Apple restricted ProRes encoding to MOV containers. You can remux ProRes into MKV, but most professional tools expect the MOV wrapper and may reject or misinterpret ProRes in other containers. FFmpeg added ProRes encoding support on Linux and Windows, but the output must still target a MOV container for broad NLE compatibility.
iPhone recording and the HDR problem
Modern iPhones shoot video in MOV by default, but the codec inside has changed significantly. iPhone records HEVC in MOV with 10-bit HLG HDR by default since iPhone 12; most Windows and web players silently drop the HDR metadata, shifting colors toward magenta. This happens because HLG (Hybrid Log-Gamma) tone mapping requires explicit support in the decoder and display pipeline. Windows Media Player, many browser-based players, and older versions of VLC either ignore the mdcv and coll atoms carrying the HDR signaling or apply an incorrect transfer function.
The result is footage that looks correct on Apple devices and washed-out or magenta-tinted everywhere else. Converting to SDR with a proper tone-map pass (using tools like FFmpeg's zscale filter or DaVinci Resolve's color management) fixes the color but discards the extended dynamic range. Shooting in "Most Compatible" mode on iPhone forces H.264 in an SDR color space, side-stepping the issue at the cost of larger files and no HDR.
Audio in MOV
MOV supports AAC (lossy, small files), ALAC (Apple's lossless codec), and linear PCM (uncompressed). Professional workflows lean toward PCM-in-MOV because it avoids any decode step during editing and preserves sample-accurate audio without generational loss. A stereo 48 kHz 24-bit PCM track adds roughly 500 MB per hour — negligible next to ProRes video data rates. AAC makes sense for delivery and distribution; PCM makes sense for everything before that.
Limitations
Windows support for MOV has improved but remains inconsistent. Codecs like ProRes require Apple's codec pack or third-party decoders. HEVC in MOV requires the HEVC Video Extensions from the Microsoft Store (paid on some Windows 10 installations, free on Windows 11). Web browsers cannot play MOV files containing ProRes at all; browser HEVC support varies by platform and is absent entirely in Firefox as of early 2026.
File sizes in production workflows are substantial. A feature-length film in ProRes 4444 at 4K can exceed 10 TB. This is manageable on fast NVMe storage but creates real problems for backup, transfer, and archive.
MOV lacks native support for certain codec combinations that MKV handles freely. You cannot put VP9 or AV1 video in a MOV container through any standard mechanism. Subtitle tracks in MOV are limited compared to MKV's support for ASS/SSA and other complex subtitle formats.
When to choose MOV
Use MOV when your workflow is Apple-centric or ProRes-based. Final Cut Pro, DaVinci Resolve, and Premiere Pro all handle MOV natively. If you need timecode tracks, alpha channel video, or edit lists, MOV is the correct container.
Use MP4 for web delivery, streaming, and cross-platform distribution. MP4 with H.264 or H.265 plays on virtually every device and browser.
Use MKV when you need maximum codec flexibility — multiple audio tracks in different formats, complex subtitle support, or open-source codecs like AV1 and Opus. MKV is not supported by Apple's ecosystem without third-party players, which limits its use in mixed-platform professional environments.
.MOV compared to alternatives
| Formats | Criteria | Winner |
|---|---|---|
| .MOV vs .MP4 | Cross-platform playback MP4 plays natively on every OS, browser, and mobile device. MOV requires QuickTime or compatible decoders on Windows/Linux and is primarily an Apple ecosystem format. | MP4 wins |
| .MOV vs .MP4 | Professional editing codec support MOV is the only container that natively supports ProRes 422, ProRes 4444, ProRes RAW, and Apple Intermediate Codec. MP4 does not carry ProRes per ISOBMFF specification. | MOV wins |
| .MOV vs .MKV | ProRes archival ProRes workflows in Final Cut Pro and DaVinci Resolve expect MOV containers. While MKV can technically hold ProRes streams, Apple software does not recognize ProRes inside MKV. | MOV wins |
| .MOV vs .AVI | Metadata and features MOV supports chapters, edit lists, clean aperture atoms, multiple tracks with independent timescales, and rich metadata. AVI is limited to basic interleaved audio/video with no chapter or advanced metadata support. | MOV wins |
Convert .MOV to...
