FFMPEG COMMAND

Convert MOV to MP4 with FFmpeg

A MOV is a container, so the right command depends on what is inside it. Re-encode to H.264 when it holds ProRes or HEVC and you need compatibility; remux without re-encoding when the video is already H.264.

Verified with FFmpeg 9.0.1 on 26 August 2026. Search intent: ffmpeg mov to mp4.

the command

ffmpeg -i input.mov -c:v libx264 -crf 23 -preset medium -pix_fmt yuv420p -c:a aac -b:a 160k -movflags +faststart output.mp4

Re-encodes whatever the MOV contains (ProRes, HEVC, MJPEG, PCM audio) into the most compatible MP4: 8-bit 4:2:0 H.264 video, AAC audio, index at the front. A 119 MB ProRes HQ test file became a 9.2 MB MP4 that plays in every browser.

Flags, explained

-c:v libx264 -crf 23 -preset medium: Re-encode the video to H.264 at the default quality and speed trade-off.
-pix_fmt yuv420p: Force 8-bit 4:2:0 chroma. ProRes is 10-bit 4:2:2; without this flag x264 keeps that format and produces a High 4:2:2 file most players reject.
-c:a aac -b:a 160k: MOV files from cameras often carry uncompressed PCM audio, which MP4 cannot hold. AAC at 160 kbps is the standard replacement.
-movflags +faststart: Puts the index at the start of the MP4 so playback starts before the download completes.
-c copy: Copy the streams unchanged. Only works when the codecs are allowed in MP4 (H.264, HEVC, AAC, MP3 among others).
-tag:v hvc1: The four-character code Apple players expect for HEVC. FFmpeg writes hev1 by default, which QuickTime and Safari ignore.

Variants

Remux without re-encoding when the MOV already holds H.264 and AAC

shell

ffmpeg -i input.mov -c copy -movflags +faststart output.mp4

Copies the streams into an MP4 container in 0.04 s on the test file, with no quality change. Fails with "Could not find tag for codec" when the MOV contains ProRes or PCM audio, because MP4 cannot carry them: re-encode instead.

Keep HEVC from an iPhone but fix the tag

shell

ffmpeg -i input.mov -c copy -tag:v hvc1 -movflags +faststart output.mp4

iPhone footage is HEVC in a MOV. Copying it into an MP4 keeps the quality and size (2.7 MB in, 2.7 MB out); the hvc1 tag is what Safari and QuickTime need to play it.

HEVC to H.264 for players that do not support HEVC

shell

ffmpeg -i input.mov -c:v libx264 -crf 23 -preset medium -pix_fmt yuv420p -c:a aac -b:a 160k -movflags +faststart output.mp4

Same as the primary command, shown for the HEVC case: the 720p HEVC test file became a 3.7 MB H.264 MP4 that older Android devices, Windows without the HEVC extension and most web players accept.

Pitfalls we hit

Forgetting -pix_fmt yuv420p with a ProRes source produced a High 4:2:2 10-bit H.264 file (yuv422p10le, 12.8 MB) that browsers and phones will not play. With the flag: yuv420p, 9.2 MB.
-c copy fails on ProRes MOVs: "Could not find tag for codec prores in stream #0, codec not currently supported in container". It also fails on PCM audio. Re-encode those streams.
HEVC copied without -tag:v hvc1 plays in VLC and Chrome but not in Safari or QuickTime.
MOV and MP4 are both MPEG-4 Part 12 containers. Renaming the file changes nothing; the codecs inside decide what plays.

How we verified it

Run with FFmpeg 9.0.1 on 26 August 2026. ProRes HQ MOV (1920x1080, yuv422p10le, PCM, 119,259,914 bytes) → primary command: H.264 High yuv420p, AAC, 9,166,214 bytes; without -pix_fmt: High 4:2:2 yuv422p10le, 12,791,420 bytes. H.264 MOV → -c copy: 0.04 s, 4,808,662 bytes, streams unchanged. HEVC MOV (2,689,537 bytes) → -c copy -tag:v hvc1: 2,689,482 bytes, hvc1; → libx264: 3,682,905 bytes. ProRes MOV with -c copy failed as described.

The same edit as a typed operation

convert_video_to_mp4 probes the source first and picks stream copy when the codecs already fit MP4, or an H.264 yuv420p plus AAC re-encode with faststart when they do not. The 4:2:2 and PCM traps are handled without any option.

MCP tool: convert_video_to_mp4POST /api/v1/tools/video-to-mp4

request body

{
  "inputs": [{ "id": "main", "url": "https://example.com/video.mov" }],
  "options": {}
}

Run video to mp4 in the browser Connect MCP API docs

FAQ

Why is my MP4 huge after converting from MOV?

Either the MOV held an already compressed H.264 stream that you re-encoded at a low CRF, or you kept a 10-bit 4:2:2 pixel format. Remux with -c copy when the codec fits, or add -pix_fmt yuv420p and a CRF of 23 or higher.

Does converting MOV to MP4 lose quality?

Not with -c copy, which keeps the exact same streams. A re-encode from ProRes or HEVC to H.264 loses a little, kept invisible at CRF 18 to 23.

Why does the MP4 not play on my iPhone or in Safari?

Usually one of two things: HEVC without the hvc1 tag, or 10-bit 4:2:2 H.264 from a ProRes source. The primary command and the hvc1 variant above avoid both.

What is the fastest way to convert MOV to MP4?

Remuxing with -c copy: it rewrites the container without touching the video, in a fraction of a second. It only works when the MOV already contains MP4-compatible codecs such as H.264, HEVC and AAC.

Related commands

All FFmpeg commands