iMovie/Final Cut Pro X: Red tinted video when using bt601 color matrix

Number:rdar://29926851 Date Originated:09-Jan-2017 03:30 PM
Status:Open Resolved:
Product:iLife Product Version:iMovie 10.1.4 on macOS 10.12.2
Classification:Serious Reproducible:Always
I bought myself a cheap china action cam and discovered that the video looks fine in Quicktime and quicklook. But as soon as I imported the video into iMovie, it was completely red tinted. A short search on youtube brought up that this is a problem known back to 2013.

I digged around a little bit and was able to nail it down to being a problem color matrix codes. My camera records mp4 (don't ask me why, ugh) with a BT.601 color code (although the video can be in HD...). What I discovered is that when I convert this to BT.709 with ffmpeg, the red tint is gone in iMovie.

I consider this to be a serious bug as the scope of this bug is iMovie/Final Cut Pro X and is not easy to discover and workarounds involve retranscoding which is generally not wanted before editing.

Steps to Reproduce:
1. Import the first attached file. It will appear red tinted in iMovie in the preview window on the right side
2. Import the attached file with the suffix "color_matrix_converted" (this file is in BT.709). This file will not be red tinted.

I used ffmpeg (easiest installation with homebrew or macports) with the following command to convert the first file:

ffmpeg -i pathToFile/20170101_000126A.mp4 -vf colormatrix=bt601:bt709 pathToFile/20170101_000126A_colormatrix_corrected.mp4 

Expected Results:
I'd expect iMovie to handle files with bt.601 encoding fine, especially as Quicktime and quicklook already do.

Actual Results:
red tinted video in the case of bt.601 video under special circumstances.

iMovie 10.1.4 on macOS 10.12.2

A workaround suggested on youtube is to use converters that convert the video in some other format.

I poked it with a stick, and the most helpful stick was mediainfo.


'20170101_000126A.mp4' and '20170101_000126A_colormatrix_corrected.mp4' were successfully uploaded.


Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!