Technical reference
- MIME Type
video/quicktime- Magic Bytes
00 00 00 xx 66 74 79 70ftyp box with qt brand, or starts with moov/mdat atoms.- Developer
- Apple Inc.
- Year Introduced
- 1991
- Open Standard
- No
ftyp box with qt brand, or starts with moov/mdat atoms.
Binary Structure
MOV files use the QuickTime File Format, a hierarchical atom (box) structure that served as the direct ancestor of ISO BMFF. Each atom has a 4-byte big-endian size and 4-byte ASCII type. Modern MOV files begin with an ftyp atom declaring the 'qt ' brand (0x71 74 20 20). Legacy MOV files from the 1990s may start directly with a moov or wide atom without ftyp. The moov atom contains the movie header (mvhd) with timescale and duration, and one or more trak atoms for each media stream. Each trak contains tkhd (track header), mdia (media data: mdhd, hdlr, minf, stbl), and optionally edts (edit list for track timing adjustments). Apple-specific atoms include clef/prof/enof for clean aperture and production aperture dimensions used by Final Cut Pro. The mdat atom holds raw encoded samples, referenced by stco/co64 byte offsets in the sample table (stbl). ProRes codec data inside mdat uses Apple-specific frame headers distinct from standard ISOBMFF codec storage.
| Offset | Length | Field | Example | Description |
|---|---|---|---|---|
0x00 | 4 bytes | ftyp Atom Size | 00 00 00 14 (20 bytes) | Size of the ftyp atom. Legacy MOV files may omit ftyp entirely and start with moov or wide. |
0x04 | 4 bytes | Atom Type | 66 74 79 70 (ftyp) | Identifies this as the file type atom. 'moov' (6D 6F 6F 76) or 'wide' (77 69 64 65) appear here in legacy files. |
0x08 | 4 bytes | Major Brand | 71 74 20 20 (qt ) | QuickTime brand identifier. The two trailing spaces (0x20 0x20) distinguish MOV from MP4 brands like 'isom'. |
0x0C | 4 bytes | Minor Version | 00 00 02 00 | Version of the QuickTime specification. Informational only. |
variable | variable | moov Atom | 6D 6F 6F 76 (moov) | Contains all metadata: movie header (mvhd), track atoms (trak), and user data (udta). Must be present for playback. |
Attack Vectors
- Malformed moov atom with oversized atom length field causes heap overflow in parsers that allocate memory based on declared size before payload validation
- QuickTime edit list (elst) with crafted negative media time values triggers integer underflow in vulnerable QuickTime Player and CoreMedia implementations
- Polyglot MOV/MP4 file with dual-valid ftyp brands bypasses file-type validators that check only the major brand
- Crafted HEVC hvcC configuration box with malicious VPS/SPS/PPS NAL units exploits decoder initialization in CoreMedia framework
Mitigation: FileDex processes MOV files entirely in-browser via FFmpeg WASM inside a Web Worker sandbox. No file data leaves the device. The WASM runtime uses its own codec implementations independent of system QuickTime or CoreMedia frameworks, preventing exploitation of OS-level decoder vulnerabilities.
- Specification QuickTime File Format Specification — Apple Developer Documentation
- Specification ISO/IEC 14496-12:2022 — ISO Base Media File Format (ISOBMFF, derived from QuickTime)
- Registry QuickTime File Format — Library of Congress Format Description (fdd000052)
- Registry video/quicktime — IANA Media Types
- Registry Apple QuickTime Movie (x-fmt/384) — The National Archives PRONOM Registry
- Specification Apple ProRes — SMPTE RDD 36:2015 (ISO-standardized codec for MOV containers)
- History QuickTime File Format — Wikipedia